Yocto-rs485 : user's guide

Yocto-RS485 : User's guide

1. Introduction

The Yocto-RS485 is a USB 56x20mm module with a serial port at the RS485 standard (transmission in differential mode, enabling communications at more than a 1000m). It natively supports several serial protocols, including MODBUS. The module has a buffer memory enabling it to communicate asynchronously, if need be. The Yocto-RS485 can also work as an RS485 communication analyzer. In the opposite to most USB/serial adapters, it requires neither a driver and nor a virtual COM port.

On top of offering low level serial communications, the Yocto-RS485 can autonomously question and analyze the RS485 output of any appliance to then present the results in the manner of a Yoctopuce sensor. In other words, the Yocto-RS485 can transform any sensor equipped with an RS485 output into the software equivalent of a Yoctopuce sensor, data logger included.

An important characteristic of the Yocto-RS485 is to be an insulated module: the RS485 part of the module is electrically insulated from the USB part. Therefore, you can connect the module to devices powered by the mains, for example, without risking to destroy your computer, even if the appliance is not on the same phase.

Beware, the Yocto-RS485 is not a classic RS485 to USB adaptor: it does not create a virtual COM port, you cannot therefore use it with an application designed to use a COM port.

The Yocto-RS485 module

The Yocto-RS485 is not in itself a complete product. It is a component intended to be integrated into a solution used in laboratory equipments, or in industrial process-control equipments, or for similar applications in domestic and commercial environments. In order to use it, you must at least install it in a protective enclosure and connect it to a host computer.

Yoctopuce thanks you for buying this Yocto-RS485 and sincerely hopes that you will be satisfied with it. The Yoctopuce engineers have put a large amount of effort to ensure that your Yocto-RS485 is easy to install anywhere and easy to drive from a maximum of programming languages. If you are nevertheless disappointed with this module, or if you need additional information, do not hesitate to contact Yoctopuce support:

E-mail address:	support@yoctopuce.com
Web site:	www.yoctopuce.com
Postal address:	Chemin des Journaliers, 1
ZIP code, city:	1236 Cartigny
Country:	Switzerland

1.1. Safety Information

The Yocto-RS485 is designed to meet the requirements of IEC 61010-1:2010 safety standard. It does not create any serious hazards to the operator and surrounding area, even in single fault condition, as long as it is integrated and used according to the instructions contained in this documentation, and in this section in particular.

Protective enclosure

The Yocto-RS485 should not be used without a protective enclosure, because of the accessible bare electronic components. For optimal safety, it should be put into a non-metallic, non-inflammable enclosure, resistant to a mechanical stress level of 5 J. For instance, use a polycarbonate (e.g. LEXAN) enclosure rated IK08 with a IEC 60695-11-10 flammability rating of V-1 or better. Using a lower quality enclosure may require specific warnings for the operator and/or compromise conformity with the safety standard.

Maintenance

If a damage is observed on the electronic board or on the enclosure, it should be replaced in order to ensure continued safety of the equipment, and to prevent damaging other parts of the system due to overload that a short circuit could cause.

Identification

In order to ease the maintenance and the identification of risks during maintenance, you should affixate the water-resistant identification label provided together with the electronic board as close as possible to the device. If the device is put in a dedicated enclosure, the identification label should be affixated on the outside of the enclosure. This label is resistant to humidity, and can hand rubbing with a piece of cloth soaked with water.

Identification label is integrated in the package label.

Application

The safety standard applied is intended to cover laboratory equipment, industrial process-control equipment and similar applications in residential or commercial environment. If you intend to use the Yocto-RS485 for another kind of application, you should check the safety regulations according to the standard applicable to your application.

In particular, the Yocto-RS485 is not certified for use in medical environments or for life-support applications.

Environment

The Yocto-RS485 is not certified for use in hazardous locations, explosive environments, or life-threatening applications. Environmental ratings are provided below.

IEC 61140 Protection Class III

The Yocto-RS485 has been designed to work with safety extra-low voltages only. Do not exceed voltages indicated in this manual, and never connect to the Yocto-RS485 terminal blocks any wire that could be connected to the mains.

1.2. Environmental conditions

Yoctopuce devices have been designed for indoor use in a standard office or laboratory environment (IEC 60664 pollution degree 2): air pollution is expected to be limited and mainly non-conductive. Relative humidity is expected to be between 10% and 90% RH, non condensing. Use in environments with significant solid pollution or conductive pollution requires a protection from such pollution using an IP67 or IP68 enclosure. The products are designed for use up to altitude 2000m.

All Yoctopuce devices are warranted to perform according to their documentation and technical specifications under normal temperature conditions according to IEC61010-1, i.e. 5°C to 40°C. In addition, most devices can also be used on an extended temperature range, where some limitations may apply from case to case.

The extended operating temperature range for the Yocto-RS485 is -30...85°C. This temperature range has been determined based on components manufacturer recommendations, and on controlled environment tests performed during a limited duration (1h). If you plan to use the Yocto-RS485 in harsh environments for a long period of time, we strongly advise you to run extensive tests before going to production.

2. Presentation

1:	Micro-B USB socket	5:	DATA +
2:	Yocto-led	6:	DATA -
3:	Yocto-button	7:	Ground
4:	Activity leds	8:	Termination switch

2.1. Common elements

All Yocto-modules share a number of common functionalities.

USB connector

Yoctopuce modules all come with a USB 2.0 micro-B socket. Warning: the USB connector is simply soldered in surface and can be pulled out if the USB plug acts as a lever. In this case, if the tracks stayed in position, the connector can be soldered back with a good iron and using flux to avoid bridges. Alternatively, you can solder a USB cable directly in the 1.27mm-spaced holes near the connector.

If you plan to use a power source other then a standard USB host port to power the device through the USB connector, that power source must respect the assigned values of USB 2.0 specifications:

Voltage min.: 4.75 V DC
Voltage max.: 5.25 V DC
Over-current protection: 5.0 A max.

A higher voltage is likely to destroy the device. THe behaviour with a lower voltage is not specified, but it can result firmware corruption.

Yocto-button

The Yocto-button has two functionalities. First, it can activate the Yocto-beacon mode (see below under Yocto-led). Second, if you plug in a Yocto-module while keeping this button pressed, you can then reprogram its firmware with a new version. Note that there is a simpler UI-based method to update the firmware, but this one works even in case of severely damaged firmware.

Yocto-led

Normally, the Yocto-led is used to indicate that the module is working smoothly. The Yocto-led then emits a low blue light which varies slowly, mimicking breathing. The Yocto-led stops breathing when the module is not communicating any more, as for instance when powered by a USB hub which is disconnected from any active computer.

When you press the Yocto-button, the Yocto-led switches to Yocto-beacon mode. It starts flashing faster with a stronger light, in order to facilitate the localization of a module when you have several identical ones. It is indeed possible to trigger off the Yocto-beacon by software, as it is possible to detect by software that a Yocto-beacon is on.

The Yocto-led has a third functionality, which is less pleasant: when the internal software which controls the module encounters a fatal error, the Yocto-led starts emitting an SOS in morse ¹. If this happens, unplug and re-plug the module. If it happens again, check that the module contains the latest version of the firmware, and, if it is the case, contact Yoctopuce support².

Current sensor

Each Yocto-module is able to measure its own current consumption on the USB bus. Current supply on a USB bus being quite critical, this functionality can be of great help. You can only view the current consumption of a module by software.

Serial number

Each Yocto-module has a unique serial number assigned to it at the factory. For Yocto-RS485 modules, this number starts with RS485MK1. The module can be software driven using this serial number. The serial number cannot be modified.

Logical name

The logical name is similar to the serial number: it is a supposedly unique character string which allows you to reference your module by software. However, in the opposite of the serial number, the logical name can be modified at will. The benefit is to enable you to build several copies of the same project without needing to modify the driving software. You only need to program the same logical name in each copy. Warning: the behavior of a project becomes unpredictable when it contains several modules with the same logical name and when the driving software tries to access one of these modules through its logical name. When leaving the factory, modules do not have an assigned logical name. It is yours to define.

2.2. Specific elements

The connector

The RS485 input/output port of the Yocto-RS485 module is a terminal with DATA+, DATA-, and ground contacts. Cabling of an RS485 usually has these three wires, to which devices are cabled in parallel. Sometimes ground is left out from the bus, but this is a design weakness which works only when all the devices have a relatively similar ground. The EIA/TIA standard requires a ground wire.

The communication circuit is a safety extra low voltage (SELV) circuit. It should not be presented with voltages exceeding 20V, nor connected to mains circuits. The Yocto-RS485 endurance to surge and lightning transiants has not been tested. If you intend to use the Yocto-RS485 with wires longer than 30m or running outside, you should perform this testing yourself (see IEC 61000-4-5).

Activity leds

The Yocto-RS485 has two green leds reflecting the RS485 port activity, the first one for receiving and the second for transmitting.

The termination switch

To optimize transmission quality on a RS485 bus, it is recommended to terminate it at both ends with a resistance of 120Ω between D+ and D-. To avoid using an external component, the Yocto-RS485 is equipped with an embedded resistance that you can connect to the bus by simply setting its micro-switch to ON.

2.3. Functional insulation

The Yocto-RS485 is designed as two distinct electrical circuits, separated by a functional insulation. This insulation plays no role for the operator safety, since both circuits of the Yocto-RS485 work with safety extra low voltages (SELV) and are accessible without risk at any time. The insulation has been added in excess of safety requirements, to improve the reliability and the ease of use of the Yocto-RS485, allowing both circuits to work with different reference grounds.

Although the insulation plays no role for security, it has been designed according to the rules that would apply for a supplementary insulation on a secondary circuit. Its specifications of the functional insulation are as follows³:

Insulation voltage⁴: 2.5kV
Clearance distance: 4.5mm
Creepage distance: 4.5mm
Material group: Cat IIIa (FR4)

2.4. Optional accessories

The accessories below are not necessary to use the Yocto-RS485 module but might be useful depending on your project. These are mostly common products that you can buy from your favorite hacking store. To save you the tedious job of looking for them, most of them are also available on the Yoctopuce shop.

Screws and spacers

In order to mount the Yocto-RS485 module, you can put small screws in the 2.5mm assembly holes, with a screw head no larger than 4.5mm. The best way is to use threaded spacers, which you can then mount wherever you want. You can find more details on this topic in the chapter about assembly and connections.

Micro-USB hub

If you intend to put several Yoctopuce modules in a very small space, you can connect them directly to a micro-USB hub. Yoctopuce builds a USB hub particularly small for this purpose (down to 20mmx36mm), on which you can directly solder a USB cable instead of using a USB plug. For more details, see the micro-USB hub information sheet.

YoctoHub-Ethernet, YoctoHub-Wireless and YoctoHub-GSM

You can add network connectivity to your Yocto-RS485, thanks to the YoctoHub-Ethernet, the YoctoHub-Wireless and the YoctoHub-GSM which provides repectiveley Ethernet, WiFi and GSM connectivity. All of them can drive up to three devices and behave exactly like a regular computer running a VirtualHub.

1.27mm (or 1.25mm) connectors

In case you wish to connect your Yocto-RS485 to a Micro-hub USB or a YoctoHub without using a bulky USB connector, you can use the four 1.27mm pads just behind the USB connector. There are two options.

You can mount the Yocto-RS485 directly on the hub using screw and spacers, and connect it using 1.27mm board-to-board connectors. To prevent shortcuts, it is best to solder the female connector on the hub and the male connector on the Yocto-RS485.

You can also use a small 4-wires cable with a 1.27mm connector. 1.25mm works as well, it does not make a difference for 4 pins. This makes it possible to move the device a few inches away. Don't put it too far away if you use that type of cable, because as the cable is not shielded, it may cause undesirable electromagnetic emissions.

Enclosure

Your Yocto-RS485 has been designed to be installed as is in your project. Nevertheless, Yoctopuce sells enclosures specifically designed for Yoctopuce devices. These enclosures have removable mounting brackets and magnets allowing them to stick on ferromagnetic surfaces. More details are available on the Yoctopuce web site ⁵. The suggested enclosure model for your Yocto-RS485 is the YoctoBox-Long-Thick-Black.

You can install your Yocto-RS485 in an optional enclosure

3. First steps

By design, all Yoctopuce modules are driven the same way. Therefore, user's guides for all the modules of the range are very similar. If you have already carefully read through the user's guide of another Yoctopuce module, you can jump directly to the description of the module functions.

3.1. Prerequisites

In order to use your Yocto-RS485 module, you should have the following items at hand.

A computer

Yoctopuce modules are intended to be driven by a computer (or possibly an embedded microprocessor). You will write the control software yourself, according to your needs, using the information provided in this manual.

Yoctopuce provides software libraries to drive its modules for the following operating systems: Windows, macOS X, Linux, and Android. Yoctopuce modules do not require installing any specific system driver, as they leverage the standard HID driver⁶ provided with every operating system.

Windows versions currently supported are: Windows XP, Windows 2003, Windows Vista, Windows 7, Windows 8 and Windows 10. Both 32 bit and 64 bit versions are supported. The programming library is also available for the Universal Windows Platform (UWP), which is supported by all flavors of Windows 10, including Windows 10 IoT. Yoctopuce is frequently testing its modules on Windows 7 and Windows 10.

MacOS versions currently supported are: Mac OS X 10.9 (Maverick), 10.10 (Yosemite), 10.11 (El Capitan), macOS 10.12 (Sierra), macOS 10.13 (High Sierra) and macOS 10.14 (Mojave). Yoctopuce is frequently testing its modules on macOS 10.14.

Linux kernels currently supported are the 2.6 branch, the 3.x branch and the 4.x branch. Other versions of the Linux kernel, and even other UNIX variants, are very likely to work as well, as Linux support is implemented through the standard libusb API. Yoctopuce is frequently testing its modules on Linux kernel 4.15 (Ubuntu 18.04 LTS).

Android versions currently supported are: Android 3.1 and later. Moreover, it is necessary for the tablet or phone to support the Host USB mode. Yoctopuce is frequently testing its modules on Android 7.x on a Samsung Galaxy A6 with the Java for Android library.

A USB 2.0 cable, type A-micro B

USB 2.0 connectors exist in three sizes: the "standard" size that you probably use to connect your printer, the very common mini size to connect small devices, and finally the micro size often used to connect mobile phones, as long as they do not exhibit an apple logo. All USB modules manufactured by Yoctopuce use micro size connectors.

The most common USB 2.0 connectors: A, B, Mini B, Micro A, Micro B⁷

To connect your Yocto-RS485 module to a computer, you need a USB 2.0 cable of type A-micro B. The price of this cable may vary a lot depending on the source, look for it under the name USB 2.0 A to micro B Data cable. Make sure not to buy a simple USB charging cable without data connectivity. The correct type of cable is available on the Yoctopuce shop.

You must plug in your Yocto-RS485 module with a USB 2.0 cable of type A - micro B

If you insert a USB hub between the computer and the Yocto-RS485 module, make sure to take into account the USB current limits. If you do not, be prepared to face unstable behaviors and unpredictable failures. You can find more details on this topic in the chapter about assembly and connections.

3.2. Testing USB connectivity

At this point, your Yocto-RS485 should be connected to your computer, which should have recognized it. It is time to make it work.

Go to the Yoctopuce web site and download the Virtual Hub software⁸. It is available for Windows, Linux, and Mac OS X. Normally, the Virtual Hub software serves as an abstraction layer for languages which cannot access the hardware layers of your computer. However, it also offers a succinct interface to configure your modules and to test their basic functions. You access this interface with a simple web browser⁹. Start the Virtual Hub software in a command line, open your preferred web browser and enter the URL http://127.0.0.1:4444. The list of the Yoctopuce modules connected to your computer is displayed.

Module list as displayed in your web bowser

3.3. Localization

You can then physically localize each of the displayed modules by clicking on the beacon button. This puts the Yocto-led of the corresponding module in Yocto-beacon mode. It starts flashing, which allows you to easily localize it. The second effect is to display a little blue circle on the screen. You obtain the same behavior when pressing the Yocto-button of the module.

3.4. Test of the module

The first item to check is that your module is working well: click on the serial number corresponding to your module. This displays a window summarizing the properties of your Yocto-RS485.

Properties of the Yocto-RS485 module

This window allows you, among other things, to play with your module to check how it is working. You can find there a simplified terminal emulator enabling you to test the communications with your device.

As soon as the window opens, the last 4KB of messages found in the device memory are displayed. As long as messages are exchanged, they will be appended to the list. By typing a keyword next to the magnifier icon, you can restrict the display to messages including the selected keyword. If needed, you can temporarily pause the display update using button pause. The user interface can handle hundredths of messages. After a few thousands, the Web browser is likely to start slowing down, but you can always use the clear button to empty the display history and the device memory.

Each message is prepended by a timestamp, relative to the first message, and by the direction of the transmission - send or receive. To make it easier to read, one of the direction is highlighted as well. The message timestamps are recorded directly by the device, at the exact time when the message is detected. They are therefore quite precise, with a resolution of a millisecond.

Regardless of the selected protocol type, you can switch the display between ASCII and hex mode using the button view hex / view ASCII. Be aware however that when the capture is made using a text-based protocol (Line-based ASCII protocol, STX/ETX-based ASCII protocol or generic ASCII stream), all non-textual control codes will be automatically filtered and will therefore not appear, even in hex mode. So use a binary mode protocol if you need to check the control codes.

If you need to study or to compare a communication involving many messages, use the button export to open the whole set of messages in a larger window. The exported view includes simultaneously hex codes, with 16 bytes per line, and the corresponding ASCII characters, formatted as text lines to facilitate reading. This view can be saved into a stand-alone HTML file if needed, using the Save button, to be reopened later using any Web browser.

3.5. Configuration

When, in the module list, you click on the configure button corresponding to your module, the configuration window is displayed.

Yocto-RS485 module configuration.

Firmware

The module firmware can easily be updated with the help of the interface. Firmware destined for Yoctopuce modules are available as .byn files and can be downloaded from the Yoctopuce web site.

To update a firmware, simply click on the upgrade button on the configuration window and follow the instructions. If the update fails for one reason or another, unplug and re-plug the module and start the update process again. This solves the issue in most cases. If the module was unplugged while it was being reprogrammed, it does probably not work anymore and is not listed in the interface. However, it is always possible to reprogram the module correctly by using the Virtual Hub software ¹⁰ in command line ¹¹.

Logical name of the module

The logical name is a name that you choose, which allows you to access your module, in the same way a file name allows you to access its content. A logical name has a maximum length of 19 characters. Authorized characters are A..Z, a..z, 0..9, _, and -. If you assign the same logical name to two modules connected to the same computer and you try to access one of them through this logical name, behavior is undetermined: you have no way of knowing which of the two modules answers.

Luminosity

This parameter allows you to act on the maximal intensity of the leds of the module. This enables you, if necessary, to make it a little more discreet, while limiting its power consumption. Note that this parameter acts on all the signposting leds of the module, including the Yocto-led. If you connect a module and no led turns on, it may mean that its luminosity was set to zero.

Logical names of functions

Each Yoctopuce module has a serial number and a logical name. In the same way, each function on each Yoctopuce module has a hardware name and a logical name, the latter can be freely chosen by the user. Using logical names for functions provides a greater flexibility when programming modules.

Serial port configuration

You can configure the workings of the serial port in this window. You can select the speed, the encoding, the parity, the number of stop bits, and so on.

You can also select the protocol you want to use on the serial line. You can find more details about these different protocols in the chapter entitled 5. The serial port.

4. Assembly and connections

This chapter provides important information regarding the use of the Yocto-RS485 module in real-world situations. Make sure to read it carefully before going too far into your project if you want to avoid pitfalls.

4.1. Fixing

While developing your project, you can simply let the module hang at the end of its cable. Check only that it does not come in contact with any conducting material (such as your tools). When your project is almost at an end, you need to find a way for your modules to stop moving around.

Examples of assembly on supports

The Yocto-RS485 module contains 2.5mm assembly holes. You can use these holes for screws. The screw head diameter must not be larger than 4.5mm or they will damage the module circuits. Make sure that the lower surface of the module is not in contact with the support. We recommend using spacers, but other methods are possible. Nothing prevents you from fixing the module with a glue gun; it will not be good-looking, but it will hold.

If your intend to screw your module directly against a conducting part, for example a metallic frame, insert an isolating layer in between. Otherwise you are bound to induce a short circuit: there are naked pads under your module. Simple insulating tape should be enough.

4.2. Connections

The RS485 standard consists in driving the DATA+ and DATA- lines in differential mode, enabling it to route the signal on very long distances, sometimes more than a 1000 meters. the Yocto-RS485 communicates in half-duplex: each device speaks one after the other on the same line. RS485 wiring usually has three wires: DATA+, DATA-, and ground. Sometimes ground is missing from the bus but this is a design weakness which works only when all the devices have a rather similar ground. The EIS/TIA-485 standard requires a ground wire.

The Yocto-RS485 is an insulated module: do not artificially connect the RS485 bus ground to the USB bus ground, you would lose the the benefits from the insulation protecting your computer.

Direct connection to an RS485 device

The termination

In the opposite to a classic serial communication which works only from point to point, RS485 devices can be organized in a bus. Each end of the bus must end with a 120Ω resistance. To avoid using an external component, such a termination resistance is embedded into the Yocto-RS485. You can optionally enable it with a micro-switch located right next to the terminal.

Organization as a bus: beware of the termination.

4.3. USB power distribution

Although USB means Universal Serial BUS, USB devices are not physically organized as a flat bus but as a tree, using point-to-point connections. This has consequences on power distribution: to make it simple, every USB port must supply power to all devices directly or indirectly connected to it. And USB puts some limits.

In theory, a USB port provides 100mA, and may provide up to 500mA if available and requested by the device. In the case of a hub without external power supply, 100mA are available for the hub itself, and the hub should distribute no more than 100mA to each of its ports. This is it, and this is not much. In particular, it means that in theory, it is not possible to connect USB devices through two cascaded hubs without external power supply. In order to cascade hubs, it is necessary to use self-powered USB hubs, that provide a full 500mA to each subport.

In practice, USB would not have been as successful if it was really so picky about power distribution. As it happens, most USB hub manufacturers have been doing savings by not implementing current limitation on ports: they simply connect the computer power supply to every port, and declare themselves as self-powered hub even when they are taking all their power from the USB bus (in order to prevent any power consumption check in the operating system). This looks a bit dirty, but given the fact that computer USB ports are usually well protected by a hardware current limitation around 2000mA, it actually works in every day life, and seldom makes hardware damage.

What you should remember: if you connect Yoctopuce modules through one, or more, USB hub without external power supply, you have no safe-guard and you depend entirely on your computer manufacturer attention to provide as much current as possible on the USB ports, and to detect overloads before they lead to problems or to hardware damages. When modules are not provided enough current, they may work erratically and create unpredictable bugs. If you want to prevent any risk, do not cascade hubs without external power supply, and do not connect peripherals requiring more than 100mA behind a bus-powered hub.

In order to help you controlling and planning overall power consumption for your project, all Yoctopuce modules include a built-in current sensor that indicates (with 5mA precision) the consumption of the module on the USB bus.

Note also that the USB cable itself may also cause power supply issues, in particular when the wires are too thin or when the cable is too long ¹². Good cables are usually made using AWG 26 or AWG 28 wires for data lines and AWG 24 wires for power.

4.4. Electromagnetic compatibility (EMI)

Connection methods to integrate the Yocto-RS485 obviously have an impact on the system overall electromagnetic emissions, and therefore also impact the conformity with international standards.

When we perform reference measurements to validate the conformity of our products with IEC CISPR 11, we do not use any enclosure but connect the devices using a shielded USB cable, compliant with USB 2.0 specifications: the cable shield is connected to both connector shells, and the total resistance from shell to shell is under 0.6Ω. The USB cable length is 3m, in order to expose one meter horizontally, one meter vertically and keep the last meter close to the host computer within a ferrite bead.

If you use a non-shielded USB cable, or an improperly shielded cable, your system will work perfectly well but you may not remain in conformity with the emission standard. If you are building a system made of multiple devices connected using 1.27mm pitch connectors, or with a sensor moved away from the device CPU, you can generally recover the conformity by using a metallic enclosure acting as an external shield.

Still on the topic of electromagnetic compatibility, the maximum supported length of the USB cable is 3m. In addition to the voltage drop issue mentionned above, using longer wires would require to run extra tests to assert compatibility with the electromagnetic immunity standards.

5. The serial port

In the opposite to classic RS232 adapters, the Yocto-RS485 serial port is not a simple gateway to a virtual COM port. It is based on an active communication management by the module and offers a full programming interface like for all Yoctopuce modules. In particular,

it does not require a driver
its identifier remains the same when one changes the USB port on which it is connected
it does not install any virtual COM port
it can recognize some common message formats to ease software access
it has circular input and output buffers, both of a size of 16 KB
it permanently stores the data it receives, even when the computer is rebooting
it can be accessed in parallel by several applications (data read by one application remain available for another application)
it can measure the precise delay between each received byte to correctly decode binary protocols such as MODBUS

Thanks to these functions, you can use the Yocto-RS485 to, for example, perform serial communications from a simple command line or from HTTP request on a REST interface, without risking to lose messages.

The Yocto-RS485 RS485 port follows ANSI/TIA/EIA-485-A-98 and ISO 8482:1987(E) standards, and provides a ±15 kV ESD protection on RS-485 input/output pins.

5.1. Configurable parameters

The Yocto-RS485 serial port can generate communication speeds from 110 bits/s to 250'000 Kbits/s. You can configure it to use 7 or 8 bits of data, with or without parity (even or odd), with 1 or 2 stop bits.¹³

You can also configure in the module the protocol family to be used on the serial port. This allows the module to make a pre-analysis of the data directly when it receives them and to optimize the information exchange with the application code, in particular to signal the reception of new data at the most appropriate time (that is when a full message is received). Details of supported protocol families are available in the following sections.

5.2. Text-line based protocol

Called Line-based ASCII protocol in the configuration interface, it is a very common family for measuring tools. The host machine sends its configuration commands in the shape of commands ending by a line feed. The measuring tool sends its measures and its receipts as lines of text as well. Among the machines using this kind of protocol, you can find:

GSM or other communication modules (AT commands)
navigation tools following the NMEA standard (including GPS)
Dylos particle sensors
Geiger counters from Mazur Instruments
and so on.

The most useful API functions in this working mode are:

reset(), to empty the incoming buffer
get_lastMessage() to obtain the latest line (latest measure) transmitted
queryMessage() to send a command and wait for an answer for a given time set in advance.
writeLine() and readLine(), to send commands and read answers manually, line by line (non-blocking functions)

In line mode, if you register a value notification callback, it is called after each newly received message.

5.3. Text protocol delimited by STX and ETX

Called STX/ETX-based ASCII protocol in the configuration interface, it is specific encoding used by some measuring tools. Message are sent in clear text, framed by a STX code at the beginning and an ETX code at the end. Proprietary binary codes may follow after the ETX code, but they will be ignored by the interface to make the decoding easier.

The most useful API functions in this working mode are:

reset(), to empty the incoming buffer
writeStxEtx(), to send a command manually, including the STX and ETX markers
get_lastMessage() to obtain the latest line (latest measure) transmitted
queryMessage() to send a command and wait for an answer for a given time set in advance.

In line mode, if you register a value notification callback, it is called after each newly received message.

5.4. Frame-based binary protocol

CalledFrame-based binary protocol in the configuration interface, this family includes all proprietary protocols based on exchanging binary messages (non-textual).The MODBUS RTU protocol is a particular case which is explicitly managed (see below). But any other variant of binary frame exchanges can be used here. The Yocto-RS485 is able to separate the distinct received messages thanks to a measure of the delay in the successive byte reception. When you select a protocol based on binary frames, you can specify the space delimiting the separation between two frames.

Note that binary frames are limited to 256 bytes. Above this limit, a new frame is created for the later part of the message. The timestamp of the frames make it possible to recognize that the next frame is the continuation of the previous one.

If your binary protocol does not specify any constraint on the space between frames and space between the characters of a frame, you had better use the "Binary data stream" family below.

The most useful API functions in this working mode are:

reset(), to empty the incoming buffer
get_lastMessage() to obtain the hexadecimal representation of the latest frame received
writeHex() to send a frame, given in hexadecimal
readMessages() to look for a frame corresponding to a given regular expression
readHex() to read a given number of bytes in hexadecimal (independently of frame distinctions)
queryHex() to send an hexadecimal command and wait for an answer for a given time set in advance.

In binary frame mode, if you register a value notification callback, it is called for each newly received frame.

5.5. MODBUS protocol

The MODBUS protocol is much used in the industry and for monitoring the technical infrastructure of buildings. The protocol has two variants: the MODBUS ASCII mode where messages are exchanged as lines of hexadecimal code, and the MODBUS RTU mode where messages are exchanged directly as binary frames. To dialog with a MODBUS device, you imperatively must use the same mode as configured in the device. In theory, all the devices conforming to the standard must support the MODBUS RTU mode.

MODBUS messages correspond to relatively simple operations to read and write in binary registers (called bits or coils) and to 16 bit words. The host systematically initiates the exchange, to which the "slave" answers. The Yocto-RS485 transparently manages the ASCII and RTU modes and computes by itself the validation bytes (LRC and CRC) specified in the MODBUS protocol. The most useful API functions in MODBUS mode are:

modbusReadBits() to read one or several status bits ("Read coils" MODBUS function)
modbusReadInputBits() to read one or several input bits ("Read input bits" MODBUS function)
modbusReadRegisters() to read one or several status/holding registers ("Read holding registers" MODBUS function)
modbusReadInputRegisters() to read one or several input registers ("Read input registers" MODBUS function)
modbusWriteBit() to modify a status/holding bit ("Write single coil" MODBUS function)
modbusWriteBits() to modify several status/holding bits ("Write multiple coils" MODBUS function)
modbusWriteRegister() to modify a single status/holding register ("Write single registers" MODBUS function)
modbusWriteRegisters() to modify several status/holding registers ("Write multiple registers" MODBUS function)
modbusWriteAndReadRegisters() to modify several registers and then directly read several status/holding registers ("Read/Write Multiple Registers" MODBUS function)
queryMODBUS() to send an arbitrary MODBUS request and wait for the answer

In MODBUS mode, if you register a value notification callback, it is called each time an answer is received.

5.6. Wiegand Protocol

The Wiegand protocol is mainly used in access control systems (magnetic cards, RFID readers). There are many Wiegand variants, but all of them end up in sending a sequence of bits to identify an access tag. The Yocto-RS485 can decode Wiegand messages in two ways: either by sending the bit sequence "as is", in ASCII, as a string of zero and ones, or by combining the bits into bytes in order to facilitate the decoding. In order to allow the bits to be properly combined into bytes, the only thing you have to specify is the number of parity bits that needs to be taken out at the head of the message.

The most useful API functions in Wiegand mode are:

reset(), to empty the incoming buffer
get_lastMessage(), to read the ID of the last access tag seen
reset() to forget all access tag IDs previously seen

5.7. ASCII data stream

Called Generic ASCII stream in the configuration interface, it is the most primitive text communication variant, similar to a file access. As the Yocto-RS485 has a 16KB read buffer, it is even possible to move the read position pointer freely within this window. Note that the read position pointer is specific to each application: if two applications read access the serial port through the network simultaneously, moving the read position pointer of one application does not have any impact on data availability for the other application.

The most useful API functions to to work with an ASCII data stream are:

reset(), to empty the incoming buffer
writeStr() to send a character string
readStr() to read a character string
read_seek() to move the read position pointer in the buffer
get_rxCount() to know the position of the end of the receiving buffer

In stream mode, if you register a value notification callback, it is called each time a byte is received.

5.8. Binary data stream

Called Generic byte stream in the configuration interface, it is the binary equivalent of the ASCII data stream. You access it as you would a binary file, with the possibility to move the read position pointer freely inside the 16KB read buffer. Note that the read position pointer is specific to each application: if two applications read access the serial port through the network simultaneously, moving the read position pointer of one application does not have any impact on data availability for the other application.

The most useful API functions to to work with a binary data stream are:

reset(), to empty the incoming buffer
writeHex() to send a byte string (given a hexadecimal string)
readHex() to read a byte string (given as a hexadecimal string)
read_seek() to move the read position pointer within the buffer
get_rxCount() to know the position of the end of the receiving buffer

In stream mode, if you register a value notification callback, it is called each time a byte is received.

5.9. Serial communication analyzer

You can use the Yocto-RS485 as a serial protocol analyzer by connecting it on the cable that directly connects two devices communicating via a serial protocol. In this specific mode, the Yocto-RS485 transmitting signals are not wired (ensuring trouble-free operations), and the TD and RD lines to be monitored are two receiving signals on the Yocto-RS485. It is then able to read the traffic going through both ways on the serial cable, identifying the direction of the communication.

Wiring to use the Yocto-RS485 in analyzer mode

If you want, you can buy a ready-to-use adapter on Yoctopuce shop with a female DB9 socket and a male DB9 plug. You will find it under the name RS232-Snooping-Adapter¹⁴.

6. Automatic measures

On top of offering the means to perform low level serial communications, the Yocto-RS485 can work at a superior abstraction level. It can autonomously question a device through the serial port and present the values read as measures, in the same manner as all the Yoctopuce sensors. This includes the possibility to store the measures on the internal flash memory (data logger). Potentially, this enables you to transform any device equipped with a serial port into a native Yoctopuce sensor, with all the advantages this brings in terms of ease for software integration.

The Yocto-RS485 can automatically send and receive data on the serial port.

6.1. Communication jobs

The Yocto-RS485 contains a file system in which you can store jobs, which are in fact simple text files in the JSON format. A job describes write and read actions to be performed on the serial port. In the VirtualHub interface, the window describing the Yocto-RS485 properties allows you to select which job must be run, while the configuration window enables you to select which job must be run when the module starts. The Yocto-RS485 runs only one job at a time, but a job can perform actions in parallel.

Job structure

A job is essentially a set of tasks which are independent from one another. Each task can send data on the serial port and/or react to the arrival of data on the serial port.

Job definition and management

You can define jobs with the VirtualHub, in the Yocto-RS485 configuration window. Click on the manage files button and a window containing the list of defined jobs appears.

Job management window

This window enables you to select which job to run, to edit, or to delete. It also allows you to define a new job, either with the help of an interface or by directly uploading it on the module file system. To create a new job, click on define a new job. This opens the job creation window.

Job creation window

As a job is only a set of tasks, this window only allows you to give a name to the job and to manage the tasks it contains.

Creating a job by software

While there is no explicit API to define a job by software, a job is only a text file put in the file system of the Yocto-RS485. To configure the Yocto-RS485 by software, you simply need to upload the correct file on the Yocto-RS485 with the YFiles class and to program its running with the selectJob() or set_startupJob() functions of the YSerialPort class. The easiest way to create a job file without risking to make an error consists in using the VirtualHub to configure the desired job on a Yocto-RS485 module, and then to download the corresponding file.

6.2. Tasks

Each task is a simple list of commands to run sequentially: sending data on the serial port, waiting, reading data, and so on. There are two types of tasks: reactive tasks and periodic tasks.

Reactive tasks

A reactive task is triggered by the device connected to the Yocto-RS485: the task is automatically run as soon as data corresponding to predefined patterns appear on the port. Most often, a task simply consists in interpreting these data and in assigning them to one or several genericSensor functions available on the Yocto-RS485. Reactive tasks are particularly useful to interface devices that send a continuous flow of measures on their serial port. If the module detects data with a pattern corresponding to two distinct tasks, both tasks are run in parallel.

The VirtualHub allows you to easily create a good number of reactive tasks, such as:

Reading a numerical value in numeral or hexadecimal format
Reading GPS data in NMEA format
Reading a list of data in the CVS format
Detecting a MODBUS write operation
Detecting a MODBUS read operation

But you can also define personalized tasks by typing the task commands directly.

Reactive task creation interface

You can assign data that are read to any Yocto-RS485 genericSensor functions. From the developer stand point, the device that is connected to the Yocto-RS485 through its serial port appears like any usual Yoctopuce sensor. All the normal Yoctopuce sensor features (callbacks, data logger, averaging, and so on) are then available without any additional effort.

Beware, the serial protocol defined in the Yocto-RS485 configuration must correspond to the needs of the job. For instant, you cannot detect a MODBUS transaction if the Yocto-RS485 is configured in line-based ASCII mode.

Periodic tasks

A periodic task is a task that is run at a regular interval, at the Yocto-RS485 initiative. They are generally used to send commands to the device connected to the Yocto-RS485. Here again, the VirtualHub allows you to easily define a number of common tasks:

Sending text data
Sending binary data
Performing a MODBUS write operation
Performing a MODBUS read operation
Performing a read operation through a SCPI command

You can also define a task manually, one command after the other, or start by using a predefined task as above and edit it afterwards to add commands.

You can also assign data read in a periodic task to the Yocto-RS485 genericSensor functions. Beware, the serial protocol defined in the Yocto-RS485 configuration must correspond to the needs of the job: for example, you cannot detect a MODBUS transaction if the Yocto-RS485 is configured in line-based ASCII mode.

Periodic task creation interface

Although periodic tasks are designed to be run at regular intervals, you can define a "periodic" task that is run only once. Periodic tasks are run in the order in which they are defined. You can therefore define a job containing a first non recurrent task to configure your device, and a second task, recurrent, to question it in a loop.

You can mix periodic and reactive tasks in a same job. You must however pay careful attention to their triggering events in order to prevent them from perturbing each other. The Yocto-RS485 always waits until the end of a periodic task before running the next one. However, reactive tasks can be triggered at any time, even in parallel to a periodic task.

6.3. Commands

You can use the following commands in a (periodic or reactive) task:

EXPECT

The expect command waits for the data corresponding to a given pattern to appear on the serial line. If the module is configured in binary mode, the correspondence is established on a hexadecimal representation of the binary data.

The expect command takes a character string as argument. We support some regular expressions:

. (dot) corresponds to any character
[] defines a union, for example [123a-z] corresponds to any character among 1...3,a...z
[^] defines an exclusion, for example [^,] corresponds to any character except the comma.
* allows repetition of the latest correspondence zero, once, or several times: .* corresponds to all the characters until the end of the line
+ allows repetition of the latest correspondence once or several times. For example, [0-9]+ corresponds to one or several digits.

Special expressions can decode and assign values to one of the device genericSensor:

($x:INT) allows you to recognize an integer value (base 10) and assigned it to the corresponding genericSensorX function. For example, {$3:INT} allows you to recognize an integer value and to assign it to the genericSensor3 function.
($x:FLOAT) allows you to recognize a decimal value (floating point number) that is assigned to the genericSensorX. function. Scientific notation (for example 1.25e-1) is supported.
($x:DDM) allows you to recognize a decimal value in degree-minute-decimal format as used by NMEA standard
($x:BYTE) allows you to recognize a value between 0 and 255 represented in hexadecimal, as for instance when using binary protocols. If the value is in the range -128...127, you should use ($x:SBYTE) instead (where the S stands for signed byte. The decoded value is assigned to the genericSensorX.
($x:WORD) or ($x:SWORD) allows you similarly to decode a 16-bit hexadecimal value, unsigned or signed, and assign the result to the genericSensorX. The byte order is expected to be the natural written byte order (big-endian), i.e. the most significant byte first like in 0104 to represent 260.
($x:WORDL) or ($x:SWORDL) allows you to decode in the same way a 16-bit hexadecimal unsigned or signed value with the bytes in little-endian order, i.e. with the least significant byte first (eg. 0401 to represent 260).
($x:DWORD) or ($x:SDWORD) allows you to decode in the same way a 32-bit hexadecimal unsigned or signed value in big-endian byte order.
($x:DWORDL) ou ($x:SDWORDL) allows you to decode in the same way a 32-bit hexadecimal unsigned or signed value in little-endian byte order.
($x:DWORDX) ou ($x:SDWORDX) allows you to decode in the same way a 32-bit hexadecimal unsigned or signed value in mixed-endian byte order: two 16-bit words, each of them in big-endian, but the least significant 16-bit word is put first and the most significant word is put second.
($x:HEX) allows you to decode a variable length hexadecimal number (1 to 4 byes in big-endian order), that is assigned to the genericSensorX.
($x:FLOAT16B) and ($x:FLOAT16L) allows you to decode a 16-bit floating point number encoded in hexadecimal according to IEEE 754, using big-endian or little-endian byte order.
($x:FLOAT16D) allows you to decode a floating point number encoded in hexadecimal on two bytes, with the first byte representing the mantissa and the second byte representing the decimal signed exponent.
($x:FLOAT32B) and ($x:FLOAT32L) allows you to decode a 32-bit floating point number encoded in hexadecimal according to IEEE 754, using big-endian or little-endian byte order.
($x:FLOAT32X) allows you to decode a 32-bit floating point number encoded in hexadecimal according to IEEE 754, using mixed-endian byte order, i.e. two 16-bit words, each of them in big-endian, but the least significant 16-bit word is put first and the most significant word is put second.

As the internal representation of floating point numbers in Yoctopuce devices is limited to 3 decimals, it is possible to change the magnitude of floating point numbers decoded by FLOAT, FLOAT16 and FLOAT32 expressions by prefixing them with a M to count in thousandths, or a U to count in millionths (U like micro), or a N to count in billionths (N like nano). For instance, when the value 1.3e-6 is recognized with expression ($1:UFLOAT), the value assigned to genericSensor1 is 1.3.

COMPUTE

The compute command can be used to perform intermediary computations based one previously parsed values. For instance the following code recognizes an integer and stores in a variable $t, then uses compute with this variable to convert it to Â°F and place the result in genericSensor1.

expect ($t:WORD) compute $1 = 32 + ($t * 9) / 5

You can use quite sophisticated mathematical expressions. Most usual mathematical operators are available, with the following precedence order:

`**`	raise to the power
`~ + - not`	complement, unary plus/minus, logical not
`* / % //`	multiply, divide, integer modulo, integer divide
`+ -`	add, subtract
`>> <<`	bitwise shift right and left
`&`	bitwise AND
`\| ^`	bitwise OR, XOR
`< <= >= >`	compare
`== <> !=`	test if equal or different
`and`	logical AND
`or`	logical OR

For convenience, some alternative operator symbols can be used:

`div mod`	can be used instead of / and %
`! && \|\|`	can be used instead of `not`, `and`, `or`

Comparison and logical operators can be used together with the conditional evaluation operator:

compute "($temp > 0 ? log($temp) : -9999)"

Standard math constants and functions are available as well:

`pi e`	the universal constants
`cos sin tan`	trigonometric functions
`acos asin atan atan2`	inverse trigonometric functions
`cosh sinh tanh`	hyperbolic functions
`exp log log10 pow sqr sqrt`	power and logarithmic functions
`ceil floor round frac fmod`	rounding functions
`fabs min max isnan isinf`	ranging functions

Computations are made on 32bit floating point numbers. Bitwise operators (| & >> etc.) are made on 32bit integers.

ASSERT

The assert command can be used to check if precondition is met before continuing a task. It takes as argument an arithmetic expression, and stops the task execution if the expression result is FALSE.

Similarly to the compute command, if the expression includes a syntax error or refers to an undefined variable, the task will be stopped as well, with an error message in the device logs. It is however possible to verify if a variable is defined without generating an error message using the special function isset(): assert !isset($init_done) writeline :RESET compute $init_done = 1

WAIT

The wait command waits for a given number of milliseconds before running the following command.

LOG

The log command displays a character string in the logs of the Yocto-RS485.

WRITE

The write command sends a character string as is on the serial line. The string is sent without additional carriage return.

WRITELINE

The writeLine command sends a character string on the serial line, followed by a line break (CR-LF).

WRITEHEX

The writeHex command sends a binary message on the serial line. The parameter is the hexadecimal representation of the message to be sent (lower and upper case are supported).

WRITEMODBUS

The writeModbus command sends a MODBUS command. The parameter is a hexadecimal representation of the command to be sent, without checksum. For example:

03050006ff00 = Slave 3, Set Coil (05), relay 7 (0006), activate (0xff00)
030600021000 = Slave 3, Set Register (06), register 30003 (0002), value 4096 (0x1000)

SETRTS

The setRTS command, available only on the Yocto-Serial and on the Yocto-RS232 when hardware flux control is disabled, makes it possible to manually drive the RTS line from within a task.

SETSS

The setSS command, available only on the Yocto-SPI when frame-based transmission is not active, makes it possible to manually drive the SS line from within a task.

SETPOWER

The setPower command, available only on the Yocto-Serial and on the Yocto-SPI, makes it possible to automatically drive the power supply output from within a task, for instance to power on/off an external sensor.

If, for a reason or another, a command generates an error, you can find the traces of this error in the logs of the Yocto-RS485.

6.4. The genericSensor functions

9 genericSensor functions are available in the Yocto-RS485. Jobs running on the module can freely assign them values. You can access these genericSensor functions from the Yoctopuce API with the YGenericSensor class. You can also configure these functions to tailor their behavior depending on the nature of the reported values.

genericSensor configuration window

Unit

You can define the measuring system in which the value stored by the genericSensor is specified.

Resolution

You can define the resolution in which the value reported by the genericSensor must be represented.

Mapping

You can automatically apply a linear transformation to the values stored in a genericSensor. Indeed, some devices do not directly provide a physical quantity on their serial output. Let us imagine a voltmeter transmitting values between 0 and 65535 for measures between 0 and 10V. You can have the genericSensor function automatically perform an inverse conversion as illustrated below.

Linear conversion example.

This mechanism is also very useful for automatic conversions, for instance to convert feet into meters.

6.5. Configuration example

Here is a job example to interface a commercially available sensor.

Schneider Electric Zelio REG48 Temperature Controller

The REG48 temperature controller family is equipped with a MODBUS interface. You can read the measured temperature in the corresponding input register, specified in the controller programming guide (chapter "Data Address Map"). In this particular case, it is register 41001.

Step 1

Configure the Yocto-RS485 in "MODBUS-RTU", with speed and parity corresponding to the configuration of your REG48 controller.

Step 2

Create a job containing a single periodic task that reads the 41001 input MODBUS register.

Task example to read the temperature on a REG48 MODBUS controller

Step 3

Configure the genericSensor1 with unit='C and resolution=0.1. The value read in the register is given in tenth of degree, you must therefore configure the mapping to perform a division by 10.

Configuration of the genericSensor function to display the temperature measured by the REG48.

Step 4

Run the job to check that it works by displaying the functions of each module in the VirtualHub main page. If the result is not what you expected, check the module logs.

7. Programming, general concepts

The Yoctopuce API was designed to be at the same time simple to use and sufficiently generic for the concepts used to be valid for all the modules in the Yoctopuce range, and this in all the available programming languages. Therefore, when you have understood how to drive your Yocto-RS485 with your favorite programming language, learning to use another module, even with a different language, will most likely take you only a minimum of time.

7.1. Programming paradigm

The Yoctopuce API is object oriented. However, for simplicity's sake, only the basics of object programming were used. Even if you are not familiar with object programming, it is unlikely that this will be a hinderance for using Yoctopuce products. Note that you will never need to allocate or deallocate an object linked to the Yoctopuce API: it is automatically managed.

There is one class per Yoctopuce function type. The name of these classes always starts with a Y followed by the name of the function, for example YTemperature, YRelay, YPressure, etc.. There is also a YModule class, dedicated to managing the modules themselves, and finally there is the static YAPI class, that supervises the global workings of the API and manages low level communications.

Structure of the Yoctopuce API.

The YSensor class

Each Yoctopuce sensor function has its dedicated class: YTemperature to measure the temperature, YVoltage to measure a voltage, YRelay to drive a relay, etc. However there is a special class that can do more: YSensor.

The YSensor class is the parent class for all Yoctopuce sensors, and can provide access to any sensor, regardless of its type. It includes methods to access all common functions. This makes it easier to create applications that use many different sensors. Moreover, if you create an application based on YSensor, it will work with all Yoctopuce sensors, even those which do no yet exist.

Programmation

In the Yoctopuce API, priority was put on the ease of access to the module functions by offering the possibility to make abstractions of the modules implementing them. Therefore, it is quite possible to work with a set of functions without ever knowing exactly which module are hosting them at the hardware level. This tremendously simplifies programming projects with a large number of modules.

From the programming stand point, your Yocto-RS485 is viewed as a module hosting a given number of functions. In the API, these functions are objects which can be found independently, in several ways.

Access to the functions of a module

Access by logical name

Each function can be assigned an arbitrary and persistent logical name: this logical name is stored in the flash memory of the module, even if this module is disconnected. An object corresponding to an Xxx function to which a logical name has been assigned can then be directly found with this logical name and the YXxx.FindXxx method. Note however that a logical name must be unique among all the connected modules.

Access by enumeration

You can enumerate all the functions of the same type on all the connected modules with the help of the classic enumeration functions FirstXxx and nextXxxx available for each YXxx class.

Access by hardware name

Each module function has a hardware name, assigned at the factory and which cannot be modified. The functions of a module can also be found directly with this hardware name and the YXxx.FindXxx function of the corresponding class.

Difference between Find and First

The YXxx.FindXxxx and YXxx.FirstXxxx methods do not work exactly the same way. If there is no available module, YXxx.FirstXxxx returns a null value. On the opposite, even if there is no corresponding module, YXxx.FindXxxx returns a valid object, which is not online but which could become so if the corresponding module is later connected.

Function handling

When the object corresponding to a function is found, its methods are available in a classic way. Note that most of these subfunctions require the module hosting the function to be connected in order to be handled. This is generally not guaranteed, as a USB module can be disconnected after the control software has started. The isOnline method, available in all the classes, is then very helpful.

Access to the modules

Even if it is perfectly possible to build a complete project while making a total abstraction of which function is hosted on which module, the modules themselves are also accessible from the API. In fact, they can be handled in a way quite similar to the functions. They are assigned a serial number at the factory which allows you to find the corresponding object with YModule.Find(). You can also assign arbitrary logical names to the modules to make finding them easier. Finally, the YModule class contains the YModule.FirstModule() and nextModule() enumeration methods allowing you to list the connected modules.

Functions/Module interaction

From the API standpoint, the modules and their functions are strongly uncorrelated by design. Nevertheless, the API provides the possibility to go from one to the other. Thus, the get_module() method, available for each function class, allows you to find the object corresponding to the module hosting this function. Inversely, the YModule class provides several methods allowing you to enumerate the functions available on a module.

7.2. The Yocto-RS485 module

The Yocto-RS485 is an isolated RS485 interface with built-in datalogger.

module : Module

attribute	type	modifiable ?
`productName`	String	read-only
`serialNumber`	String	read-only
`logicalName`	String	read-only
`productId`	Hexadecimal number	read-only
`productRelease`	Hexadecimal number	read-only
`firmwareRelease`	String	read-only
`persistentSettings`	Enumerated	read-only
`luminosity`	0..100%	read-only
`beacon`	On/Off	read-only
`upTime`	Time	read-only
`usbCurrent`	Used current (mA)	read-only
`rebootCountdown`	Integer	read-only
`userVar`	Integer	read-only

serialPort : SerialPort

attribute	type	modifiable ?
`logicalName`	String	read-only
`advertisedValue`	String	read-only
`rxCount`	Integer	read-only
`txCount`	Integer	read-only
`errCount`	Integer	read-only
`rxMsgCount`	Integer	read-only
`txMsgCount`	Integer	read-only
`lastMsg`	String	read-only
`currentJob`	String	read-only
`startupJob`	String	read-only
`jobMaxTask`	Integer	read-only
`jobMaxSize`	Integer	read-only
`command`	String	read-only
`protocol`	Type of messaging protocol	read-only
`voltageLevel`	Enumerated	read-only
`serialMode`	Serial parameters	read-only

genericSensor1 : GenericSensor
genericSensor2 : GenericSensor
genericSensor3 : GenericSensor
genericSensor4 : GenericSensor
genericSensor5 : GenericSensor
genericSensor6 : GenericSensor
genericSensor7 : GenericSensor
genericSensor8 : GenericSensor
genericSensor9 : GenericSensor

attribute	type	modifiable ?
`logicalName`	String	read-only
`advertisedValue`	String	read-only
`unit`	String	read-only
`currentValue`	Fixed-point number	read-only
`lowestValue`	Fixed-point number	read-only
`highestValue`	Fixed-point number	read-only
`currentRawValue`	Fixed-point number	read-only
`logFrequency`	Frequency	read-only
`reportFrequency`	Frequency	read-only
`advMode`	Enumerated	read-only
`calibrationParam`	Calibration parameters	read-only
`resolution`	Fixed-point number	read-only
`sensorState`	Integer	read-only
`signalValue`	Fixed-point number	read-only
`signalUnit`	String	read-only
`signalRange`	Value range	read-only
`valueRange`	Value range	read-only
`signalBias`	Fixed-point number	read-only
`signalSampling`	Enumerated	read-only
`enabled`	Boolean	read-only

dataLogger : DataLogger

attribute	type	modifiable ?
`logicalName`	String	read-only
`advertisedValue`	String	read-only
`currentRunIndex`	Integer	read-only
`timeUTC`	UTC time	read-only
`recording`	Enumerated	read-only
`autoStart`	On/Off	read-only
`beaconDriven`	On/Off	read-only
`usage`	0..100%	read-only
`clearHistory`	Boolean	read-only

files : Files

attribute	type	modifiable ?
`logicalName`	String	read-only
`advertisedValue`	String	read-only
`filesCount`	Integer	read-only
`freeSpace`	Integer	read-only

7.3. Module

Global parameters control interface for all Yoctopuce devices

The YModule class can be used with all Yoctopuce USB devices. It can be used to control the module global parameters, and to enumerate the functions provided by each module.

productName

Character string containing the commercial name of the module, as set by the factory.

serialNumber

Character string containing the serial number, unique and programmed at the factory. For a Yocto-RS485 module, this serial number always starts with RS485MK1. You can use the serial number to access a given module by software.

logicalName

Character string containing the logical name of the module, initially empty. This attribute can be modified at will by the user. Once initialized to an non-empty value, it can be used to access a given module. If two modules with the same logical name are in the same project, there is no way to determine which one answers when one tries accessing by logical name. The logical name is limited to 19 characters among A..Z,a..z,0..9,_, and -.

productId

USB device identifier of the module, preprogrammed to 72 at the factory.

productRelease

Release number of the module hardware, preprogrammed at the factory. The original hardware release returns value 1, revision B returns value 2, etc.

firmwareRelease

Release version of the embedded firmware, changes each time the embedded software is updated.

persistentSettings

State of persistent module settings: loaded from flash memory, modified by the user or saved to flash memory.

luminosity

Lighting strength of the informative leds (e.g. the Yocto-Led) contained in the module. It is an integer value which varies between 0 (LEDs turned off) and 100 (maximum led intensity). The default value is 50. To change the strength of the module LEDs, or to turn them off completely, you only need to change this value.

beacon

Activity of the localization beacon of the module.

upTime

Time elapsed since the last time the module was powered on.

usbCurrent

Current consumed by the module on the USB bus, in milli-amps.

rebootCountdown

Countdown to use for triggering a reboot of the module.

userVar

32bit integer variable available for user storage.

7.4. SerialPort

serial port control interface, available for instance in the Yocto-RS232, the Yocto-RS485-V2 or the Yocto-Serial

The YSerialPort class allows you to fully drive a Yoctopuce serial port. It can be used to send and receive data, and to configure communication parameters (baud rate, bit count, parity, flow control and protocol). Note that Yoctopuce serial ports are not exposed as virtual COM ports. They are meant to be used in the same way as all Yoctopuce devices.

logicalName

Character string containing the logical name of the serial port, initially empty. This attribute can be modified at will by the user. Once initialized to an non-empty value, it can be used to access the serial port directly. If two serial ports with the same logical name are used in the same project, there is no way to determine which one answers when one tries accessing by logical name. The logical name is limited to 19 characters among A..Z,a..z,0..9,_, and -.

advertisedValue

Short character string summarizing the current state of the serial port, that is automatically advertised up to the parent hub. For a serial port, the advertised value is a hexadecimal signature that changes after each character received. This signature is made of the lower 16 bits of the receive counter, plus the ASCII code of the last character received.

rxCount

Total number of bytes received since last reset.

txCount

Total number of bytes transmitted since last reset.

errCount

Total number of communication errors detected since last reset.

rxMsgCount

Total number of messages received since last reset.

txMsgCount

Total number of messages transmitted since last reset.

lastMsg

Last message fully received (for Line, Frame and Modbus protocols).

currentJob

Name of the job file currently in use.

startupJob

Name of the job file to use when the device is powered on.

jobMaxTask

Maximum number of tasks in a job that the device can handle.

jobMaxSize

Maximum size allowed for job files.

command

Magic attribute used to send commands to the serial port. If a command is not interpreted as expected, check the device logs.

protocol

Type of protocol used on the serial link.

voltageLevel

Voltage level used on the serial connection.

serialMode

Baud rate, data bits, parity, and stop bits.

7.5. GenericSensor

GenericSensor control interface, available for instance in the Yocto-0-10V-Rx, the Yocto-4-20mA-Rx, the Yocto-RS485-V2 or the Yocto-milliVolt-Rx

The YGenericSensor class allows you to read and configure Yoctopuce signal transducers. It inherits from YSensor class the core functions to read measurements, to register callback functions, to access the autonomous datalogger. This class adds the ability to configure the automatic conversion between the measured signal and the corresponding engineering unit.

logicalName

Character string containing the logical name of the generic sensor, initially empty. This attribute can be modified at will by the user. Once initialized to an non-empty value, it can be used to access the generic sensor directly. If two generic sensors with the same logical name are used in the same project, there is no way to determine which one answers when one tries accessing by logical name. The logical name is limited to 19 characters among A..Z,a..z,0..9,_, and -.

advertisedValue

Short character string summarizing the current state of the generic sensor, that is automatically advertised up to the parent hub. For a generic sensor, the advertised value is the current value of the measure.

unit

Short character string representing the measuring unit for the measured value.

currentValue

Current value of the measure, in the specified unit, as a floating point number.

lowestValue

Minimal value of the measure, in the specified unit, as a floating point number.

highestValue

Maximal value of the measure, in the specified unit, as a floating point number.

currentRawValue

Uncalibrated, unrounded raw value returned by the sensor, as a floating point number.

logFrequency

Datalogger recording frequency, or "OFF" when measures should not be stored in the data logger flash memory.

reportFrequency

Timed value notification frequency, or "OFF" when timed value notifications are disabled for this function.

advMode

Measuring mode for the advertised value pushed to the parent hub.

calibrationParam

Extra calibration parameters (for instance to compensate for the effects of an enclosure), as an array of 16 bit words.

resolution

Measure resolution (i.e. precision of the numeric representation, not necessarily of the measure itself).

sensorState

Sensor health state (zero when a current measure is available).

signalValue

Current value of the electrical signal measured by the sensor, as a floating point number.

signalUnit

Short character string representing the measuring unit of the electrical signal used by the sensor.

signalRange

Electric signal range used by the sensor.

valueRange

Physical value range measured by the sensor, used to convert the signal.

signalBias

Electric signal bias for zero shift adjustment.

signalSampling

Signal sampling method to use.

enabled

Activation state of the input.

7.6. DataLogger

DataLogger control interface, available on most Yoctopuce sensors.

A non-volatile memory for storing ongoing measured data is available on most Yoctopuce sensors. Recording can happen automatically, without requiring a permanent connection to a computer. The YDataLogger class controls the global parameters of the internal data logger. Recording control (start/stop) as well as data retreival is done at sensor objects level.

logicalName

Character string containing the logical name of the data logger, initially empty. This attribute can be modified at will by the user. Once initialized to an non-empty value, it can be used to access the data logger directly. If two data loggers with the same logical name are used in the same project, there is no way to determine which one answers when one tries accessing by logical name. The logical name is limited to 19 characters among A..Z,a..z,0..9,_, and -.

advertisedValue

Short character string summarizing the current state of the data logger, that is automatically advertised up to the parent hub. For a data logger, the advertised value is its recording state (ON or OFF).

currentRunIndex

Current run number, corresponding to the number of time the module was powered on with the dataLogger enabled at some point.

timeUTC

Current UTC time, in case it is desirable to bind an absolute time reference to the data stored by the data logger. This time must be set up by software.

recording

Activation state of the data logger. The data logger can be enabled and disabled at will, using this attribute, but its state on power on is determined by the autoStart persistent attribute. When the datalogger is enabled but not yet ready to record data, its state is set to PENDING.

autoStart

Automatic start of the data logger on power on. Setting this attribute ensures that the data logger is always turned on when the device is powered up, without need for a software command. Note: if the device doesn't have any time source at his disposal, it will wait for ~8 seconds before automatically starting to record.

beaconDriven

Synchronize the sate of the localization beacon and the state of the data logger. If this attribute is set, it is possible to start the recording with the Yocto-button or the attribute beacon of the function YModule. In the same way, if the attribute recording is changed, the sate of the localization beacon is updated. Note: when this attribute is set the localization beacon pulses slower than usual.

usage

Percentage of datalogger memory in use.

clearHistory

Attribute that can be set to true to clear recorded data.

7.7. Files

filesystem control interface, available for instance in the Yocto-Buzzer, the Yocto-Color-V2, the Yocto-RS485-V2 or the YoctoHub-Ethernet

The YFiles class is used to access the filesystem embedded on some Yoctopuce devices. This filesystem makes it possible for instance to design a custom web UI (for networked devices) or to add fonts (on display devices).

logicalName

Character string containing the logical name of the filesystem, initially empty. This attribute can be modified at will by the user. Once initialized to an non-empty value, it can be used to access the filesystem directly. If two filesystems with the same logical name are used in the same project, there is no way to determine which one answers when one tries accessing by logical name. The logical name is limited to 19 characters among A..Z,a..z,0..9,_, and -.

advertisedValue

Short character string summarizing the current state of the filesystem, that is automatically advertised up to the parent hub. For a filesystem, the advertised value is the number of files loaded in the filesystem.

filesCount

Number of files currently loaded in the filesystem.

freeSpace

Free space for uploading new files to the filesystem, in bytes.

7.8. What interface: Native, DLL or Service ?

There are several methods to control you Yoctopuce module by software.

Native control

In this case, the software driving your project is compiled directly with a library which provides control of the modules. Objectively, it is the simplest and most elegant solution for the end user. The end user then only needs to plug the USB cable and run your software for everything to work. Unfortunately, this method is not always available or even possible.

The application uses the native library to control the locally connected module

Native control by DLL

Here, the main part of the code controlling the modules is located in a DLL. The software is compiled with a small library which provides control of the DLL. It is the fastest method to code module support in a given language. Indeed, the "useful" part of the control code is located in the DLL which is the same for all languages: the effort to support a new language is limited to coding the small library which controls the DLL. From the end user stand point, there are few differences: one must simply make sure that the DLL is installed on the end user's computer at the same time as the main software.

The application uses the DLL to natively control the locally connected module

Control by service

Some languages do simply not allow you to easily gain access to the hardware layers of the machine. It is the case for Javascript, for instance. To deal with this case, Yoctopuce provides a solution in the form of a small piece of software called VirtualHub¹⁵. It can access the modules, and your application only needs to use a library which offers all necessary functions to control the modules via this VirtualHub. The end users will have to start the VirtualHub before running the project control software itself, unless they decide to install the hub as a service/deamon, in which case the VirtualHub starts automatically when the machine starts up.

The application connects itself to the VirtualHub to gain access to the module

The service control method comes with a non-negligible advantage: the application does not need to run on the machine on which the modules are connected. The application can very well be located on another machine which connects itself to the service to drive the modules. Moreover, the native libraries and DLL mentioned above are also able to connect themselves remotely to one or several machines running VirtualHub.

When a VirtualHub is used, the control application does not need to reside on the same machine as the module.

Whatever the selected programming language and the control paradigm used, programming itself stays strictly identical. From one language to another, functions bear exactly the same name, and have the same parameters. The only differences are linked to the constraints of the languages themselves.

Language	Native	Native with DLL	VirtualHub
C++	✔	✔	✔
Objective-C	✔	-	✔
Delphi	-	✔	✔
Python	-	✔	✔
VisualBasic .Net	-	✔	✔
C# .Net	-	✔	✔
C# UWP	✔	-	✔
EcmaScript / JavaScript	-	-	✔
PHP	-	-	✔
Java	-	✔	✔
Java for Android	✔	-	✔
Command line	✔	-	✔
LabVIEW	-	✔	✔

Support methods for different languages

Limitations of the Yoctopuce libraries

Natives et DLL libraries have a technical limitation. On the same computer, you cannot concurrently run several applications accessing Yoctopuce devices directly. If you want to run several projects on the same computer, make sure your control applications use Yoctopuce devices through a VirtualHub software. The modification is trivial: it is just a matter of parameter change in the yRegisterHub() call.

7.9. Programming, where to start?

At this point of the user's guide, you should know the main theoretical points of your Yocto-RS485. It is now time to practice. You must download the Yoctopuce library for your favorite programming language from the Yoctopuce web site¹⁶. Then skip directly to the chapter corresponding to the chosen programming language.

All the examples described in this guide are available in the programming libraries. For some languages, the libraries also include some complete graphical applications, with their source code.

When you have mastered the basic programming of your module, you can turn to the chapter on advanced programming that describes some techniques that will help you make the most of your Yocto-RS485.

8. Using the Yocto-RS485 in command line

When you want to perform a punctual operation on your Yocto-RS485, such as reading a value, assigning a logical name, and so on, you can obviously use the Virtual Hub, but there is a simpler, faster, and more efficient method: the command line API.

The command line API is a set of executables, one by type of functionality offered by the range of Yoctopuce products. These executables are provided pre-compiled for all the Yoctopuce officially supported platforms/OS. Naturally, the executable sources are also provided¹⁷.

8.1. Installing

Download the command line API¹⁸. You do not need to run any setup, simply copy the executables corresponding to your platform/OS in a directory of your choice. You may add this directory to your PATH variable to be able to access these executables from anywhere. You are all set, you only need to connect your Yocto-RS485, open a shell, and start working by typing for example:

C:\>YSerialPort any modbusReadInputRegisters 2 1000 1

C:\>YSerialPort any modbusWriteBits 2 16 1

To use the command API on Linux, you need either have root privileges or to define an udev rule for your system. See the Troubleshooting chapter for more details.

8.2. Use: general description

All the command line API executables work on the same principle. They must be called the following way

C:\>Executable [options] [target] command [parameter]

[options] manage the global workings of the commands, they allow you, for instance, to pilot a module remotely through the network, or to force the module to save its configuration after executing the command.

[target] is the name of the module or of the function to which the command applies. Some very generic commands do not need a target. You can also use the aliases "any" and "all", or a list of names separated by comas without space.

command is the command you want to run. Almost all the functions available in the classic programming APIs are available as commands. You need to respect neither the case nor the underlined characters in the command name.

[parameters] logically are the parameters needed by the command.

At any time, the command line API executables can provide a rather detailed help. Use for instance:

C:\>executable /help

to know the list of available commands for a given command line API executable, or even:

C:\>executable command /help

to obtain a detailed description of the parameters of a command.

8.3. Control of the SerialPort function

To control the SerialPort function of your Yocto-RS485, you need the YSerialPort executable file.

For instance, you can launch:

C:\>YSerialPort any modbusReadInputRegisters 2 1000 1

C:\>YSerialPort any modbusWriteBits 2 16 1

This example uses the "any" target to indicate that we want to work on the first SerialPort function found among all those available on the connected Yoctopuce modules when running. This prevents you from having to know the exact names of your function and of your module.

But you can use logical names as well, as long as you have configured them beforehand. Let us imagine a Yocto-RS485 module with the RS485MK1-123456 serial number which you have called "MyModule", and its serialPort function which you have renamed "MyFunction". The five following calls are strictly equivalent (as long as MyFunction is defined only once, to avoid any ambiguity).

C:\>YSerialPort RS485MK1-123456.serialPort describe

C:\>YSerialPort RS485MK1-123456.MyFunction describe

C:\>YSerialPort MyModule.serialPort describe

C:\>YSerialPort MyModule.MyFunction describe

C:\>YSerialPort MyFunction describe

To work on all the SerialPort functions at the same time, use the "all" target.

C:\>YSerialPort all describe

For more details on the possibilities of the YSerialPort executable, use:

C:\>YSerialPort /help

8.4. Control of the module part

Each module can be controlled in a similar way with the help of the YModule executable. For example, to obtain the list of all the connected modules, use:

C:\>YModule inventory

You can also use the following command to obtain an even more detailed list of the connected modules:

C:\>YModule all describe

Each xxx property of the module can be obtained thanks to a command of the get_xxxx() type, and the properties which are not read only can be modified with the set_xxx() command. For example:

C:\>YModule RS485MK1-12346 set_logicalName MonPremierModule

C:\>YModule RS485MK1-12346 get_logicalName

Changing the settings of the module

When you want to change the settings of a module, simply use the corresponding set_xxx command. However, this change happens only in the module RAM: if the module restarts, the changes are lost. To store them permanently, you must tell the module to save its current configuration in its nonvolatile memory. To do so, use the saveToFlash command. Inversely, it is possible to force the module to forget its current settings by using the revertFromFlash method. For example:

C:\>YModule RS485MK1-12346 set_logicalName MonPremierModule
C:\>YModule RS485MK1-12346 saveToFlash

Note that you can do the same thing in a single command with the -s option.

C:\>YModule -s RS485MK1-12346 set_logicalName MonPremierModule

Warning: the number of write cycles of the nonvolatile memory of the module is limited. When this limit is reached, nothing guaranties that the saving process is performed correctly. This limit, linked to the technology employed by the module micro-processor, is located at about 100000 cycles. In short, you can use the saveToFlash() function only 100000 times in the life of the module. Make sure you do not call this function within a loop.

8.5. Limitations

The command line API has the same limitation than the other APIs: there can be only one application at a given time which can access the modules natively. By default, the command line API works in native mode.

You can easily work around this limitation by using a Virtual Hub: run the VirtualHub¹⁹ on the concerned machine, and use the executables of the command line API with the -r option. For example, if you use:

C:\>YModule inventory

you obtain a list of the modules connected by USB, using a native access. If another command which accesses the modules natively is already running, this does not work. But if you run a Virtual Hub, and you give your command in the form:

C:\>YModule -r 127.0.0.1 inventory

it works because the command is not executed natively anymore, but through the Virtual Hub. Note that the Virtual Hub counts as a native application.

9. Using Yocto-RS485 with JavaScript / EcmaScript

EcmaScript is the official name of the standardized version of the web-oriented programming language commonly referred to as JavaScript. This Yoctopuce library take advantages of advanced features introduced in EcmaScript 2017. It has therefore been named Library for JavaScript / EcmaScript 2017 to differentiate it from the previous Library for JavaScript, now deprecated in favor of this new version.

This library provides access to Yoctopuce devices for modern JavaScript engines. It can be used within a browser as well as with Node.js. The library will automatically detect upon initialization whether the runtime environment is a browser or a Node.js virtual machine, and use the most appropriate system libraries accordingly.

Asynchronous communication with the devices is handled across the whole library using Promise objects, leveraging the new EcmaScript 2017 async / await non-blocking syntax for asynchronous I/O (see below). This syntax is now available out-of-the-box in most Javascript engines. No transpilation is needed: no Babel, no jspm, just plain Javascript. Here is your favorite engines minimum version needed to run this code. All of them are officially released at the time we write this document.

Node.js v7.6 and later
Firefox 52
Opera 42 (incl. Android version)
Chrome 55 (incl. Android version)
Safari 10.1 (incl. iOS version)
Android WebView 55
Google V8 Javascript engine v5.5

If you need backward-compatibility with older releases, you can always run Babel to transpile your code and the library to older standards, as described a few paragraphs below.

We don't suggest using jspm 0.17 anymore since that tool is still in Beta after 18 month, and having to use an extra tool to implement our library is pointless now that async / await are part of the standard.

9.1. Blocking I/O versus Asynchronous I/O in JavaScript

JavaScript is single-threaded by design. That means, if a program is actively waiting for the result of a network-based operation such as reading from a sensor, the whole program is blocked. In browser environments, this can even completely freeze the user interface. For this reason, the use of blocking I/O in JavaScript is strongly discouraged nowadays, and blocking network APIs are getting deprecated everywhere.

Instead of using parallel threads, JavaScript relies on asynchronous I/O to handle operations with a possible long timeout: whenever a long I/O call needs to be performed, it is only triggered and but then the code execution flow is terminated. The JavaScript engine is therefore free to handle other pending tasks, such as UI. Whenever the pending I/O call is completed, the system invokes a callback function with the result of the I/O call to resume execution of the original execution flow.

When used with plain callback functions, as pervasive in Node.js libraries, asynchronous I/O tend to produce code with poor readability, as the execution flow is broken into many disconnected callback functions. Fortunately, new methods have emerged recently to improve that situation. In particular, the use of Promise objects to abstract and work with asynchronous tasks helps a lot. Any function that makes a long I/O operation can return a Promise, which can be used by the caller to chain subsequent operations in the same flow. Promises are part of EcmaScript 2015 standard.

Promise objects are good, but what makes them even better is the new async / await keywords to handle asynchronous I/O:

a function declared async will automatically encapsulate its result as a Promise
within an async function, any function call prefixed with by await will chain the Promise returned by the function with a promise to resume execution of the caller
any exception during the execution of an async function will automatically invoke the Promise failure continuation

Long story made short, async and await make it possible to write EcmaScript code with all benefits of asynchronous I/O, but without breaking the code flow. It is almost like multi-threaded execution, except that control switch between pending tasks only happens at places where the await keyword appears.

We have therefore chosen to write our new EcmaScript library using Promises and async functions, so that you can use the friendly await syntax. To keep it easy to remember, all public methods of the EcmaScript library are async, i.e. return a Promise object, except:

GetTickCount(), because returning a time stamp asynchronously does not make sense...
FindModule(), FirstModule(), nextModule(), ... because device detection and enumeration always work on internal device lists handled in background, and does not require immediate asynchronous I/O.

9.2. Using Yoctopuce library for JavaScript / EcmaScript 2017

JavaScript is one of those languages which do not generally allow you to directly access the hardware layers of your computer. Therefore the library can only be used to access network-enabled devices (connected through a YoctoHub), or USB devices accessible through Yoctopuce TCP/IP to USB gateway, named VirtualHub.

Go to the Yoctopuce web site and download the following items:

The Javascript / EcmaScript 2017 programming library²⁰
The VirtualHub software²¹ for Windows, Mac OS X or Linux, depending on your OS

Extract the library files in a folder of your choice, you will find many of examples in it. Connect your modules and start the VirtualHub software. You do not need to install any driver.

Using the official Yoctopuce library for node.js

Start by installing the latest Node.js version (v7.6 or later) on your system. It is very easy. You can download it from the official web site: http://nodejs.org. Make sure to install it fully, including npm, and add it to the system path.

To give it a try, go into one of the example directory (for instance example_nodejs/Doc-Inventory). You will see that it include an application description file (package.json) and a source file (demo.js). To download and setup the libraries needed by this example, just run:

npm install

Once done, you can start the example file using:

node demo.js

Using a local copy of the Yoctopuce library with node.js

If for some reason you need to make changes to the Yoctopuce library, you can easily configure your project to use the local copy in the lib/ subdirectory rather than the official npm package. In order to do so, simply type the following command in your project directory:

npm link ../../lib

Using the Yoctopuce library within a browser (HTML)

For HTML examples, it is even simpler: there is nothing to install. Each example is a single HTML file that you can open in a browser to try it. In this context, loading the Yoctopuce library is no different from any standard HTML script include tag.

Using the Yoctoluce library on older JavaScript engines

If you need to run this library on older JavaScript engines, you can use Babel²² to transpile your code and the library into older JavaScript standards. To install Babel with typical settings, simply use:

npm instal -g babel-cli
npm instal babel-preset-env

You would typically ask Babel to put the transpiled files in another directory, named compat for instance. Your files and all files of the Yoctopuce library should be transpiled, as follow:

babel --presets env demo.js --out-dir compat/
babel --presets env ../../lib --out-dir compat/

Although this approach is based on node.js toolchain, it actually works as well for transpiling JavaScript files for use in a browser. The only thing that you cannot do so easily is transpiling JavaScript code embedded directly in an HTML page. You have to use an external script file for using EcmaScript 2017 syntax with Babel.

Babel has many smart features, such as a watch mode that will automatically refresh transpiled files whenever the source file is changed, but this is beyond the scope of this note. You will find more in Babel documentation.

Backward-compatibility with the old JavaScript library

This new library is not fully backward-compatible with the old JavaScript library, because there is no way to transparently map the old blocking API to the new asynchronous API. The method names however are the same, and old synchronous code can easily be made asynchronous just by adding the proper await keywords before the method calls. For instance, simply replace:

beaconState = module.get_beacon();

beaconState = await module.get_beacon();

Apart from a few exceptions, most XXX_async redundant methods have been removed as well, as they would have introduced confusion on the proper way of handling asynchronous behaviors. It is however very simple to get an async method to invoke a callback upon completion, using the returned Promise object. For instance, you can replace:

module.get_beacon_async(callback, myContext);

module.get_beacon().then(function(res) { callback(myContext, module, res); });

In some cases, it might be desirable to get a sensor value using a method identical to the old synchronous methods (without using Promises), even if it returns a slightly outdated cached value since I/O is not possible. For this purpose, the EcmaScript library introduce new classes called synchronous proxies. A synchronous proxy is an object that mirrors the most recent state of the connected class, but can be read using regular synchronous function calls. For instance, instead of writing:

async function logInfo(module)
{
console.log('Name: '+await module.get_logicalName());
console.log('Beacon: '+await module.get_beacon());
}

...
logInfo(myModule);
...

you can use:

function logInfoProxy(moduleSyncProxy)
{
console.log('Name: '+moduleProxy.get_logicalName());
console.log('Beacon: '+moduleProxy.get_beacon());
}

logInfoSync(await myModule.get_syncProxy());

You can also rewrite this last asynchronous call as:

myModule.get_syncProxy().then(logInfoProxy);

9.3. Control of the SerialPort function

A few lines of code are enough to use a Yocto-RS485. Here is the skeleton of a JavaScript code snipplet to use the SerialPort function.

// For Node.js, we use function require()
// For HTML, we would use <script src="...">
require('yoctolib-es2017/yocto_api.js');
require('yoctolib-es2017/yocto_serialport.js');

[...]
// Get access to your device, through the VirtualHub running locally
await YAPI.RegisterHub('127.0.0.1');
[...]

// Retrieve the object used to interact with the device
var serialport = YSerialPort.FindSerialPort("RS485MK1-123456.serialPort");

// Check that the module is online to handle hot-plug
if(await serialport.isOnline())
{
// Use serialport.get_serialMode()
[...]
}

Let us look at these lines in more details.

yocto_api and yocto_serialport import

These two import provide access to functions allowing you to manage Yoctopuce modules. yocto_api is always needed, yocto_serialport is necessary to manage modules containing a serial port, such as Yocto-RS485. Other imports can be useful in other cases, such as YModule which can let you enumerate any type of Yoctopuce device.

YAPI.RegisterHub

The RegisterHub method allows you to indicate on which machine the Yoctopuce modules are located, more precisely on which machine the VirtualHub software is running. In our case, the 127.0.0.1:4444 address indicates the local machine, port 4444 (the standard port used by Yoctopuce). You can very well modify this address, and enter the address of another machine on which the VirtualHub software is running, or of a YoctoHub. If the host cannot be reached, this function will trigger an exception.

YSerialPort.FindSerialPort

The FindSerialPort method allows you to find a serial port from the serial number of the module on which it resides and from its function name. You can also use logical names, as long as you have initialized them. Let us imagine a Yocto-RS485 module with serial number RS485MK1-123456 which you have named "MyModule", and for which you have given the serialPort function the name "MyFunction". The following five calls are strictly equivalent, as long as "MyFunction" is defined only once.

serialport = YSerialPort.FindSerialPort("RS485MK1-123456.serialPort")
serialport = YSerialPort.FindSerialPort("RS485MK1-123456.MaFonction")
serialport = YSerialPort.FindSerialPort("MonModule.serialPort")
serialport = YSerialPort.FindSerialPort("MonModule.MaFonction")
serialport = YSerialPort.FindSerialPort("MaFonction")

YSerialPort.FindSerialPort returns an object which you can then use at will to control the serial port.

isOnline

The isOnline() method of the object returned by FindSerialPort allows you to know if the corresponding module is present and in working order.

modbusWrite* and modbusRead*

The modbusWrite*() and modbusRead*() method of the object returned by YFindSerialPort.FindSerialPort provides MODBUS communication overs the serial port.

A real example, for Node.js

Open a command window (a terminal, a shell...) and go into the directory example_nodejs/Doc-GettingStarted-Yocto-RS485 within Yoctopuce library for JavaScript / EcmaScript 2017. In there, you will find a file named demo.js with the sample code below, which uses the functions explained above, but this time used with all side materials needed to make it work nicely as a small demo.

If your Yocto-RS485 is not connected on the host running the browser, replace in the example the address 127.0.0.1 by the IP address of the host on which the Yocto-RS485 is connected and where you run the VirtualHub.

"use strict";

require('yoctolib-es2017/yocto_api.js');
require('yoctolib-es2017/yocto_serialport.js');

let serialPort;
let target = {slave: 0, reg: 0};
let g_step = 1;
let rl;
async function startDemo() {
const readline = YAPI._nodeRequire('readline');

await YAPI.LogUnhandledPromiseRejections();
await YAPI.DisableExceptions();

// Setup the API to use the VirtualHub on local machine
let errmsg = new YErrorMsg();
if (await YAPI.RegisterHub('127.0.0.1', errmsg) != YAPI.SUCCESS) {
console.log('Cannot contact VirtualHub on 127.0.0.1: ' + errmsg.msg);
return;
}

// Select specified device, or use first available one
let serial = process.argv[process.argv.length - 1];
if (serial[8] != '-') {
// by default use any connected module suitable for the demo
let anyserial = YSerialPort.FirstSerialPort();
if (anyserial) {
let module = await anyserial.module();
serial = await module.get_serialNumber();
} else {
console.log('No matching module connected, check cable !');
return;
}
}
console.log('Using device ' + serial);
serialPort = YSerialPort.FirstSerialPort();
rl = readline.createInterface({
input: process.stdin,
output: process.stdout
});
console.log('Please enter the MODBUS slave address (1...255)');
console.log('Slave:');
rl.on('line', handleInput);
}

async function handleInput(chunk) {
var val = parseInt(chunk);
switch (g_step) {
case 1:
if (val < 1 || val > 255) {
console.log("invalid slave number");
} else {
target.slave = val;
g_step++;
console.log("Slave = " + target.slave);
console.log("Please select a Coil No (>=1), Input Bit No (>=10001+),");
console.log(" Register No (>=30001) or Input Register No (>=40001)");
console.log("No: ");
}
break;
case 2:
if (val < 1 || val >= 50000 || (val % 10000) == 0) {
console.log("invalid register number");
} else {
target.reg = val;
await printModbusValue(target.slave, target.reg);
g_step++;
console.log("Press ENTER to read again, Q to quit:");
if ((target.reg % 30000) < 10000) {
console.log(" or enter a new value:");
}
}
break;
case 3:
if (chunk.charAt(0) == 'q' || chunk.charAt(0) == 'Q') {
await YAPI.FreeAPI();
rl.close();
break;
}
if (chunk.charAt(0) != 'r' && chunk.charAt(0) != 'R' && (target.reg % 30000) < 10000) {
if (target.reg >= 30001) {
await serialPort.modbusWriteRegister(target.slave, target.reg - 30001, val);
} else {
await serialPort.modbusWriteBit(target.slave, target.reg - 1, val);
}
}
await printModbusValue(target.slave, target.reg);
console.log("Press R to read again, Q to quit");
if ((target.reg % 30000) < 10000) {
console.log(" or enter a new value");
}
console.log(": ");
break;
default:
console.log('data: ' + chunk);
}
}

async function printModbusValue(slave, reg) {
var val;
console.log("reg=" + reg + " slave=" + slave);
if (reg >= 40001) {
val = (await serialPort.modbusReadRegisters(slave, reg - 40001, 1))[0];
} else if (reg >= 30001) {
val = (await serialPort.modbusReadInputRegisters(slave, reg - 30001, 1))[0];
} else if (reg >= 10001) {
val = (await serialPort.modbusReadInputBits(slave, reg - 10001, 1))[0];
} else {
val = (await serialPort.modbusReadBits(slave, reg - 1, 1))[0];
}
console.log("Current value: " + val);
return val;
}

startDemo();

As explained at the beginning of this chapter, you need to have Node.js v7.6 or later installed to try this example. When done, you can type the following two commands to automatically download and install the dependencies for building this example:

npm install

You can the start the sample code within Node.js using the following command, replacing the [...] by the arguments that you want to pass to the demo code:

node demo.js [...]

Same example, but this time running in a browser

If you want to see how to use the library within a browser rather than with Node.js, switch to the directory example_html/Doc-GettingStarted-Yocto-RS485. You will find there a single HTML file, with a JavaScript section similar to the code above, but with a few changes since it has to interact through an HTML page rather than through the JavaScript console.

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Hello World</title>
<script src="../../lib/yocto_api.js"></script>
<script src="../../lib/yocto_serialport.js"></script>
<script>
let serialPort;
let slave;
let reg;
async function startDemo() {

await YAPI.LogUnhandledPromiseRejections();
await YAPI.DisableExceptions();

// Setup the API to use the VirtualHub on local machine
let errmsg = new YErrorMsg();
if (await YAPI.RegisterHub('127.0.0.1', errmsg) != YAPI.SUCCESS) {
alert('Cannot contact VirtualHub on 127.0.0.1: ' + errmsg.msg);
return;
}
refresh();
}
async function refresh() {
// Select specified device, or use first available one
let serial = document.getElementById('serial').value;
if (serial == '') {
// by default use any connected module suitable for the demo
let anyserial = YSerialPort.FirstSerialPort();
if (anyserial) {
let module = await anyserial.module();
serial = await module.get_serialNumber();
document.getElementById('serial').value = serial;
}
}
serialPort = YSerialPort.FirstSerialPort();
if (await serialPort.isOnline()) {
// display motor status
document.getElementById('msg').value = '';
document.getElementById('main').style.display = '';
} else {
document.getElementById('msg').value = 'Module not connected';
}
setTimeout(refresh, 500);
}

function slavechanged() {
slave = parseInt(document.getElementById('slaveinput').value);
if (slave > 0) {
document.getElementById('slaveinput').style.display = 'none';
document.getElementById('slavevalue').innerHTML = slave;
document.getElementById('regspan').style.display = '';
}
}

async function regchanged() {
reg = parseInt(document.getElementById('reginput').value);
let res;
if (reg > 0) {
let value = await modbus_readvalue(slave, reg);
document.getElementById('reginput').style.display = 'none';
document.getElementById('regvalue').innerHTML = reg;
document.getElementById('valuespan').style.display = '';
document.getElementById('value').innerHTML = value;
}
}

async function modbus_readvalue(slave, reg) {
let val;
if (reg >= 40001) {
val = (await serialPort.modbusReadRegisters(slave, reg - 40001, 1))[0];
} else if (reg >= 30001) {
val = (await serialPort.modbusReadInputRegisters(slave, reg - 30001, 1))[0];
} else if (reg >= 10001) {
val = (await serialPort.modbusReadInputBits(slave, reg - 10001, 1))[0];
} else {
val = (await serialPort.modbusReadBits(slave, reg - 1, 1))[0];
}
console.log("Current value: " + val);
return val;
}

startDemo();
</script>
</head>
<body>
Module to use: <input id='serial'>
<input id='msg' style='color:red;border:none;' readonly><br>
<span id='main' style='display:none'>
Please enter the MODBUS slave address (1...255)<br>
slave:<input id='slaveinput' onchange='javascript:slavechanged()'>
<span id='slavevalue'></span><br>
<span id='regspan' style='display:none'>
Please select a Coil No (>=1), Input Bit No (>=10001+)<br>
Input Register No (>=30001) or Register No (>=40001)<br>
No: <input id='reginput' onchange='javascript:regchanged()'>
<span id='regvalue'></span><br>
</span>
<span id='valuespan' style='display:none'>
CurrentValue: <span id='value'></span><br>
</span>
</body>
</html>

No installation is needed to run this example, all you have to do is open the HTML file using a web browser,

9.4. Control of the module part

Each module can be controlled in a similar manner, you can find below a simple sample program displaying the main parameters of the module and enabling you to activate the localization beacon.

"use strict";

require('yoctolib-es2017/yocto_api.js');

async function startDemo(args)
{
await YAPI.LogUnhandledPromiseRejections();

// Setup the API to use the VirtualHub on local machine
let errmsg = new YErrorMsg();
if(await YAPI.RegisterHub('127.0.0.1', errmsg) != YAPI.SUCCESS) {
console.log('Cannot contact VirtualHub on 127.0.0.1: '+errmsg.msg);
return;
}

// Select the relay to use
let module = YModule.FindModule(args[0]);
if(await module.isOnline()) {
if(args.length > 1) {
if(args[1] == 'ON') {
await module.set_beacon(YModule.BEACON_ON);
} else {
await module.set_beacon(YModule.BEACON_OFF);
}
}
console.log('serial: '+await module.get_serialNumber());
console.log('logical name: '+await module.get_logicalName());
console.log('luminosity: '+await module.get_luminosity()+'%');
console.log('beacon: '+(await module.get_beacon()==YModule.BEACON_ON?'ON':'OFF'));
console.log('upTime: '+parseInt(await module.get_upTime()/1000)+' sec');
console.log('USB current: '+await module.get_usbCurrent()+' mA');
console.log('logs:');
console.log(await module.get_lastLogs());
} else {
console.log("Module not connected (check identification and USB cable)\n");
}
await YAPI.FreeAPI();
}

if(process.argv.length < 2) {
console.log("usage: node demo.js <serial or logicalname> [ ON | OFF ]");
} else {
startDemo(process.argv.slice(2));
}

Each property xxx of the module can be read thanks to a method of type get_xxxx(), and properties which are not read-only can be modified with the help of the set_xxx() method. For more details regarding the used functions, refer to the API chapters.

Changing the module settings

When you want to modify the settings of a module, you only need to call the corresponding set_xxx() function. However, this modification is performed only in the random access memory (RAM) of the module: if the module is restarted, the modifications are lost. To memorize them persistently, it is necessary to ask the module to save its current configuration in its permanent memory. To do so, use the saveToFlash() method. Inversely, it is possible to force the module to forget its current settings by using the revertFromFlash() method. The short example below allows you to modify the logical name of a module.

"use strict";

require('yoctolib-es2017/yocto_api.js');

async function startDemo(args)
{
await YAPI.LogUnhandledPromiseRejections();

// Setup the API to use the VirtualHub on local machine
let errmsg = new YErrorMsg();
if(await YAPI.RegisterHub('127.0.0.1', errmsg) != YAPI.SUCCESS) {
console.log('Cannot contact VirtualHub on 127.0.0.1: '+errmsg.msg);
return;
}

// Select the relay to use
let module = YModule.FindModule(args[0]);
if(await module.isOnline()) {
if(args.length > 1) {
let newname = args[1];
if (!await YAPI.CheckLogicalName(newname)) {
console.log("Invalid name (" + newname + ")");
process.exit(1);
}
await module.set_logicalName(newname);
await module.saveToFlash();
}
console.log('Current name: '+await module.get_logicalName());
} else {
console.log("Module not connected (check identification and USB cable)\n");
}
await YAPI.FreeAPI();
}

if(process.argv.length < 2) {
console.log("usage: node demo.js <serial> [newLogicalName]");
} else {
startDemo(process.argv.slice(2));
}

Listing the modules

Obtaining the list of the connected modules is performed with the YModule.FirstModule() function which returns the first module found. Then, you only need to call the nextModule() function of this object to find the following modules, and this as long as the returned value is not null. Below a short example listing the connected modules.

"use strict";

require('yoctolib-es2017/yocto_api.js');

async function startDemo()
{
await YAPI.LogUnhandledPromiseRejections();
await YAPI.DisableExceptions();

// Setup the API to use the VirtualHub on local machine
let errmsg = new YErrorMsg();
if (await YAPI.RegisterHub('127.0.0.1', errmsg) != YAPI.SUCCESS) {
console.log('Cannot contact VirtualHub on 127.0.0.1');
return;
}
refresh();
}

async function refresh()
{
try {
let errmsg = new YErrorMsg();
await YAPI.UpdateDeviceList(errmsg);

let module = YModule.FirstModule();
while(module) {
let line = await module.get_serialNumber();
line += '(' + (await module.get_productName()) + ')';
console.log(line);
module = module.nextModule();
}
setTimeout(refresh, 500);
} catch(e) {
console.log(e);
}
}

try {
startDemo();
} catch(e) {
console.log(e);
}

9.5. Error handling

When you implement a program which must interact with USB modules, you cannot disregard error handling. Inevitably, there will be a time when a user will have unplugged the device, either before running the software, or even while the software is running. The Yoctopuce library is designed to help you support this kind of behavior, but your code must nevertheless be conceived to interpret in the best possible way the errors indicated by the library.

The simplest way to work around the problem is the one used in the short examples provided in this chapter: before accessing a module, check that it is online with the isOnline function, and then hope that it will stay so during the fraction of a second necessary for the following code lines to run. This method is not perfect, but it can be sufficient in some cases. You must however be aware that you cannot completely exclude an error which would occur after the call to isOnline and which could crash the software. The only way to prevent this is to implement one of the two error handling techniques described below.

The method recommended by most programming languages for unpredictable error handling is the use of exceptions. By default, it is the behavior of the Yoctopuce library. If an error happens while you try to access a module, the library throws an exception. In this case, there are three possibilities:

If your code catches the exception and handles it, everything goes well.
If your program is running in debug mode, you can relatively easily determine where the problem happened and view the explanatory message linked to the exception.
Otherwise... the exception makes your program crash, bang!

As this latest situation is not the most desirable, the Yoctopuce library offers another possibility for error handling, allowing you to create a robust program without needing to catch exceptions at every line of code. You simply need to call the YAPI.DisableExceptions() function to commute the library to a mode where exceptions for all the functions are systematically replaced by specific return values, which can be tested by the caller when necessary. For each function, the name of each return value in case of error is systematically documented in the library reference. The name always follows the same logic: a get_state() method returns a Y_STATE_INVALID value, a get_currentValue method returns a Y_CURRENTVALUE_INVALID value, and so on. In any case, the returned value is of the expected type and is not a null pointer which would risk crashing your program. At worst, if you display the value without testing it, it will be outside the expected bounds for the returned value. In the case of functions which do not normally return information, the return value is YAPI_SUCCESS if everything went well, and a different error code in case of failure.

When you work without exceptions, you can obtain an error code and an error message explaining the source of the error. You can request them from the object which returned the error, calling the errType() and errMessage() methods. Their returned values contain the same information as in the exceptions when they are active.

10. Using Yocto-RS485 with PHP

PHP is, like Javascript, an atypical language when interfacing with hardware is at stakes. Nevertheless, using PHP with Yoctopuce modules provides you with the opportunity to very easily create web sites which are able to interact with their physical environment, and this is not available to every web server. This technique has a direct application in home automation: a few Yoctopuce modules, a PHP server, and you can interact with your home from anywhere on the planet, as long as you have an internet connection.

PHP is one of those languages which do not allow you to directly access the hardware layers of your computer. Therefore you need to run a virtual hub on the machine on which your modules are connected.

To start your tests with PHP, you need a PHP 5.3 (or more) server²³, preferably locally on you machine. If you wish to use the PHP server of your internet provider, it is possible, but you will probably need to configure your ADSL router for it to accept and forward TCP request on the 4444 port.

10.1. Getting ready

Go to the Yoctopuce web site and download the following items:

The PHP programming library²⁴
The VirtualHub software²⁵ for Windows, Mac OS X, or Linux, depending on your OS

Decompress the library files in a folder of your choice accessible to your web server, connect your modules, run the VirtualHub software, and you are ready to start your first tests. You do not need to install any driver.

10.2. Control of the SerialPort function

A few lines of code are enough to use a Yocto-RS485. Here is the skeleton of a PHP code snipplet to use the SerialPort function.

include('yocto_api.php');
include('yocto_serialport.php');

[...]
// Get access to your device, through the VirtualHub running locally
YAPI::RegisterHub('http://127.0.0.1:4444/',$errmsg);
[...]

// Retrieve the object used to interact with the device
$serialport = YSerialPort::FindSerialPort("RS485MK1-123456.serialPort");

// Check that the module is online to handle hot-plug
if($serialport->isOnline())
{
// Use $serialport->get_serialMode()
[...]
}

Let's look at these lines in more details.

yocto_api.php and yocto_serialport.php

These two PHP includes provides access to the functions allowing you to manage Yoctopuce modules. yocto_api.php must always be included, yocto_serialport.php is necessary to manage modules containing a serial port, such as Yocto-RS485.

YAPI::RegisterHub

The YAPI::RegisterHub function allows you to indicate on which machine the Yoctopuce modules are located, more precisely on which machine the VirtualHub software is running. In our case, the 127.0.0.1:4444 address indicates the local machine, port 4444 (the standard port used by Yoctopuce). You can very well modify this address, and enter the address of another machine on which the VirtualHub software is running.

YSerialPort::FindSerialPort

The YSerialPort::FindSerialPort function allows you to find a serial port from the serial number of the module on which it resides and from its function name. You can use logical names as well, as long as you have initialized them. Let us imagine a Yocto-RS485 module with serial number RS485MK1-123456 which you have named "MyModule", and for which you have given the serialPort function the name "MyFunction". The following five calls are strictly equivalent, as long as "MyFunction" is defined only once.

$serialport = YSerialPort::FindSerialPort("RS485MK1-123456.serialPort");
$serialport = YSerialPort::FindSerialPort("RS485MK1-123456.MyFunction");
$serialport = YSerialPort::FindSerialPort("MyModule.serialPort");
$serialport = YSerialPort::FindSerialPort("MyModule.MyFunction");
$serialport = YSerialPort::FindSerialPort("MyFunction");

YSerialPort::FindSerialPort returns an object which you can then use at will to control the serial port.

isOnline

The isOnline() method of the object returned by YSerialPort::FindSerialPort allows you to know if the corresponding module is present and in working order.

modbusWrite* and modbusRead*

The modbusWrite*() and modbusRead*() method of the object returned by yFindSerialPort provides MODBUS communication over the serial port.

A real example

Open your preferred text editor²⁶, copy the code sample below, save it with the Yoctopuce library files in a location which is accessible to you web server, then use your preferred web browser to access this page. The code is also provided in the directory Examples/Doc-GettingStarted-Yocto-RS485 of the Yoctopuce library.

In this example, you will recognize the functions explained above, but this time used with all side materials needed to make it work nicely as a small demo.

<HTML>
<HEAD>
<TITLE>Hello World</TITLE>
</HEAD>
<BODY>
<FORM method='get'>
<?php

function readModBus($serialPort, $slave, $reg)
{
if($reg >= 40001) $res = $serialPort->modbusReadRegisters($slave, $reg - 40001, 1);
else if($reg >= 30001) $res = $serialPort->modbusReadInputRegisters($slave, $reg - 30001, 1);
else if($reg >= 10001) $res = $serialPort->modbusReadInputBits($slave, $reg - 10001, 1);
else $res = $serialPort->modbusReadBits($slave, $reg - 1, 1);
return $res[0];
}

include('yocto_api.php');
include('yocto_serialport.php');

// Use explicit error handling rather than exceptions
YAPI::DisableExceptions();

$address = '127.0.0.1';

// Setup the API to use the VirtualHub on local machine,
if(YAPI::RegisterHub($address, $errmsg) != YAPI::SUCCESS) {
die("Cannot contact $address");
}

$serialPort = YSerialPort::FirstSerialPort();
if($serialPort == null)
die("No module found on $address (check USB cable)");

$slave = "";
if(isset($_GET["slave"])) $slave = $_GET["slave"];
print('Please enter the MODBUS slave address (1...255)<br>');
Print("slave:");
if($slave == '') {
Printf("<input name='slave'>");
} else {
print("<b>$slave</b><input name='slave' value='$slave' type='hidden'><br>");
$reg = "";
if(isset($_GET["reg"])) $reg = $_GET["reg"];
print("Please select a Coil No (>=1), Input Bit No (>=10001+),<br>");
print(" Input Register No (>=30001) or Register No (>=40001)<br>");
Print("No:");
if($reg == '') Printf("<input name='reg'>");
else {
print("<b>$reg</b><input name='reg' value='$reg' type='hidden'><br>");
$reg = intVal($reg);
$v = readModBus($serialPort, $slave, $reg);
print("Current value: <b><span id='value'>$v</span></b><br>");

if(($reg % 30000) < 10000) {
printf(" Enter a new value: <input name='value'><br>");
$value = '';
if(isset($_GET["value"])) $value = $_GET["value"];
if($value != '') {
if($reg >= 30001)
$serialPort->modbusWriteRegister($slave, $reg - 30001, intval($value));
else
$serialPort->modbusWriteBit($slave, $reg - 1, intval($value));
$v = readModBus($serialPort, $slave, $reg);
Print("<script>document.getElementById('value').innerHTML='$v'</SCRIPT>");
}
}
}
}
YAPI::FreeAPI();
?>
<input type='submit'>
</FORM>
</BODY>
</HTML>

10.3. Control of the module part

Each module can be controlled in a similar manner, you can find below a simple sample program displaying the main parameters of the module and enabling you to activate the localization beacon.

<HTML>
<HEAD>
<TITLE>Module Control</TITLE>
</HEAD>
<BODY>
<FORM method='get'>
<?php
include('yocto_api.php');

// Use explicit error handling rather than exceptions
YAPI::DisableExceptions();

// Setup the API to use the VirtualHub on local machine
if(YAPI::RegisterHub('http://127.0.0.1:4444/',$errmsg) != YAPI::SUCCESS) {
die("Cannot contact VirtualHub on 127.0.0.1 : ".$errmsg);
}

@$serial = $_GET['serial'];
if ($serial != '') {
// Check if a specified module is available online
$module = YModule::FindModule("$serial");
if (!$module->isOnline()) {
die("Module not connected (check serial and USB cable)");
}
} else {
// or use any connected module suitable for the demo
$module = YModule::FirstModule();
if($module) { // skip VirtualHub
$module = $module->nextModule();
}
if(is_null($module)) {
die("No module connected (check USB cable)");
} else {
$serial = $module->get_serialnumber();
}
}
Print("Module to use: <input name='serial' value='$serial'><br>");

if (isset($_GET['beacon'])) {
if ($_GET['beacon']=='ON')
$module->set_beacon(Y_BEACON_ON);
else
$module->set_beacon(Y_BEACON_OFF);
}
printf('serial: %s<br>',$module->get_serialNumber());
printf('logical name: %s<br>',$module->get_logicalName());
printf('luminosity: %s<br>',$module->get_luminosity());
print('beacon: ');
if($module->get_beacon() == Y_BEACON_ON) {
printf("<input type='radio' name='beacon' value='ON' checked>ON ");
printf("<input type='radio' name='beacon' value='OFF'>OFF<br>");
} else {
printf("<input type='radio' name='beacon' value='ON'>ON ");
printf("<input type='radio' name='beacon' value='OFF' checked>OFF<br>");
}
printf('upTime: %s sec<br>',intVal($module->get_upTime()/1000));
printf('USB current: %smA<br>',$module->get_usbCurrent());
printf('logs:<br><pre>%s</pre>',$module->get_lastLogs());
YAPI::FreeAPI();
?>
<input type='submit' value='refresh'>
</FORM>
</BODY>
</HTML>

Changing the module settings

<HTML>
<HEAD>
<TITLE>save settings</TITLE>
<BODY>
<FORM method='get'>
<?php
include('yocto_api.php');

// Use explicit error handling rather than exceptions
YAPI::DisableExceptions();

// Setup the API to use the VirtualHub on local machine
if(YAPI::RegisterHub('http://127.0.0.1:4444/',$errmsg) != YAPI::SUCCESS) {
die("Cannot contact VirtualHub on 127.0.0.1");
}

@$serial = $_GET['serial'];
if ($serial != '') {
// Check if a specified module is available online
$module = YModule::FindModule("$serial");
if (!$module->isOnline()) {
die("Module not connected (check serial and USB cable)");
}
} else {
// or use any connected module suitable for the demo
$module = YModule::FirstModule();
if($module) { // skip VirtualHub
$module = $module->nextModule();
}
if(is_null($module)) {
die("No module connected (check USB cable)");
} else {
$serial = $module->get_serialnumber();
}
}
Print("Module to use: <input name='serial' value='$serial'><br>");

if (isset($_GET['newname'])){
$newname = $_GET['newname'];
if (!yCheckLogicalName($newname))
die('Invalid name');
$module->set_logicalName($newname);
$module->saveToFlash();
}
printf("Current name: %s<br>", $module->get_logicalName());
print("New name: <input name='newname' value='' maxlength=19><br>");
YAPI::FreeAPI();
?>
<input type='submit'>
</FORM>
</BODY>
</HTML>

Listing the modules

Obtaining the list of the connected modules is performed with the yFirstModule() function which returns the first module found. Then, you only need to call the nextModule() function of this object to find the following modules, and this as long as the returned value is not NULL. Below a short example listing the connected modules.

<HTML>
<HEAD>
<TITLE>inventory</TITLE>
</HEAD>
<BODY>
<H1>Device list</H1>
<TT>
<?php
include('yocto_api.php');
YAPI::RegisterHub("http://127.0.0.1:4444/");
$module = YModule::FirstModule();
while (!is_null($module)) {
printf("%s (%s)<br>", $module->get_serialNumber(),
$module->get_productName());
$module=$module->nextModule();
}
YAPI::FreeAPI();
?>
</TT>
</BODY>
</HTML>

10.4. HTTP callback API and NAT filters

The PHP library is able to work in a specific mode called HTTP callback Yocto-API. With this mode, you can control Yoctopuce devices installed behind a NAT filter, such as a DSL router for example, and this without needing to open a port. The typical application is to control Yoctopuce devices, located on a private network, from a public web site.

The NAT filter: advantages and disadvantages

A DSL router which translates network addresses (NAT) works somewhat like a private phone switchboard (a PBX): internal extensions can call each other and call the outside; but seen from the outside, there is only one official phone number, that of the switchboard itself. You cannot reach the internal extensions from the outside.

Typical DSL configuration: LAN machines are isolated from the outside by the DSL router

Transposed to the network, we have the following: appliances connected to your home automation network can communicate with one another using a local IP address (of the 192.168.xxx.yyy type), and contact Internet servers through their public address. However, seen from the outside, you have only one official IP address, assigned to the DSL router only, and you cannot reach your network appliances directly from the outside. It is rather restrictive, but it is a relatively efficient protection against intrusions.

Responses from request from LAN machines are routed.

But requests from the outside are blocked.

Seeing Internet without being seen provides an enormous security advantage. However, this signifies that you cannot, a priori, set up your own web server at home to control a home automation installation from the outside. A solution to this problem, advised by numerous home automation system dealers, consists in providing outside visibility to your home automation server itself, by adding a routing rule in the NAT configuration of the DSL router. The issue of this solution is that it exposes the home automation server to external attacks.

The HTTP callback API solves this issue without having to modify the DSL router configuration. The module control script is located on an external site, and it is the VirtualHub which is in charge of calling it a regular intervals.

The HTTP callback API uses the VirtualHub which initiates the requests.

Configuration

The callback API thus uses the VirtualHub as a gateway. All the communications are initiated by the VirtualHub. They are thus outgoing communications and therefore perfectly authorized by the DSL router.

You must configure the VirtualHub so that it calls the PHP script on a regular basis. To do so:

Launch a VirtualHub
Access its interface, usually 127.0.0.1:4444
Click on the configure button of the line corresponding to the VirtualHub itself
Click on the edit button of the Outgoing callbacks section

Click on the "configure" button on the first line

Click on the "edit" button of the "Outgoing callbacks" section

And select "Yocto-API callback".

You then only need to define the URL of the PHP script and, if need be, the user name and password to access this URL. Supported authentication methods are basic and digest. The second method is safer than the first one because it does not allow transfer of the password on the network.

Usage

From the programmer standpoint, the only difference is at the level of the yRegisterHub function call. Instead of using an IP address, you must use the callback string (or http://callback which is equivalent).

include("yocto_api.php");
yRegisterHub("callback");

The remainder of the code stays strictly identical. On the VirtualHub interface, at the bottom of the configuration window for the HTTP callback API , there is a button allowing you to test the call to the PHP script.

Be aware that the PHP script controlling the modules remotely through the HTTP callback API can be called only by the VirtualHub. Indeed, it requires the information posted by the VirtualHub to function. To code a web site which controls Yoctopuce modules interactively, you must create a user interface which stores in a file or in a database the actions to be performed on the Yoctopuce modules. These actions are then read and run by the control script.

Common issues

For the HTTP callback API to work, the PHP option allow_url_fopen must be set. Some web site hosts do not set it by default. The problem then manifests itself with the following error:

error: URL file-access is disabled in the server configuration

To set this option, you must create, in the repertory where the control PHP script is located, an .htaccess file containing the following line:
php_flag "allow_url_fopen" "On"
Depending on the security policies of the host, it is sometimes impossible to authorize this option at the root of the web site, or even to install PHP scripts receiving data from a POST HTTP. In this case, place the PHP script in a subdirectory.

Limitations

This method that allows you to go through NAT filters cheaply has nevertheless a price. Communications being initiated by the VirtualHub at a more or less regular interval, reaction time to an event is clearly longer than if the Yoctopuce modules were driven directly. You can configure the reaction time in the specific window of the VirtualHub, but it is at least of a few seconds in the best case.

The HTTP callback Yocto-API mode is currently available in PHP, EcmaScript (Node.JS) and Java only.

10.5. Error handling

If your code catches the exception and handles it, everything goes well.
If your program is running in debug mode, you can relatively easily determine where the problem happened and view the explanatory message linked to the exception.
Otherwise... the exception makes your program crash, bang!

11. Using Yocto-RS485 with C++

C++ is not the simplest language to master. However, if you take care to limit yourself to its essential functionalities, this language can very well be used for short programs quickly coded, and it has the advantage of being easily ported from one operating system to another. Under Windows, all the examples and the project models are tested with Microsoft Visual Studio 2010 Express, freely available on the Microsoft web site²⁷. Under Mac OS X, all the examples and project models are tested with XCode 4, available on the App Store. Moreover, under Max OS X and under Linux, you can compile the examples using a command line with GCC using the provided GNUmakefile. In the same manner under Windows, a Makefile allows you to compile examples using a command line, fully knowing the compilation and linking arguments.

Yoctopuce C++ libraries²⁸ are integrally provided as source files. A section of the low-level library is written in pure C, but you should not need to interact directly with it: everything was done to ensure the simplest possible interaction from C++. The library is naturally also available as binary files, so that you can link it directly if you prefer.

You will soon notice that the C++ API defines many functions which return objects. You do not need to deallocate these objects yourself, the API does it automatically at the end of the application.

In order to keep them simple, all the examples provided in this documentation are console applications. Naturally, the libraries function in a strictly identical manner if you integrate them in an application with a graphical interface. You will find in the last section of this chapter all the information needed to create a wholly new project linked with the Yoctopuce libraries.

11.1. Control of the SerialPort function

A few lines of code are enough to use a Yocto-RS485. Here is the skeleton of a C++ code snipplet to use the SerialPort function.

#include "yocto_api.h"
#include "yocto_serialport.h"

[...]
// Enable detection of USB devices
String errmsg;
YAPI::RegisterHub("usb", errmsg);
[...]

// Retrieve the object used to interact with the device
YSerialPort *serialport;
serialport = YSerialPort::FindSerialPort("RS485MK1-123456.serialPort");

// Hot-plug is easy: just check that the device is online
if(serialport->isOnline())
{
// Use serialport->get_serialMode()
[...]
}

Let's look at these lines in more details.

yocto_api.h et yocto_serialport.h

These two include files provide access to the functions allowing you to manage Yoctopuce modules. yocto_api.h must always be used, yocto_serialport.h is necessary to manage modules containing a serial port, such as Yocto-RS485.

YAPI::RegisterHub

The YAPI::RegisterHub function initializes the Yoctopuce API and indicates where the modules should be looked for. When used with the parameter "usb", it will use the modules locally connected to the computer running the library. If the initialization does not succeed, this function returns a value different from YAPI_SUCCESS and errmsg contains the error message.

YSerialPort::FindSerialPort

YSerialPort *serialport = YSerialPort::FindSerialPort("RS485MK1-123456.serialPort");
YSerialPort *serialport = YSerialPort::FindSerialPort("RS485MK1-123456.MyFunction");
YSerialPort *serialport = YSerialPort::FindSerialPort("MyModule.serialPort");
YSerialPort *serialport = YSerialPort::FindSerialPort("MyModule.MyFunction");
YSerialPort *serialport = YSerialPort::FindSerialPort("MyFunction");

YSerialPort::FindSerialPort returns an object which you can then use at will to control the serial port.

isOnline

The isOnline() method of the object returned by YSerialPort::FindSerialPort allows you to know if the corresponding module is present and in working order.

modbusWrite* and modbusRead*

The modbusWrite*() and modbusRead*() method of the object returned by yFindSerialPort provides MODBUS communication over the serial port.

A real example

Launch your C++ environment and open the corresponding sample project provided in the directory Examples/Doc-GettingStarted-Yocto-RS485 of the Yoctopuce library. If you prefer to work with your favorite text editor, open the file main.cpp, and type make to build the example when you are done.

In this example, you will recognize the functions explained above, but this time used with all side materials needed to make it work nicely as a small demo.

#include "yocto_api.h"
#include "yocto_serialport.h"
#include <iostream>
#include <stdlib.h>

using namespace std;

int main(int argc, const char * argv[])
{
string errmsg;

if (YAPI::RegisterHub("usb", errmsg) != YAPI::SUCCESS) {
cerr << "RegisterHub error : " << errmsg << endl;
return 1;
}

YSerialPort *serialPort;
if (argc > 1 && string(argv[1]) != "any") {
serialPort = YSerialPort::FindSerialPort(string(argv[1]));
} else {
serialPort = YSerialPort::FirstSerialPort();
if (serialPort == NULL) {
cerr << "No module connected (check USB cable)" << endl;
return 1;
}
}
if (!serialPort->isOnline()) {
cout << "Module not connected (check identification and USB cable)" << endl;
return 1;
}

int slave, reg, val;
string cmd;
do {
cout << "Please enter the MODBUS slave address (1...255)" << endl;
cout << "Slave: ";
cin >> slave;
} while(slave < 1 || slave > 255);
do {
cout << "Please select a Coil No (>=1), Input Bit No (>=10001+)," << endl;
cout << " Input Register No (>=30001) or Register No (>=40001)" << endl;
cout << "No: " ;
cin >> reg;
} while(reg < 1 || reg >= 50000 || (reg % 10000) == 0);
while(serialPort->isOnline()) {
if(reg >= 40001) {
val = serialPort->modbusReadRegisters(slave, reg - 40001, 1)[0];
} else if(reg >= 30001) {
val = serialPort->modbusReadInputRegisters(slave, reg - 30001, 1)[0];
} else if(reg >= 10001) {
val = serialPort->modbusReadInputBits(slave, reg - 10001, 1)[0];
} else {
val = serialPort->modbusReadBits(slave, reg - 1, 1)[0];
}
cout << "Current value: " << val << endl;
cout << "Press R to read again, Q to quit";
if((reg % 30000) < 10000) {
cout << " or enter a new value";
}
cout << ": " << endl;
cin >> cmd;
if(cmd == "q" || cmd == "Q") break;
if (cmd != "r" && cmd != "R" && (reg % 30000) < 10000) {
val = atoi(cmd.c_str());
if(reg >= 30001) {
serialPort->modbusWriteRegister(slave, reg - 30001, val);
} else {
serialPort->modbusWriteBit(slave, reg - 1, val);
}
}
}
YAPI::FreeAPI();
return 0;
}

11.2. Control of the module part

Each module can be controlled in a similar manner, you can find below a simple sample program displaying the main parameters of the module and enabling you to activate the localization beacon.

#include <iostream>
#include <stdlib.h>

#include "yocto_api.h"

using namespace std;

static void usage(const char *exe)
{
cout << "usage: " << exe << " <serial or logical name> [ON/OFF]" << endl;
exit(1);
}

int main(int argc, const char * argv[])
{
string errmsg;

// Setup the API to use local USB devices
if(YAPI::RegisterHub("usb", errmsg) != YAPI::SUCCESS) {
cerr << "RegisterHub error: " << errmsg << endl;
return 1;
}

if(argc < 2)
usage(argv[0]);

YModule *module = YModule::FindModule(argv[1]); // use serial or logical name

if (module->isOnline()) {
if (argc > 2) {
if (string(argv[2]) == "ON")
module->set_beacon(Y_BEACON_ON);
else
module->set_beacon(Y_BEACON_OFF);
}
cout << "serial: " << module->get_serialNumber() << endl;
cout << "logical name: " << module->get_logicalName() << endl;
cout << "luminosity: " << module->get_luminosity() << endl;
cout << "beacon: ";
if (module->get_beacon() == Y_BEACON_ON)
cout << "ON" << endl;
else
cout << "OFF" << endl;
cout << "upTime: " << module->get_upTime() / 1000 << " sec" << endl;
cout << "USB current: " << module->get_usbCurrent() << " mA" << endl;
cout << "Logs:" << endl << module->get_lastLogs() << endl;
} else {
cout << argv[1] << " not connected (check identification and USB cable)"
<< endl;
}
YAPI::FreeAPI();
return 0;
}

Changing the module settings

#include <iostream>
#include <stdlib.h>

#include "yocto_api.h"

using namespace std;

static void usage(const char *exe)
{
cerr << "usage: " << exe << " <serial> <newLogicalName>" << endl;
exit(1);
}

int main(int argc, const char * argv[])
{
string errmsg;

// Setup the API to use local USB devices
if(YAPI::RegisterHub("usb", errmsg) != YAPI::SUCCESS) {
cerr << "RegisterHub error: " << errmsg << endl;
return 1;
}

if(argc < 2)
usage(argv[0]);

YModule *module = YModule::FindModule(argv[1]); // use serial or logical name

if (module->isOnline()) {
if (argc >= 3) {
string newname = argv[2];
if (!yCheckLogicalName(newname)) {
cerr << "Invalid name (" << newname << ")" << endl;
usage(argv[0]);
}
module->set_logicalName(newname);
module->saveToFlash();
}
cout << "Current name: " << module->get_logicalName() << endl;
} else {
cout << argv[1] << " not connected (check identification and USB cable)"
<< endl;
}
YAPI::FreeAPI();
return 0;
}

Listing the modules

#include <iostream>

#include "yocto_api.h"

using namespace std;

int main(int argc, const char * argv[])
{
string errmsg;

// Setup the API to use local USB devices
if(YAPI::RegisterHub("usb", errmsg) != YAPI::SUCCESS) {
cerr << "RegisterHub error: " << errmsg << endl;
return 1;
}

cout << "Device list: " << endl;

YModule *module = YModule::FirstModule();
while (module != NULL) {
cout << module->get_serialNumber() << " ";
cout << module->get_productName() << endl;
module = module->nextModule();
}
YAPI::FreeAPI();
return 0;
}

11.3. Error handling

If your code catches the exception and handles it, everything goes well.
If your program is running in debug mode, you can relatively easily determine where the problem happened and view the explanatory message linked to the exception.
Otherwise... the exception makes your program crash, bang!

11.4. Integration variants for the C++ Yoctopuce library

Depending on your needs and on your preferences, you can integrate the library into your projects in several distinct manners. This section explains how to implement the different options.

Integration in source format (recommended)

Integrating all the sources of the library into your projects has several advantages:

It guaranties the respect of the compilation conventions of your project (32/64 bits, inclusion of debugging symbols, unicode or ASCII characters, etc.);
It facilitates debugging if you are looking for the cause of a problem linked to the Yoctopuce library;
It reduces the dependencies on third party components, for example in the case where you would need to recompile this project for another architecture in many years;
It does not require the installation of a dynamic library specific to Yoctopuce on the final system, everything is in the executable.

To integrate the source code, the easiest way is to simply include the Sources directory of your Yoctopuce library into your IncludePath, and to add all the files of this directory (including the sub-directory yapi) to your project.

For your project to build correctly, you need to link with your project the prerequisite system libraries, that is:

For Windows: the libraries are added automatically
For Mac OS X: IOKit.framework and CoreFoundation.framework
For Linux: libm, libpthread, libusb1.0, and libstdc++

Integration as a static library

With the integration of the Yoctopuce library as a static library, you do not need to install a dynamic library specific to Yoctopuce, everything is in the executable.

To use the static library, you must first compile it using the shell script build.sh on UNIX, or build.bat on Windows. This script, located in the root directory of the library, detects the OS and recompiles all the corresponding libraries as well as the examples.

Then, to integrate the static Yoctopuce library to your project, you must include the Sources directory of the Yoctopuce library into your IncludePath, and add the sub-directory Binaries/... corresponding to your operating system into your libPath.

Finally, for you project to build correctly, you need to link with your project the Yoctopuce library and the prerequisite system libraries:

For Windows: yocto-static.lib
For Mac OS X: libyocto-static.a, IOKit.framework, and CoreFoundation.framework
For Linux: libyocto-static.a, libm, libpthread, libusb1.0, and libstdc++.

Note, under Linux, if you wish to compile in command line with GCC, it is generally advisable to link system libraries as dynamic libraries, rather than as static ones. To mix static and dynamic libraries on the same command line, you must pass the following arguments:

gcc (...) -Wl,-Bstatic -lyocto-static -Wl,-Bdynamic -lm -lpthread -lusb-1.0 -lstdc++

Integration as a dynamic library

Integration of the Yoctopuce library as a dynamic library allows you to produce an executable smaller than with the two previous methods, and to possibly update this library, if a patch reveals itself necessary, without needing to recompile the source code of the application. On the other hand, it is an integration mode which systematically requires you to copy the dynamic library on the target machine where the application will run (yocto.dll for Windows, libyocto.so.1.0.1 for Mac OS X and Linux).

To use the dynamic library, you must first compile it using the shell script build.sh on UNIX, or build.bat on Windows. This script, located in the root directory of the library, detects the OS and recompiles all the corresponding libraries as well as the examples.

Then, To integrate the dynamic Yoctopuce library to your project, you must include the Sources directory of the Yoctopuce library into your IncludePath, and add the sub-directory Binaries/... corresponding to your operating system into your LibPath.

Finally, for you project to build correctly, you need to link with your project the dynamic Yoctopuce library and the prerequisite system libraries:

For Windows: yocto.lib
For Mac OS X: libyocto, IOKit.framework, and CoreFoundation.framework
For Linux: libyocto, libm, libpthread, libusb1.0, and libstdc++.

With GCC, the command line to compile is simply:

gcc (...) -lyocto -lm -lpthread -lusb-1.0 -lstdc++

12. Using Yocto-RS485 with Objective-C

Objective-C is language of choice for programming on Mac OS X, due to its integration with the Cocoa framework. In order to use the Objective-C library, you need XCode version 4.2 (earlier versions will not work), available freely when you run Lion. If you are still under Snow Leopard, you need to be registered as Apple developer to be able to download XCode 4.2. The Yoctopuce library is ARC compatible. You can therefore implement your projects either using the traditional retain / release method, or using the Automatic Reference Counting.

Yoctopuce Objective-C libraries²⁹ are integrally provided as source files. A section of the low-level library is written in pure C, but you should not need to interact directly with it: everything was done to ensure the simplest possible interaction from Objective-C.

You will soon notice that the Objective-C API defines many functions which return objects. You do not need to deallocate these objects yourself, the API does it automatically at the end of the application.

In order to keep them simple, all the examples provided in this documentation are console applications. Naturally, the libraries function in a strictly identical manner if you integrate them in an application with a graphical interface. You can find on Yoctopuce blog a detailed example³⁰ with video shots showing how to integrate the library into your projects.

12.1. Control of the SerialPort function

A few lines of code are enough to use a Yocto-RS485. Here is the skeleton of a Objective-C code snipplet to use the SerialPort function.

#import "yocto_api.h"
#import "yocto_serialport.h"

...
NSError *error;
[YAPI RegisterHub:@"usb": &error]
...
// On récupère l'objet représentant le module (ici connecté en local sur USB)
serialport = [YSerialPort FindSerialPort:@"RS485MK1-123456.serialPort"];

// Pour gérer le hot-plug, on vérifie que le module est là
if([serialport isOnline])
{
// Utiliser [serialport get_serialMode]
...
}

Let's look at these lines in more details.

yocto_api.h and yocto_serialport.h

These two import files provide access to the functions allowing you to manage Yoctopuce modules. yocto_api.h must always be used, yocto_serialport.h is necessary to manage modules containing a serial port, such as Yocto-RS485.

[YAPI RegisterHub]

The [YAPI RegisterHub] function initializes the Yoctopuce API and indicates where the modules should be looked for. When used with the parameter @"usb", it will use the modules locally connected to the computer running the library. If the initialization does not succeed, this function returns a value different from YAPI_SUCCESS and errmsg contains the error message.

[SerialPort FindSerialPort]

The [SerialPort FindSerialPort] function allows you to find a serial port from the serial number of the module on which it resides and from its function name. You can use logical names as well, as long as you have initialized them. Let us imagine a Yocto-RS485 module with serial number RS485MK1-123456 which you have named "MyModule", and for which you have given the serialPort function the name "MyFunction". The following five calls are strictly equivalent, as long as "MyFunction" is defined only once.

YSerialPort *serialport = [SerialPort FindSerialPort:@"RS485MK1-123456.serialPort"];
YSerialPort *serialport = [SerialPort FindSerialPort:@"RS485MK1-123456.MyFunction"];
YSerialPort *serialport = [SerialPort FindSerialPort:@"MyModule.serialPort"];
YSerialPort *serialport = [SerialPort FindSerialPort:@"MyModule.MyFunction"];
YSerialPort *serialport = [SerialPort FindSerialPort:@"MyFunction"];

[SerialPort FindSerialPort] returns an object which you can then use at will to control the serial port.

isOnline

The isOnline method of the object returned by [SerialPort FindSerialPort] allows you to know if the corresponding module is present and in working order.

modbusWrite* and modbusRead*

The modbusWrite*() and modbusRead*() method of the object returned by YFindSerialPort.FindSerialPort provides MODBUS communication overs the serial port.

A real example

Launch Xcode 4.2 and open the corresponding sample project provided in the directory Examples/Doc-GettingStarted-Yocto-RS485 of the Yoctopuce library.

In this example, you will recognize the functions explained above, but this time used with all side materials needed to make it work nicely as a small demo.

#import <Foundation/Foundation.h>
#import "yocto_api.h"
#import "yocto_serialport.h"

int main(int argc, const char * argv[])
{
NSError *error;
char cmd[50] = {0};

@autoreleasepool {
// Setup the API to use local USB devices
if([YAPI RegisterHub:@"usb": &error] != YAPI_SUCCESS) {
NSLog(@"RegisterHub error: %@", [error localizedDescription]);
return 1;
}

YSerialPort *serialPort;
if (argc > 1) {
NSString *target = [NSString stringWithUTF8String:argv[1]];
serialPort = [YSerialPort FindSerialPort:target];
} else {
serialPort = [YSerialPort FirstSerialPort];
if (serialPort == NULL) {
NSLog(@"No module connected (check USB cable)");
return 1;
}
}

int slave, reg, val;
do {
NSLog(@"Please enter the MODBUS slave address (1...255)");
NSLog(@"Slave: ");
fgets(cmd, sizeof(cmd), stdin);
slave = atoi(cmd);
} while(slave < 1 || slave > 255);
do {
NSLog(@"Please select a Coil No (>=1), Input Bit No (>=10001+),");
NSLog(@" Register No (>=30001) or Input Register No (>=40001)");
NSLog(@"No: ");
fgets(cmd, sizeof(cmd), stdin);
reg = atoi(cmd);
} while(reg < 1 || reg >= 50000 || (reg % 10000) == 0);
while(true) {
if(reg >= 40001) {
val = (int)[[[serialPort modbusReadRegisters:slave :reg - 40001 :1] objectAtIndex:0]
integerValue];
} else if(reg >= 30001) {
val = (int)[[[serialPort modbusReadInputRegisters:slave :reg - 30001 :1] objectAtIndex:0]
integerValue];
} else if(reg >= 10001) {
val = (int)[[[serialPort modbusReadInputBits:slave :reg - 10001 :1] objectAtIndex:0]
integerValue];
} else {
val = (int)[[[serialPort modbusReadBits:slave :reg - 1 :1] objectAtIndex:0] integerValue];
}
NSLog(@"Current value: %d" , val );
NSLog(@"Press R to read again, Q to quit");
if((reg % 30000) < 10000) {
NSLog(@" or enter a new value");
}
NSLog(@": ");
fgets(cmd, sizeof(cmd), stdin);
if(cmd[0] == 'q' || cmd[0] == 'Q') break;
if (cmd[0] != 'r' && cmd[0] != 'R' && (reg % 30000) < 10000) {
val = atoi(cmd);
if(reg >= 30001) {
[serialPort modbusWriteRegister:slave :reg - 30001 :val];
} else {
[serialPort modbusWriteBit:slave :reg - 1 :val];
}
}
}
[YAPI FreeAPI];
}
return 0;
}

12.2. Control of the module part

Each module can be controlled in a similar manner, you can find below a simple sample program displaying the main parameters of the module and enabling you to activate the localization beacon.

#import <Foundation/Foundation.h>
#import "yocto_api.h"

static void usage(const char *exe)
{
NSLog(@"usage: %s <serial or logical name> [ON/OFF]\n", exe);
exit(1);
}

int main (int argc, const char * argv[])
{
NSError *error;

@autoreleasepool {
// Setup the API to use local USB devices
if([YAPI RegisterHub:@"usb": &error] != YAPI_SUCCESS) {
NSLog(@"RegisterHub error: %@", [error localizedDescription]);
return 1;
}
if(argc < 2)
usage(argv[0]);
NSString *serial_or_name = [NSString stringWithUTF8String:argv[1]];
// use serial or logical name
YModule *module = [YModule FindModule:serial_or_name];
if ([module isOnline]) {
if (argc > 2) {
if (strcmp(argv[2], "ON") == 0)
[module setBeacon:Y_BEACON_ON];
else
[module setBeacon:Y_BEACON_OFF];
}
NSLog(@"serial: %@\n", [module serialNumber]);
NSLog(@"logical name: %@\n", [module logicalName]);
NSLog(@"luminosity: %d\n", [module luminosity]);
NSLog(@"beacon: ");
if ([module beacon] == Y_BEACON_ON)
NSLog(@"ON\n");
else
NSLog(@"OFF\n");
NSLog(@"upTime: %ld sec\n", [module upTime] / 1000);
NSLog(@"USB current: %d mA\n", [module usbCurrent]);
NSLog(@"logs: %@\n", [module get_lastLogs]);
} else {
NSLog(@"%@ not connected (check identification and USB cable)\n",
serial_or_name);
}
[YAPI FreeAPI];
}
return 0;
}

Each property xxx of the module can be read thanks to a method of type get_xxxx, and properties which are not read-only can be modified with the help of the set_xxx: method. For more details regarding the used functions, refer to the API chapters.

Changing the module settings

When you want to modify the settings of a module, you only need to call the corresponding set_xxx: function. However, this modification is performed only in the random access memory (RAM) of the module: if the module is restarted, the modifications are lost. To memorize them persistently, it is necessary to ask the module to save its current configuration in its permanent memory. To do so, use the saveToFlash method. Inversely, it is possible to force the module to forget its current settings by using the revertFromFlash method. The short example below allows you to modify the logical name of a module.

#import <Foundation/Foundation.h>
#import "yocto_api.h"

static void usage(const char *exe)
{
NSLog(@"usage: %s <serial> <newLogicalName>\n", exe);
exit(1);
}

int main (int argc, const char * argv[])
{
NSError *error;

@autoreleasepool {
// Setup the API to use local USB devices
if([YAPI RegisterHub:@"usb" :&error] != YAPI_SUCCESS) {
NSLog(@"RegisterHub error: %@", [error localizedDescription]);
return 1;
}

if(argc < 2)
usage(argv[0]);

NSString *serial_or_name = [NSString stringWithUTF8String:argv[1]];
// use serial or logical name
YModule *module = [YModule FindModule:serial_or_name];

if (module.isOnline) {
if (argc >= 3) {
NSString *newname = [NSString stringWithUTF8String:argv[2]];
if (![YAPI CheckLogicalName:newname]) {
NSLog(@"Invalid name (%@)\n", newname);
usage(argv[0]);
}
module.logicalName = newname;
[module saveToFlash];
}
NSLog(@"Current name: %@\n", module.logicalName);
} else {
NSLog(@"%@ not connected (check identification and USB cable)\n",
serial_or_name);
}
[YAPI FreeAPI];
}
return 0;
}

Warning: the number of write cycles of the nonvolatile memory of the module is limited. When this limit is reached, nothing guaranties that the saving process is performed correctly. This limit, linked to the technology employed by the module micro-processor, is located at about 100000 cycles. In short, you can use the saveToFlash function only 100000 times in the life of the module. Make sure you do not call this function within a loop.

Listing the modules

#import <Foundation/Foundation.h>
#import "yocto_api.h"

int main (int argc, const char * argv[])
{
NSError *error;

@autoreleasepool {
// Setup the API to use local USB devices
if([YAPI RegisterHub:@"usb" :&error] != YAPI_SUCCESS) {
NSLog(@"RegisterHub error: %@\n", [error localizedDescription]);
return 1;
}

NSLog(@"Device list:\n");

YModule *module = [YModule FirstModule];
while (module != nil) {
NSLog(@"%@ %@", module.serialNumber, module.productName);
module = [module nextModule];
}
[YAPI FreeAPI];
}
return 0;
}

12.3. Error handling

If your code catches the exception and handles it, everything goes well.
If your program is running in debug mode, you can relatively easily determine where the problem happened and view the explanatory message linked to the exception.
Otherwise... the exception makes your program crash, bang!

13. Using Yocto-RS485 with Visual Basic .NET

VisualBasic has long been the most favored entrance path to the Microsoft world. Therefore, we had to provide our library for this language, even if the new trend is shifting to C#. All the examples and the project models are tested with Microsoft VisualBasic 2010 Express, freely available on the Microsoft web site³¹.

13.1. Installation

Download the Visual Basic Yoctopuce library from the Yoctopuce web site³². There is no setup program, simply copy the content of the zip file into the directory of your choice. You mostly need the content of the Sources directory. The other directories contain the documentation and a few sample programs. All sample projects are Visual Basic 2010, projects, if you are using a previous version, you may have to recreate the projects structure from scratch.

13.2. Using the Yoctopuce API in a Visual Basic project

The Visual Basic.NET Yoctopuce library is composed of a DLL and of source files in Visual Basic. The DLL is not a .NET DLL, but a classic DLL, written in C, which manages the low level communications with the modules³³. The source files in Visual Basic manage the high level part of the API. Therefore, your need both this DLL and the .vb files of the sources directory to create a project managing Yoctopuce modules.

Configuring a Visual Basic project

The following indications are provided for Visual Studio Express 2010, but the process is similar for other versions. Start by creating your project. Then, on the Solution Explorer panel, right click on your project, and select "Add" and then "Add an existing item".

A file selection window opens. Select the yocto_api.vb file and the files corresponding to the functions of the Yoctopuce modules that your project is going to manage. If in doubt, select all the files.

You then have the choice between simply adding these files to your project, or to add them as links (the Add button is in fact a scroll-down menu). In the first case, Visual Studio copies the selected files into your project. In the second case, Visual Studio simply keeps a link on the original files. We recommend you to use links, which makes updates of the library much easier.

Then add in the same manner the yapi.dll DLL, located in the Sources/dll directory³⁴. Then, from the Solution Explorer window, right click on the DLL, select Properties and in the Properties panel, set the Copy to output folder to always. You are now ready to use your Yoctopuce modules from Visual Studio.

13.3. Control of the SerialPort function

A few lines of code are enough to use a Yocto-RS485. Here is the skeleton of a Visual Basic code snipplet to use the SerialPort function.

[...]
' Enable detection of USB devices
Dim errmsg As String errmsg
YAPI.RegisterHub("usb", errmsg)
[...]

' Retrieve the object used to interact with the device
Dim serialport As YSerialPort
serialport = YSerialPort.FindSerialPort("RS485MK1-123456.serialPort")

' Hot-plug is easy: just check that the device is online
If (serialport.isOnline()) Then
' Use serialport.get_serialMode()
[...]
End If

[...]

Let's look at these lines in more details.

YAPI.RegisterHub

The YAPI.RegisterHub function initializes the Yoctopuce API and indicates where the modules should be looked for. When used with the parameter "usb", it will use the modules locally connected to the computer running the library. If the initialization does not succeed, this function returns a value different from YAPI_SUCCESS and errmsg contains the error message.

YSerialPort.FindSerialPort

The YSerialPort.FindSerialPort function allows you to find a serial port from the serial number of the module on which it resides and from its function name. You can use logical names as well, as long as you have initialized them. Let us imagine a Yocto-RS485 module with serial number RS485MK1-123456 which you have named "MyModule", and for which you have given the serialPort function the name "MyFunction". The following five calls are strictly equivalent, as long as "MyFunction" is defined only once.

serialport = YSerialPort.FindSerialPort("RS485MK1-123456.serialPort")
serialport = YSerialPort.FindSerialPort("RS485MK1-123456.MyFunction")
serialport = YSerialPort.FindSerialPort("MyModule.serialPort")
serialport = YSerialPort.FindSerialPort("MyModule.MyFunction")
serialport = YSerialPort.FindSerialPort("MyFunction")

YSerialPort.FindSerialPort returns an object which you can then use at will to control the serial port.

isOnline

The isOnline() method of the object returned by YSerialPort.FindSerialPort allows you to know if the corresponding module is present and in working order.

modbusWrite* and modbusRead*

The modbusWrite*() and modbusRead*() method of the object returned by yFindSerialPort provides MODBUS communication over the serial port.

A real example

Launch Microsoft VisualBasic and open the corresponding sample project provided in the directory Examples/Doc-GettingStarted-Yocto-RS485 of the Yoctopuce library.

In this example, you will recognize the functions explained above, but this time used with all side materials needed to make it work nicely as a small demo.

Imports System.IO
Imports System.Environment

Module Module1

Sub Main()

Dim argv() As String = System.Environment.GetCommandLineArgs()
Dim serialPort As YSerialPort
Dim errmsg = ""
Dim cmd As String
Dim slave, reg, val As Integer

REM Setup the API to use local USB devices. You can
REM use an IP address instead of 'usb' if the device
REM is connected to a network.

If (YAPI.RegisterHub("usb", errmsg) <> YAPI.SUCCESS) Then
Console.WriteLine("yInitAPI failed: " + errmsg)
End
End If

If (argv.Length > 1 And argv(1) <> "any") Then
serialPort = YSerialPort.FindSerialPort(argv(1))
Else
serialPort = YSerialPort.FirstSerialPort()
If serialPort Is Nothing Then
Console.WriteLine("No module connected (check USB cable)")
End
End If
End If

Console.WriteLine("Please enter the MODBUS slave address (1...255)")
Console.WriteLine("Slave: ")
slave = Convert.ToInt32(Console.ReadLine())

Console.WriteLine("Please select a Coil No (>=1), Input Bit No (>=10001+),")
Console.WriteLine(" Input Register No (>=30001) or Register No (>=40001)")
Console.WriteLine("No: ")
reg = Convert.ToInt32(Console.ReadLine())
While (serialPort.isOnline())
If reg >= 40001 Then
val = serialPort.modbusReadRegisters(slave, reg - 40001, 1)(0)
ElseIf (reg >= 30001) Then
val = serialPort.modbusReadInputRegisters(slave, reg - 30001, 1)(0)
ElseIf (reg >= 10001) Then
val = serialPort.modbusReadInputBits(slave, reg - 10001, 1)(0)
Else
val = serialPort.modbusReadBits(slave, reg - 1, 1)(0)
End If
Console.WriteLine("Current value: " + Convert.ToString(val))
Console.WriteLine("Press ENTER to read again, Q to quit")
If ((reg Mod 30000) < 10000) Then Console.WriteLine(" or enter a new value")

cmd = Console.ReadLine()
If cmd = "q" Or cmd = "Q" Then End

If (cmd <> "" And (reg Mod 30000) < 10000) Then
val = Convert.ToInt32(cmd)
If reg >= 30001 Then
serialPort.modbusWriteRegister(slave, reg - 30001, val)
Else
serialPort.modbusWriteBit(slave, reg - 1, val)
End If
End If
End While
YAPI.FreeAPI()
End Sub

End Module

13.4. Control of the module part

Each module can be controlled in a similar manner, you can find below a simple sample program displaying the main parameters of the module and enabling you to activate the localization beacon.

Imports System.IO
Imports System.Environment

Module Module1

Sub usage()
Console.WriteLine("usage: demo <serial or logical name> [ON/OFF]")
End
End Sub

Sub Main()
Dim argv() As String = System.Environment.GetCommandLineArgs()
Dim errmsg As String = ""
Dim m As ymodule

If (YAPI.RegisterHub("usb", errmsg) <> YAPI_SUCCESS) Then
Console.WriteLine("RegisterHub error:" + errmsg)
End
End If

If argv.Length < 2 Then usage()

m = YModule.FindModule(argv(1)) REM use serial or logical name
If (m.isOnline()) Then
If argv.Length > 2 Then
If argv(2) = "ON" Then m.set_beacon(Y_BEACON_ON)
If argv(2) = "OFF" Then m.set_beacon(Y_BEACON_OFF)
End If
Console.WriteLine("serial: " + m.get_serialNumber())
Console.WriteLine("logical name: " + m.get_logicalName())
Console.WriteLine("luminosity: " + Str(m.get_luminosity()))
Console.Write("beacon: ")
If (m.get_beacon() = Y_BEACON_ON) Then
Console.WriteLine("ON")
Else
Console.WriteLine("OFF")
End If
Console.WriteLine("upTime: " + Str(m.get_upTime() / 1000) + " sec")
Console.WriteLine("USB current: " + Str(m.get_usbCurrent()) + " mA")
Console.WriteLine("Logs:")
Console.WriteLine(m.get_lastLogs())
Else
Console.WriteLine(argv(1) + " not connected (check identification and USB cable)")
End If
YAPI.FreeAPI()
End Sub

End Module

Changing the module settings

Module Module1

Sub usage()

Console.WriteLine("usage: demo <serial or logical name> <new logical name>")
End
End Sub

Sub Main()
Dim argv() As String = System.Environment.GetCommandLineArgs()
Dim errmsg As String = ""
Dim newname As String
Dim m As YModule

If (argv.Length <> 3) Then usage()

REM Setup the API to use local USB devices
If YAPI.RegisterHub("usb", errmsg) <> YAPI_SUCCESS Then
Console.WriteLine("RegisterHub error: " + errmsg)
End
End If

m = YModule.FindModule(argv(1)) REM use serial or logical name
If m.isOnline() Then
newname = argv(2)
If (Not YAPI.CheckLogicalName(newname)) Then
Console.WriteLine("Invalid name (" + newname + ")")
End
End If
m.set_logicalName(newname)
m.saveToFlash() REM do not forget this
Console.Write("Module: serial= " + m.get_serialNumber)
Console.Write(" / name= " + m.get_logicalName())
Else
Console.Write("not connected (check identification and USB cable")
End If
YAPI.FreeAPI()

End Sub

End Module

Listing the modules

Obtaining the list of the connected modules is performed with the yFirstModule() function which returns the first module found. Then, you only need to call the nextModule() function of this object to find the following modules, and this as long as the returned value is not Nothing. Below a short example listing the connected modules.

Module Module1

Sub Main()
Dim M As ymodule
Dim errmsg As String = ""

REM Setup the API to use local USB devices
If YAPI.RegisterHub("usb", errmsg) <> YAPI_SUCCESS Then
Console.WriteLine("RegisterHub error: " + errmsg)
End
End If

Console.WriteLine("Device list")
M = YModule.FirstModule()
While M IsNot Nothing
Console.WriteLine(M.get_serialNumber() + " (" + M.get_productName() + ")")
M = M.nextModule()
End While
YAPI.FreeAPI()
End Sub

End Module

13.5. Error handling

If your code catches the exception and handles it, everything goes well.
If your program is running in debug mode, you can relatively easily determine where the problem happened and view the explanatory message linked to the exception.
Otherwise... the exception makes your program crash, bang!

14. Using Yocto-RS485 with C#

C# (pronounced C-Sharp) is an object-oriented programming language promoted by Microsoft, it is somewhat similar to Java. Like Visual-Basic and Delphi, it allows you to create Windows applications quite easily. All the examples and the project models are tested with Microsoft C# 2010 Express, freely available on the Microsoft web site³⁵.

Our programming library is also compatible with Mono, the open source version of C# that also works on Linux and MacOS. You will find on our web site various articles that describe how to configure Mono to use our library.

14.1. Installation

Download the Visual C# Yoctopuce library from the Yoctopuce web site³⁶. There is no setup program, simply copy the content of the zip file into the directory of your choice. You mostly need the content of the Sources directory. The other directories contain the documentation and a few sample programs. All sample projects are Visual C# 2010, projects, if you are using a previous version, you may have to recreate the projects structure from scratch.

14.2. Using the Yoctopuce API in a Visual C# project

The Visual C#.NET Yoctopuce library is composed of a DLL and of source files in Visual C#. The DLL is not a .NET DLL, but a classic DLL, written in C, which manages the low level communications with the modules³⁷. The source files in Visual C# manage the high level part of the API. Therefore, your need both this DLL and the .cs files of the sources directory to create a project managing Yoctopuce modules.

Configuring a Visual C# project

A file selection window opens. Select the yocto_api.cs file and the files corresponding to the functions of the Yoctopuce modules that your project is going to manage. If in doubt, select all the files.

Then add in the same manner the yapi.dll DLL, located in the Sources/dll directory³⁸. Then, from the Solution Explorer window, right click on the DLL, select Properties and in the Properties panel, set the Copy to output folder to always. You are now ready to use your Yoctopuce modules from Visual Studio.

14.3. Control of the SerialPort function

A few lines of code are enough to use a Yocto-RS485. Here is the skeleton of a C# code snipplet to use the SerialPort function.

[...]
// Enable detection of USB devices
string errmsg ="";
YAPI.RegisterHub("usb", errmsg);
[...]

// Retrieve the object used to interact with the device
YSerialPort serialport = YSerialPort.FindSerialPort("RS485MK1-123456.serialPort");

// Hot-plug is easy: just check that the device is online
if (serialport.isOnline())
{
// Use serialport.get_serialMode()
[...]
}

Let's look at these lines in more details.

YAPI.RegisterHub

YSerialPort.FindSerialPort

serialport = YSerialPort.FindSerialPort("RS485MK1-123456.serialPort");
serialport = YSerialPort.FindSerialPort("RS485MK1-123456.MyFunction");
serialport = YSerialPort.FindSerialPort("MyModule.serialPort");
serialport = YSerialPort.FindSerialPort("MyModule.MyFunction");
serialport = YSerialPort.FindSerialPort("MyFunction");

YSerialPort.FindSerialPort returns an object which you can then use at will to control the serial port.

isOnline

The isOnline() method of the object returned by YSerialPort.FindSerialPort allows you to know if the corresponding module is present and in working order.

modbusWrite* and modbusRead*

The modbusWrite*() and modbusRead*() method of the object returned by YFindSerialPort.FindSerialPort provides MODBUS communication overs the serial port.

A real example

Launch Microsoft Visual C# and open the corresponding sample project provided in the directory Examples/Doc-GettingStarted-Yocto-RS485 of the Yoctopuce library.

In this example, you will recognize the functions explained above, but this time used with all side materials needed to make it work nicely as a small demo.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
class Program
{

static void Main(string[] args)
{
string errmsg = "";

if (YAPI.RegisterHub("usb", ref errmsg) != YAPI.SUCCESS) {
Console.WriteLine("RegisterHub error: " + errmsg);
Environment.Exit(1);
}

YSerialPort serialPort;
if (args.Length > 0 && args[0] != "any") {
serialPort = YSerialPort.FindSerialPort(args[0]);
} else {
serialPort = YSerialPort.FirstSerialPort();
if (serialPort == null) {
Console.WriteLine("No module connected (check USB cable)");
Environment.Exit(1);
}
}
int slave, reg, val;
String cmd;
do {
Console.WriteLine("Please enter the MODBUS slave address (1...255)");
Console.Write("Slave: ");
slave = Convert.ToInt32(Console.ReadLine());
} while (slave < 1 || slave > 255);
do {
Console.WriteLine("Please select a Coil No (>=1), Input Bit No (>=10001+),");
Console.WriteLine(" Input Register No (>=30001) or Register No (>=40001)");
Console.Write("No: ");
reg = Convert.ToInt32(Console.ReadLine());
} while (reg < 1 || reg >= 50000 || (reg % 10000) == 0);
while (true) {
if (reg >= 40001) {
val = serialPort.modbusReadRegisters(slave, reg - 40001, 1)[0];
} else if (reg >= 30001) {
val = serialPort.modbusReadInputRegisters(slave, reg - 30001, 1)[0];
} else if (reg >= 10001) {
val = serialPort.modbusReadInputBits(slave, reg - 10001, 1)[0];
} else {
val = serialPort.modbusReadBits(slave, reg - 1, 1)[0];
}
Console.WriteLine("Current value: " + val.ToString());
Console.Write("Press ENTER to read again, Q to quit");
if ((reg % 30000) < 10000) {
Console.Write(" or enter a new value");
}
Console.Write(": ");
cmd = Console.ReadLine();
if (cmd == "q" || cmd == "Q") break;
if (cmd != "" && (reg % 30000) < 10000) {
val = Convert.ToInt32(cmd);
if (reg >= 30001) {
serialPort.modbusWriteRegister(slave, reg - 30001, val);
} else {
serialPort.modbusWriteBit(slave, reg - 1, val);
}
}
}
YAPI.FreeAPI();
}
}
}

14.4. Control of the module part

Each module can be controlled in a similar manner, you can find below a simple sample program displaying the main parameters of the module and enabling you to activate the localization beacon.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
class Program
{
static void usage()
{
string execname = System.AppDomain.CurrentDomain.FriendlyName;
Console.WriteLine("Usage:");
Console.WriteLine(execname + " <serial or logical name> [ON/OFF]");
System.Threading.Thread.Sleep(2500);
Environment.Exit(0);
}

static void Main(string[] args)
{
YModule m;
string errmsg = "";

if (YAPI.RegisterHub("usb", ref errmsg) != YAPI.SUCCESS) {
Console.WriteLine("RegisterHub error: " + errmsg);
Environment.Exit(0);
}

if (args.Length < 1) usage();

m = YModule.FindModule(args[0]); // use serial or logical name

if (m.isOnline()) {
if (args.Length >= 2) {
if (args[1].ToUpper() == "ON") {
m.set_beacon(YModule.BEACON_ON);
}
if (args[1].ToUpper() == "OFF") {
m.set_beacon(YModule.BEACON_OFF);
}
}

Console.WriteLine("serial: " + m.get_serialNumber());
Console.WriteLine("logical name: " + m.get_logicalName());
Console.WriteLine("luminosity: " + m.get_luminosity().ToString());
Console.Write("beacon: ");
if (m.get_beacon() == YModule.BEACON_ON)
Console.WriteLine("ON");
else
Console.WriteLine("OFF");
Console.WriteLine("upTime: " + (m.get_upTime() / 1000 ).ToString() + " sec");
Console.WriteLine("USB current: " + m.get_usbCurrent().ToString() + " mA");
Console.WriteLine("Logs:\r\n" + m.get_lastLogs());

} else {
Console.WriteLine(args[0] + " not connected (check identification and USB cable)");
}
YAPI.FreeAPI();
}
}
}

Each property xxx of the module can be read thanks to a method of type YModule.get_xxxx(), and properties which are not read-only can be modified with the help of the YModule.set_xxx() method. For more details regarding the used functions, refer to the API chapters.

Changing the module settings

When you want to modify the settings of a module, you only need to call the corresponding YModule.set_xxx() function. However, this modification is performed only in the random access memory (RAM) of the module: if the module is restarted, the modifications are lost. To memorize them persistently, it is necessary to ask the module to save its current configuration in its permanent memory. To do so, use the YModule.saveToFlash() method. Inversely, it is possible to force the module to forget its current settings by using the YModule.revertFromFlash() method. The short example below allows you to modify the logical name of a module.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
class Program
{
static void usage()
{
string execname = System.AppDomain.CurrentDomain.FriendlyName;
Console.WriteLine("Usage:");
Console.WriteLine("usage: demo <serial or logical name> <new logical name>");
System.Threading.Thread.Sleep(2500);
Environment.Exit(0);
}

static void Main(string[] args)
{
YModule m;
string errmsg = "";
string newname;

if (args.Length != 2) usage();

if (YAPI.RegisterHub("usb", ref errmsg) != YAPI.SUCCESS) {
Console.WriteLine("RegisterHub error: " + errmsg);
Environment.Exit(0);
}

m = YModule.FindModule(args[0]); // use serial or logical name

if (m.isOnline()) {
newname = args[1];
if (!YAPI.CheckLogicalName(newname)) {
Console.WriteLine("Invalid name (" + newname + ")");
Environment.Exit(0);
}

m.set_logicalName(newname);
m.saveToFlash(); // do not forget this

Console.Write("Module: serial= " + m.get_serialNumber());
Console.WriteLine(" / name= " + m.get_logicalName());
} else {
Console.Write("not connected (check identification and USB cable");
}
YAPI.FreeAPI();
}
}
}

Warning: the number of write cycles of the nonvolatile memory of the module is limited. When this limit is reached, nothing guaranties that the saving process is performed correctly. This limit, linked to the technology employed by the module micro-processor, is located at about 100000 cycles. In short, you can use the YModule.saveToFlash() function only 100000 times in the life of the module. Make sure you do not call this function within a loop.

Listing the modules

Obtaining the list of the connected modules is performed with the YModule.yFirstModule() function which returns the first module found. Then, you only need to call the nextModule() function of this object to find the following modules, and this as long as the returned value is not null. Below a short example listing the connected modules.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
YModule m;
string errmsg = "";

if (YAPI.RegisterHub("usb", ref errmsg) != YAPI.SUCCESS) {
Console.WriteLine("RegisterHub error: " + errmsg);
Environment.Exit(0);
}

Console.WriteLine("Device list");
m = YModule.FirstModule();
while (m != null) {
Console.WriteLine(m.get_serialNumber() + " (" + m.get_productName() + ")");
m = m.nextModule();
}
YAPI.FreeAPI();
}
}
}

14.5. Error handling

If your code catches the exception and handles it, everything goes well.
If your program is running in debug mode, you can relatively easily determine where the problem happened and view the explanatory message linked to the exception.
Otherwise... the exception makes your program crash, bang!

15. Using the Yocto-RS485 with Universal Windows Platform

Universal Windows Platform (UWP) is not a language per say, but a software platform created by Microsoft. This platform allows you to run a new type of applications: the universal Windows applications. These applications can work on all machines running under Windows 10. This includes computers, tablets, smart phones, XBox One, and also Windows IoT Core.

The Yoctopuce UWP library allows you to use Yoctopuce modules in a universal Windows application and is written in C# in its entirety. You can add it to a Visual Studio 2017³⁹ project.

15.1. Blocking and asynchronous functions

The Universal Windows Platform does not use the Win32 API but only the Windows Runtime API which is available on all the versions of Windows 10 and for any architecture. Thanks to this library, you can use UWP on all the Windows 10 versions, including Windows 10 IoT Core.

However, using the new UWP API has some consequences: the Windows Runtime API to access the USB ports is asynchronous, and therefore the Yoctopuce library must be asynchronous as well. Concretely, the asynchronous methods do not return a result directly but a Task or Task<> object and the result can be obtained later. Fortunately, the C# language, version 6, supports the async and await keywords, which simplifies using these functions enormously. You can thus use asynchronous functions in the same way as traditional functions as long as you respect the following two rules:

The method is declared as asynchronous with the async keyword
The await keyword is added when calling an asynchronous function

Example:

async Task<int> MyFunction(int val)
{
// do some long computation
...

return result;
}

int res = await MyFunction(1234);

Our library follows these two rules and can therefore use the await notation.

For you not to have to wonder wether a function is asynchronous or not, there is the following convention: all the public methods of the UWP library are asynchronous, that is that you must call them with the await keyword, except:

GetTickCount(), because measuring time in an asynchronous manner does not make a lot of sense...
FindModule(), FirstModule(), nextModule(), ... because detecting and enumerating modules is performed as a background task on internal structures which are managed transparently. It is therefore not necessary to use blocking functions while going though the lists of modules.

15.2. Installation

Download the Yoctopuce library for Universal Windows Platform from the Yoctopuce web site⁴⁰. There is no installation software, simply copy the content of the zip file in a directory of your choice. You essentially need the content of the Sources directory. The other directories contain documentation and a few sample programs. Sample projects are Visual Studio 2017 projects. Visual Studio 2017 is available on the Microsoft web site⁴¹.

15.3. Using the Yoctopuce API in a Visual Studio project

Start by creating your project. Then, from the Solution Explorer panel right click on your project and select Add then Existing element .

A file chooser opens: select all the files in the library Sources directory.

You then have the choice between simply adding the files to your project or adding them as a link (the Add button is actually a drop-down menu). In the first case, Visual Studio copies the selected files into your project. In the second case, Visual Studio simply creates a link to the original files. We recommend to use links, as a potential library update is thus much easier.

The Package.appxmanifest file

By default a Universal Windows application doesn't have access rights to the USB ports. If you want to access USB devices, you must imperatively declare it in the Package.appxmanifest file.

Unfortunately, the edition window of this file doesn't allow this operation and you must modify the Package.appxmanifest file by hand. In the "Solution Explorer" panel, right click on the Package.appxmanifest and select "View Code".

In this XML file, we must add a DeviceCapability node in the Capabilities node. This node must have a "Name" attribute with a "humaninterfacedevice" value.

Inside this node, you must declare all the modules that can be used. Concretely, for each module, you must add a "Device" node with an "Id" attribute, which has for value a character string "vidpid:USB_VENDORID USB_DEVICE_ID". The Yoctopuce USB_VENDORID is 24e0 and you can find the USB_DEVICE_ID of each Yoctopuce device in the documentation in the "Characteristics" section. Finally, the "Device" node must contain a "Function" node with the "Type" attribute with a value of "usage:ff00 0001".

For the Yocto-RS485, here is what you must add in the "Capabilities" node:

Unfortunately, it's not possible to write a rule authorizing all Yoctopuce modules. Therefore, you must imperatively add each module that you want to use.

15.4. Control of the SerialPort function

A few lines of code are enough to use a Yocto-RS485. Here is the skeleton of a C# code snippet to use the SerialPort function.

[...]
// Enable detection of USB devices
await YAPI.RegisterHub("usb");
[...]

// Retrieve the object used to interact with the device
YSerialPort serialport = YSerialPort.FindSerialPort("RS485MK1-123456.serialPort");

// Hot-plug is easy: just check that the device is online
if (await serialport.isOnline())
{
// Use serialport.get_serialMode()
[...]
}

[...]

Let us look at these lines in more details.

YAPI.RegisterHub

The YAPI.RegisterHub function initializes the Yoctopuce API and indicates where the modules should be looked for. The parameter is the address of the virtual hub able to see the devices. If the string "usb" is passed as parameter, the API works with modules locally connected to the machine. If the initialization does not succeed, an exception is thrown.

YSerialPort.FindSerialPort

serialport = YSerialPort.FindSerialPort("RS485MK1-123456.serialPort");
serialport = YSerialPort.FindSerialPort("RS485MK1-123456.MaFonction");
serialport = YSerialPort.FindSerialPort("MonModule.serialPort");
serialport = YSerialPort.FindSerialPort("MonModule.MaFonction");
serialport = YSerialPort.FindSerialPort("MaFonction");

YSerialPort.FindSerialPort returns an object which you can then use at will to control the serial port.

isOnline

The isOnline() method of the object returned by YSerialPort.FindSerialPort allows you to know if the corresponding module is present and in working order.

modbusWrite* and modbusRead*

The modbusWrite*() and modbusRead*() method of the object returned by YFindSerialPort.FindSerialPort provides MODBUS communication overs the serial port.

15.5. A real example

Launch Visual Studio and open the corresponding project provided in the directory Examples/Doc-GettingStarted-Yocto-RS485 of the Yoctopuce library.

Visual Studio projects contain numerous files, and most of them are not linked to the use of the Yoctopuce library. To simplify reading the code, we regrouped all the code that uses the library in the Demo class, located in the demo.cs file. Properties of this class correspond to the different fields displayed on the screen, and the Run() method contains the code which is run when the "Start" button is pushed.

In this example, you can recognize the functions explained above, but this time used with all the side materials needed to make it work nicely as a small demo.

using System;
using System.Diagnostics;
using System.Threading.Tasks;
using Windows.UI.Xaml.Controls;
using com.yoctopuce.YoctoAPI;

namespace Demo
{
public class Demo : DemoBase
{
public string HubURL { get; set; }
public string Target { get; set; }
public string Slave { get; set; }
public string Register { get; set; }
public string Value { get; set; }

public override async Task<int> Run()
{
try {
int slave = Convert.ToInt32(Slave);
if (slave < 1 || slave > 255) {
WriteLine("Invalid MODBUS slave address");
return -1;
}

int reg = Convert.ToInt32(Register);
if (reg < 1 || reg >= 50000 || (reg % 10000) == 0) {
WriteLine("Invalid MODBUS Register");
return -1;
}

await YAPI.RegisterHub(HubURL);

YSerialPort serialPort;
if (Target.ToLower() == "any") {
serialPort = YSerialPort.FirstSerialPort();
if (serialPort == null) {
WriteLine("No module connected (check USB cable) ");
return -1;
}
YModule ymod = await serialPort.get_module();
WriteLine("Using: " + await ymod.get_serialNumber());
} else {
serialPort = YSerialPort.FindSerialPort(Target + ".serialPort");
}

int val;
if (reg >= 40001) {
val = (await serialPort.modbusReadRegisters(slave, reg - 40001, 1))[0];
} else if (reg >= 30001) {
val = (await serialPort.modbusReadInputRegisters(slave, reg - 30001, 1))[0];
} else if (reg >= 10001) {
val = (await serialPort.modbusReadInputBits(slave, reg - 10001, 1))[0];
} else {
val = (await serialPort.modbusReadBits(slave, reg - 1, 1))[0];
}

WriteLine("Current value: " + val.ToString());

if (Value != "" && (reg % 30000) < 10000) {
val = Convert.ToInt32(Value);
if (reg >= 30001) {
await serialPort.modbusWriteRegister(slave, reg - 30001, val);
} else {
await serialPort.modbusWriteBit(slave, reg - 1, val);
}
}
} catch (YAPI_Exception ex) {
WriteLine("error: " + ex.Message);
}

YAPI.FreeAPI();
return 0;
}
}
}

15.6. Control of the module part

Each module can be controlled in a similar manner, you can find below a simple sample program displaying the main parameters of the module and enabling you to activate the localization beacon.

Changing the module settings

Warning: the number of write cycles of the nonvolatile memory of the module is limited. When this limit is reached, nothing guaranties that the saving process is performed correctly. This limit, linked to the technology employed by the module micro-processor, is located at about 100000 cycles. In short, you can use the YModule.saveToFlash() function only 100000 times in the life of the module. Make sure you do not call this function within a loop.

Listing the modules

using System;
using System.Diagnostics;
using System.Threading.Tasks;
using Windows.UI.Xaml.Controls;
using com.yoctopuce.YoctoAPI;

namespace Demo
{
public class Demo : DemoBase
{
public string HubURL { get; set; }

public override async Task<int> Run()
{
YModule m;
try {
await YAPI.RegisterHub(HubURL);

WriteLine("Device list");
m = YModule.FirstModule();
while (m != null) {
WriteLine(await m.get_serialNumber()
+ " (" + await m.get_productName() + ")");
m = m.nextModule();
}
} catch (YAPI_Exception ex) {
WriteLine("Error:" + ex.Message);
}
YAPI.FreeAPI();
return 0;
}
}
}

15.7. Error handling

In the Universal Windows Platform library, error handling is implemented with exceptions. You must therefore intercept and correctly handle these exceptions if you want to have a reliable project which does not crash as soon as you disconnect a module.

Library thrown exceptions are always of the YAPI_Exception type, so you can easily separate them from other exceptions in a try{...} catch{...} block.

Example:

try {
....
} catch (YAPI_Exception ex) {
Debug.WriteLine("Exception from Yoctopuce lib:" + ex.Message);
} catch (Exception ex) {
Debug.WriteLine("Other exceptions :" + ex.Message);
}

16. Using Yocto-RS485 with Delphi

Delphi is a descendent of Turbo-Pascal. Originally, Delphi was produced by Borland, Embarcadero now edits it. The strength of this language resides in its ease of use, as anyone with some notions of the Pascal language can develop a Windows application in next to no time. Its only disadvantage is to cost something⁴².

Delphi libraries are provided not as VCL components, but directly as source files. These files are compatible with most Delphi versions. ⁴³

To keep them simple, all the examples provided in this documentation are console applications. Obviously, the libraries work in a strictly identical way with VCL applications.

You will soon notice that the Delphi API defines many functions which return objects. You do not need to deallocate these objects yourself, the API does it automatically at the end of the application.

16.1. Preparation

Go to the Yoctopuce web site and download the Yoctopuce Delphi libraries⁴⁴. Uncompress everything in a directory of your choice, add the subdirectory sources in the list of directories of Delphi libraries.⁴⁵

By default, the Yoctopuce Delphi library uses the yapi.dll DLL, all the applications you will create with Delphi must have access to this DLL. The simplest way to ensure this is to make sure yapi.dll is located in the same directory as the executable file of your application.

16.2. Control of the SerialPort function

A few lines of code are enough to use a Yocto-RS485. Here is the skeleton of a Delphi code snipplet to use the SerialPort function.

uses yocto_api, yocto_serialport;

var errmsg: string;
serialport: TYSerialPort;

[...]
// Enable detection of USB devices
yRegisterHub('usb',errmsg)
[...]

// Retrieve the object used to interact with the device
serialport = yFindSerialPort("RS485MK1-123456.serialPort")

// Hot-plug is easy: just check that the device is online
if serialport.isOnline() then
begin
// Use serialport.get_serialMode()
[...]
end;
[...]

Let's look at these lines in more details.

yocto_api and yocto_serialport

These two units provide access to the functions allowing you to manage Yoctopuce modules. yocto_api must always be used, yocto_serialport is necessary to manage modules containing a serial port, such as Yocto-RS485.

yRegisterHub

The yRegisterHub function initializes the Yoctopuce API and specifies where the modules should be looked for. When used with the parameter 'usb', it will use the modules locally connected to the computer running the library. If the initialization does not succeed, this function returns a value different from YAPI_SUCCESS and errmsg contains the error message.

yFindSerialPort

The yFindSerialPort function allows you to find a serial port from the serial number of the module on which it resides and from its function name. You can also use logical names, as long as you have initialized them. Let us imagine a Yocto-RS485 module with serial number RS485MK1-123456 which you have named "MyModule", and for which you have given the serialPort function the name "MyFunction". The following five calls are strictly equivalent, as long as "MyFunction" is defined only once.

serialport := yFindSerialPort("RS485MK1-123456.serialPort");
serialport := yFindSerialPort("RS485MK1-123456.MyFunction");
serialport := yFindSerialPort("MyModule.serialPort");
serialport := yFindSerialPort("MyModule.MyFunction");
serialport := yFindSerialPort("MyFunction");

yFindSerialPort returns an object which you can then use at will to control the serial port.

isOnline

The isOnline() method of the object returned by yFindSerialPort allows you to know if the corresponding module is present and in working order.

modbusWrite* and modbusRead*

The modbusWrite*() and modbusRead*() method of the object returned by yFindSerialPort provides MODBUS communication over the serial port.

A real example

Launch your Delphi environment, copy the yapi.dll DLL in a directory, create a new console application in the same directory, and copy-paste the piece of code below:

In this example, you will recognize the functions explained above, but this time used with all side materials needed to make it work nicely as a small demo.

program helloworld;
{$APPTYPE CONSOLE}
uses
SysUtils,
Windows,
yocto_api,
yocto_serialport;

var
errmsg,line : string;
serialPort : TYserialport;
slave,reg: integer;
res : TLongIntArray;
cmd :string;
val : integer;
begin

// Setup the API to use local USB devices. You can
// use an IP address instead of 'usb' if the device
// is connected to a network.
if (YRegisterHub('usb', errmsg) <> YAPI_SUCCESS) then
begin
writeln('RegisterHub error: ' + errmsg);
halt;
end;

if (paramcount>1) then
serialPort := YFindSerialPort(paramstr(1))
else
begin
serialPort := YFirstSerialPort();
if (serialPort=nil) then
begin
writeln('No module connected (check cable)');
halt;
end;
end;

writeln('Please enter the MODBUS slave address (1...255)');
repeat
ReadLn(slave);
until (slave>0) and (slave<256);

writeln('Please select a Coil No (>=1), Input Bit No (>=10001+),');
writeln('Input Register No (>=30001) or Register No (>=40001)');
writeln('No: ');
repeat
ReadLn(reg);
until (reg >=1) and (reg<50000) and ((reg mod 10000)<> 0);

while (true) do
begin
if (reg>=40001) then res := serialPort.modbusReadRegisters(slave, reg-40001, 1)
else if (reg>=30001) then res := serialPort.modbusReadInputRegisters(slave, reg-30001, 1)
else if (reg>=10001) then res := serialPort.modbusReadInputBits(slave, reg-10001, 1)
else res := serialPort.modbusReadBits(slave, reg-1, 1);
val := res[0];
writeln('Current value: '+inttostr(val));
write('Press ENTER to read again, Q to quit');
if((reg mod 30000) < 10000) then write (' or enter a new value');
write(': ');
readLn(cmd);
if (cmd ='q') or (cmd ='Q') then halt;
if (cmd<>'') and ((reg mod 30000) < 10000) then
begin
val := strtoint(cmd);
if(reg >= 30001) then serialPort.modbusWriteRegister(slave, reg-30001, val)
else serialPort.modbusWriteBit(slave, reg-1, val);
end;
end;
yFreeAPI();

end.

16.3. Control of the module part

Each module can be controlled in a similar manner, you can find below a simple sample program displaying the main parameters of the module and enabling you to activate the localization beacon.

program modulecontrol;
{$APPTYPE CONSOLE}
uses
SysUtils,
yocto_api;

const
serial = 'RS485MK1-123456'; // use serial number or logical name

procedure refresh(module:Tymodule) ;
begin
if (module.isOnline()) then
begin
Writeln('');
Writeln('Serial : ' + module.get_serialNumber());
Writeln('Logical name : ' + module.get_logicalName());
Writeln('Luminosity : ' + intToStr(module.get_luminosity()));
Write('Beacon :');
if (module.get_beacon()=Y_BEACON_ON) then Writeln('on')
else Writeln('off');
Writeln('uptime : ' + intToStr(module.get_upTime() div 1000)+'s');
Writeln('USB current : ' + intToStr(module.get_usbCurrent())+'mA');
Writeln('Logs : ');
Writeln(module.get_lastlogs());
Writeln('');
Writeln('r : refresh / b:beacon ON / space : beacon off');
end
else Writeln('Module not connected (check identification and USB cable)');
end;

procedure beacon(module:Tymodule;state:integer);
begin
module.set_beacon(state);
refresh(module);
end;

var
module : TYModule;
c : char;
errmsg : string;

begin
// Setup the API to use local USB devices
if yRegisterHub('usb', errmsg)<>YAPI_SUCCESS then
begin
Write('RegisterHub error: '+errmsg);
exit;
end;

module := yFindModule(serial);
refresh(module);

repeat
read(c);
case c of
'r': refresh(module);
'b': beacon(module,Y_BEACON_ON);
' ': beacon(module,Y_BEACON_OFF);
end;
until c = 'x';
yFreeAPI();
end.

Changing the module settings

program savesettings;
{$APPTYPE CONSOLE}
uses
SysUtils,
yocto_api;

const
serial = 'RS485MK1-123456'; // use serial number or logical name

var
module : TYModule;
errmsg : string;
newname : string;

begin
// Setup the API to use local USB devices
if yRegisterHub('usb', errmsg)<>YAPI_SUCCESS then
begin
Write('RegisterHub error: '+errmsg);
exit;
end;

module := yFindModule(serial);
if (not(module.isOnline)) then
begin
writeln('Module not connected (check identification and USB cable)');
exit;
end;

Writeln('Current logical name : '+module.get_logicalName());
Write('Enter new name : ');
Readln(newname);
if (not(yCheckLogicalName(newname))) then
begin
Writeln('invalid logical name');
exit;
end;
module.set_logicalName(newname);
module.saveToFlash();
yFreeAPI();
Writeln('logical name is now : '+module.get_logicalName());
end.

Listing the modules

Obtaining the list of the connected modules is performed with the yFirstModule() function which returns the first module found. Then, you only need to call the nextModule() function of this object to find the following modules, and this as long as the returned value is not nil. Below a short example listing the connected modules.

program inventory;
{$APPTYPE CONSOLE}
uses
SysUtils,
yocto_api;

var
module : TYModule;
errmsg : string;

begin
// Setup the API to use local USB devices
if yRegisterHub('usb', errmsg)<>YAPI_SUCCESS then
begin
Write('RegisterHub error: '+errmsg);
exit;
end;

Writeln('Device list');

module := yFirstModule();
while module<>nil do
begin
Writeln( module.get_serialNumber()+' ('+module.get_productName()+')');
module := module.nextModule();
end;
yFreeAPI();

end.

16.4. Error handling

If your code catches the exception and handles it, everything goes well.
If your program is running in debug mode, you can relatively easily determine where the problem happened and view the explanatory message linked to the exception.
Otherwise... the exception makes your program crash, bang!

17. Using the Yocto-RS485 with Python

Python is an interpreted object oriented language developed by Guido van Rossum. Among its advantages is the fact that it is free, and the fact that it is available for most platforms, Windows as well as UNIX. It is an ideal language to write small scripts on a napkin. The Yoctopuce library is compatible with Python 2.6+ and 3+. It works under Windows, Mac OS X, and Linux, Intel as well as ARM. The library was tested with Python 2.6 and Python 3.2. Python interpreters are available on the Python web site⁴⁶.

17.1. Source files

The Yoctopuce library classes⁴⁷ for Python that you will use are provided as source files. Copy all the content of the Sources directory in the directory of your choice and add this directory to the PYTHONPATH environment variable. If you use an IDE to program in Python, refer to its documentation to configure it so that it automatically finds the API source files.

17.2. Dynamic library

A section of the low-level library is written in C, but you should not need to interact directly with it: it is provided as a DLL under Windows, as a .so files under UNIX, and as a .dylib file under Mac OS X. Everything was done to ensure the simplest possible interaction from Python: the distinct versions of the dynamic library corresponding to the distinct operating systems and architectures are stored in the cdll directory. The API automatically loads the correct file during its initialization. You should not have to worry about it.

If you ever need to recompile the dynamic library, its complete source code is located in the Yoctopuce C++ library.

17.3. Control of the SerialPort function

A few lines of code are enough to use a Yocto-RS485. Here is the skeleton of a Python code snipplet to use the SerialPort function.

[...]
# Enable detection of USB devices
errmsg=YRefParam()
YAPI.RegisterHub("usb",errmsg)
[...]

# Retrieve the object used to interact with the device
serialport = YSerialPort.FindSerialPort("RS485MK1-123456.serialPort")

# Hot-plug is easy: just check that the device is online
if serialport.isOnline():
# Use serialport.get_serialMode()
[...]

[...]

Let's look at these lines in more details.

YAPI.RegisterHub

The yAPI.RegisterHub function initializes the Yoctopuce API and indicates where the modules should be looked for. When used with the parameter "usb", it will use the modules locally connected to the computer running the library. If the initialization does not succeed, this function returns a value different from YAPI.SUCCESS and errmsg contains the error message.

YSerialPort.FindSerialPort

YSerialPort.FindSerialPort returns an object which you can then use at will to control the serial port.

isOnline

The isOnline() method of the object returned by YSerialPort.FindSerialPort allows you to know if the corresponding module is present and in working order.

modbusWrite* and modbusRead*

The modbusWrite*() and modbusRead*() method of the object returned by YFindSerialPort.FindSerialPort provides MODBUS communication overs the serial port.

A real example

Launch Python and open the corresponding sample script provided in the directory Examples/Doc-GettingStarted-Yocto-RS485 of the Yoctopuce library.

In this example, you will recognize the functions explained above, but this time used with all side materials needed to make it work nicely as a small demo.

#!/usr/bin/python
# -*- coding: utf-8 -*-
import os, sys

from yocto_api import *
from yocto_serialport import *

# Setup the API to use local USB devices. You can
# use an IP address instead of 'usb' if the device
# is connected to a network.

errmsg = YRefParam()
if YAPI.RegisterHub("usb", errmsg) != YAPI.SUCCESS:
sys.exit("init error" + errmsg.value)

if len(sys.argv) > 1:
serialPort = YSerialPort.FindSerialPort(sys.argv[1])
else:
serialPort = YSerialPort.FirstSerialPort()
if serialPort is None:
sys.exit('No module connected (check cable)')

print("Please enter the MODBUS slave address (1...255)")
slave = 0
while (slave < 1) or (slave > 255):
slave = int(input("slave: ")) # use raw_input in python 2.x

reg = 0
while (reg < 1) or (reg >= 50000) or (reg % 10000) == 0:
print("Please select a Coil No (>=1), Input Bit No (>=10001+),")
print("Input Register No (>=30001) or Register No (>=40001)")
reg = int(input("No: ")) # use raw_input in python 2.x

while serialPort.isOnline():
if reg >= 40001:
val = serialPort.modbusReadRegisters(slave, reg - 40001, 1)[0]
elif reg >= 30001:
val = serialPort.modbusReadInputRegisters(slave, reg - 30001, 1)[0]
elif reg >= 10001:
val = serialPort.modbusReadInputBits(slave, reg - 10001, 1)[0]
else:
val = serialPort.modbusReadBits(slave, reg - 1, 1)[0]

print("Current value: " + str(val))
print("Press ENTER to read again, Q to quit")
if (reg % 30000) < 10000:
print(" or enter a new value")

cmd = input(": ") # use raw_input in python 2.x
if (cmd == "q") or (cmd == "Q"):
sys.exit()

if cmd != "" and ((reg % 30000) < 10000):
val = int(cmd)
if reg >= 30001:
serialPort.modbusWriteRegister(slave, reg - 30001, val)
else:
serialPort.modbusWriteBit(slave, reg - 1, val)
YAPI.FreeAPI()

17.4. Control of the module part

Each module can be controlled in a similar manner, you can find below a simple sample program displaying the main parameters of the module and enabling you to activate the localization beacon.

#!/usr/bin/python
# -*- coding: utf-8 -*-
import os, sys

from yocto_api import *

def usage():
sys.exit("usage: demo <serial or logical name> [ON/OFF]")

errmsg = YRefParam()
if YAPI.RegisterHub("usb", errmsg) != YAPI.SUCCESS:
sys.exit("RegisterHub error: " + str(errmsg))

if len(sys.argv) < 2:
usage()

m = YModule.FindModule(sys.argv[1]) # # use serial or logical name

if m.isOnline():
if len(sys.argv) > 2:
if sys.argv[2].upper() == "ON":
m.set_beacon(YModule.BEACON_ON)
if sys.argv[2].upper() == "OFF":
m.set_beacon(YModule.BEACON_OFF)

print("serial: " + m.get_serialNumber())
print("logical name: " + m.get_logicalName())
print("luminosity: " + str(m.get_luminosity()))
if m.get_beacon() == YModule.BEACON_ON:
print("beacon: ON")
else:
print("beacon: OFF")
print("upTime: " + str(m.get_upTime() / 1000) + " sec")
print("USB current: " + str(m.get_usbCurrent()) + " mA")
print("logs:\n" + m.get_lastLogs())
else:
print(sys.argv[1] + " not connected (check identification and USB cable)")
YAPI.FreeAPI()

Changing the module settings

#!/usr/bin/python
# -*- coding: utf-8 -*-
import os, sys

from yocto_api import *

def usage():
sys.exit("usage: demo <serial or logical name> <new logical name>")

if len(sys.argv) != 3:
usage()

errmsg = YRefParam()
if YAPI.RegisterHub("usb", errmsg) != YAPI.SUCCESS:
sys.exit("RegisterHub error: " + str(errmsg))

m = YModule.FindModule(sys.argv[1]) # use serial or logical name
if m.isOnline():
newname = sys.argv[2]
if not YAPI.CheckLogicalName(newname):
sys.exit("Invalid name (" + newname + ")")
m.set_logicalName(newname)
m.saveToFlash() # do not forget this
print("Module: serial= " + m.get_serialNumber() + " / name= " + m.get_logicalName())
else:
sys.exit("not connected (check identification and USB cable")
YAPI.FreeAPI()

Warning: the number of write cycles of the nonvolatile memory of the module is limited. When this limit is reached, nothing guaranties that the saving process is performed correctly. This limit, linked to the technology employed by the module micro-processor, is located at about 100000 cycles. In short, you can use the YModule.saveToFlash() function only 100000 times in the life of the module. Make sure you do not call this function within a loop.

Listing the modules

#!/usr/bin/python
# -*- coding: utf-8 -*-
import os, sys

from yocto_api import *

errmsg = YRefParam()

# Setup the API to use local USB devices
if YAPI.RegisterHub("usb", errmsg) != YAPI.SUCCESS:
sys.exit("init error" + str(errmsg))

print('Device list')

module = YModule.FirstModule()
while module is not None:
print(module.get_serialNumber() + ' (' + module.get_productName() + ')')
module = module.nextModule()
YAPI.FreeAPI()

17.5. Error handling

If your code catches the exception and handles it, everything goes well.
If your program is running in debug mode, you can relatively easily determine where the problem happened and view the explanatory message linked to the exception.
Otherwise... the exception makes your program crash, bang!

18. Using the Yocto-RS485 with Java

Java is an object oriented language created by Sun Microsystem. Beside being free, its main strength is its portability. Unfortunately, this portability has an excruciating price. In Java, hardware abstraction is so high that it is almost impossible to work directly with the hardware. Therefore, the Yoctopuce API does not support native mode in regular Java. The Java API needs a Virtual Hub to communicate with Yoctopuce devices.

18.1. Getting ready

Go to the Yoctopuce web site and download the following items:

The Java programming library⁴⁸
The VirtualHub software⁴⁹ for Windows, Mac OS X or Linux, depending on your OS

The library is available as source files as well as a jar file. Decompress the library files in a folder of your choice, connect your modules, run the VirtualHub software, and you are ready to start your first tests. You do not need to install any driver.

18.2. Control of the SerialPort function

A few lines of code are enough to use a Yocto-RS485. Here is the skeleton of a Java code snippet to use the SerialPort function.

[...]
// Get access to your device, through the VirtualHub running locally
YAPI.RegisterHub("127.0.0.1");
[...]

// Retrieve the object used to interact with the device
serialport = YSerialPort.FindSerialPort("RS485MK1-123456.serialPort");

// Hot-plug is easy: just check that the device is online
if (serialport.isOnline())
{
// Use serialport.get_serialMode()
[...]
}

[...]

Let us look at these lines in more details.

YAPI.RegisterHub

The yAPI.RegisterHub function initializes the Yoctopuce API and indicates where the modules should be looked for. The parameter is the address of the Virtual Hub able to see the devices. If the initialization does not succeed, an exception is thrown.

YSerialPort.FindSerialPort

YSerialPort.FindSerialPort returns an object which you can then use at will to control the serial port.

isOnline

The isOnline() method of the object returned by YSerialPort.FindSerialPort allows you to know if the corresponding module is present and in working order.

modbusWrite* and modbusRead*

The modbusWrite*() and modbusRead*() method of the object returned by YFindSerialPort.FindSerialPort provides MODBUS communication overs the serial port.

A real example

Launch you Java environment and open the corresponding sample project provided in the directory Examples/Doc-GettingStarted-Yocto-RS485 of the Yoctopuce library.

In this example, you will recognize the functions explained above, but this time used with all the side materials needed to make it work nicely as a small demo.

import com.yoctopuce.YoctoAPI.*;
import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Demo {

public static void main(String[] args) {
try {
// setup the API to use local VirtualHub
YAPI.RegisterHub("127.0.0.1");
} catch (YAPI_Exception ex) {
System.out.println("Cannot contact VirtualHub on 127.0.0.1 (" + ex.getLocalizedMessage() + ")");
System.out.println("Ensure that the VirtualHub application is running");
System.exit(1);
}

YSerialPort serialPort;
if (args.length > 0) {
serialPort = YSerialPort.FindSerialPort(args[0]);
} else {
serialPort = YSerialPort.FirstSerialPort();
if (serialPort == null) {
System.out.println("No module connected (check USB cable)");
System.exit(1);
}
}

int slave, reg, val;
String cmd;

InputStreamReader inputStreamReader = new InputStreamReader(System.in);
BufferedReader console = new BufferedReader(inputStreamReader);
try {
do {
System.out.println("Please enter the MODBUS slave address (1...255)");
System.out.print("Slave: ");
slave = Integer.parseInt(console.readLine());
} while(slave < 1 || slave > 255);
do {
System.out.println("Please select a Coil No (>=1), Input Bit No (>=10001+),");
System.out.println(" Input Register No (>=30001) or Register No (>=40001)");
System.out.print("No: ");
reg = Integer.parseInt(console.readLine());
} while(reg < 1 || reg >= 50000 || (reg % 10000) == 0);
while(true) {
if(reg >= 40001) {
val = serialPort.modbusReadRegisters(slave, reg-40001, 1).get(0);
} else if(reg >= 30001) {
val = serialPort.modbusReadInputRegisters(slave, reg-30001, 1).get(0);
} else if(reg >= 10001) {
val = serialPort.modbusReadInputBits(slave, reg-10001, 1).get(0);
} else {
val = serialPort.modbusReadBits(slave, reg-1, 1).get(0);
}
System.out.println("Current value: "+Integer.toString(val));
System.out.print("Press ENTER to read again, Q to quit");
if((reg % 30000) < 10000) {
System.out.print(" or enter a new value");
}
System.out.print(": ");
cmd = console.readLine();
if(cmd.equals("q") || cmd.equals("Q")) break;
if(!cmd.equals("") && (reg % 30000) < 10000) {
val = Integer.parseInt(cmd);
if(reg >= 30001) {
serialPort.modbusWriteRegister(slave, reg-30001, val);
} else {
serialPort.modbusWriteBit(slave, reg-1, val);
}
}
}
} catch(Exception ex) {
ex.printStackTrace();
}

YAPI.FreeAPI();
}
}

18.3. Control of the module part

Each module can be controlled in a similar manner, you can find below a simple sample program displaying the main parameters of the module and enabling you to activate the localization beacon.

import com.yoctopuce.YoctoAPI.*;
import java.util.logging.Level;
import java.util.logging.Logger;

public class Demo {

public static void main(String[] args)
{
try {
// setup the API to use local VirtualHub
YAPI.RegisterHub("127.0.0.1");
} catch (YAPI_Exception ex) {
System.out.println("Cannot contact VirtualHub on 127.0.0.1 (" + ex.getLocalizedMessage() + ")");
System.out.println("Ensure that the VirtualHub application is running");
System.exit(1);
}
System.out.println("usage: demo [serial or logical name] [ON/OFF]");

YModule module;
if (args.length == 0) {
module = YModule.FirstModule();
if (module == null) {
System.out.println("No module connected (check USB cable)");
System.exit(1);
}
} else {
module = YModule.FindModule(args[0]); // use serial or logical name
}

try {
if (args.length > 1) {
if (args[1].equalsIgnoreCase("ON")) {
module.setBeacon(YModule.BEACON_ON);
} else {
module.setBeacon(YModule.BEACON_OFF);
}
}
System.out.println("serial: " + module.get_serialNumber());
System.out.println("logical name: " + module.get_logicalName());
System.out.println("luminosity: " + module.get_luminosity());
if (module.get_beacon() == YModule.BEACON_ON) {
System.out.println("beacon: ON");
} else {
System.out.println("beacon: OFF");
}
System.out.println("upTime: " + module.get_upTime() / 1000 + " sec");
System.out.println("USB current: " + module.get_usbCurrent() + " mA");
System.out.println("logs:\n" + module.get_lastLogs());
} catch (YAPI_Exception ex) {
System.out.println(args[1] + " not connected (check identification and USB cable)");
}
YAPI.FreeAPI();
}
}

Changing the module settings

import com.yoctopuce.YoctoAPI.*;

public class Demo {

public static void main(String[] args)
{
try {
// setup the API to use local VirtualHub
YAPI.RegisterHub("127.0.0.1");
} catch (YAPI_Exception ex) {
System.out.println("Cannot contact VirtualHub on 127.0.0.1 (" + ex.getLocalizedMessage() + ")");
System.out.println("Ensure that the VirtualHub application is running");
System.exit(1);
}

if (args.length != 2) {
System.out.println("usage: demo <serial or logical name> <new logical name>");
System.exit(1);
}

YModule m;
String newname;

m = YModule.FindModule(args[0]); // use serial or logical name

try {
newname = args[1];
if (!YAPI.CheckLogicalName(newname))
{
System.out.println("Invalid name (" + newname + ")");
System.exit(1);
}

m.set_logicalName(newname);
m.saveToFlash(); // do not forget this

System.out.println("Module: serial= " + m.get_serialNumber());
System.out.println(" / name= " + m.get_logicalName());
} catch (YAPI_Exception ex) {
System.out.println("Module " + args[0] + "not connected (check identification and USB cable)");
System.out.println(ex.getMessage());
System.exit(1);
}

YAPI.FreeAPI();
}
}

Warning: the number of write cycles of the nonvolatile memory of the module is limited. When this limit is reached, nothing guaranties that the saving process is performed correctly. This limit, linked to the technology employed by the module micro-processor, is located at about 100000 cycles. In short, you can use the YModule.saveToFlash() function only 100000 times in the life of the module. Make sure you do not call this function within a loop.

Listing the modules

18.4. Error handling

In the Java API, error handling is implemented with exceptions. Therefore you must catch and handle correctly all exceptions that might be thrown by the API if you do not want your software to crash as soon as you unplug a device.

19. Using the Yocto-RS485 with Android

To tell the truth, Android is not a programming language, it is an operating system developed by Google for mobile appliances such as smart phones and tablets. But it so happens that under Android everything is programmed with the same programming language: Java. Nevertheless, the programming paradigms and the possibilities to access the hardware are slightly different from classical Java, and this justifies a separate chapter on Android programming.

19.1. Native access and VirtualHub

In the opposite to the classical Java API, the Java for Android API can access USB modules natively. However, as there is no VirtualHub running under Android, it is not possible to remotely control Yoctopuce modules connected to a machine under Android. Naturally, the Java for Android API remains perfectly able to connect itself to a VirtualHub running on another OS.

19.2. Getting ready

Go to the Yoctopuce web site and download the Java for Android programming library⁵⁰. The library is available as source files, and also as a jar file. Connect your modules, decompress the library files in the directory of your choice, and configure your Android programming environment so that it can find them.

To keep them simple, all the examples provided in this documentation are snippets of Android applications. You must integrate them in your own Android applications to make them work. However, your can find complete applications in the examples provided with the Java for Android library.

19.3. Compatibility

In an ideal world, you would only need to have a smart phone running under Android to be able to make Yoctopuce modules work. Unfortunately, it is not quite so in the real world. A machine running under Android must fulfil to a few requirements to be able to manage Yoctopuce USB modules natively.

Android 4.x

Android 4.0 (api 14) and following are officially supported. Theoretically, support of USB host functions since Android 3.1. But be aware that the Yoctopuce Java for Android API is regularly tested only from Android 4 onwards.

USB host support

Naturally, not only must your machine have a USB port, this port must also be able to run in host mode. In host mode, the machine literally takes control of the devices which are connected to it. The USB ports of a desktop computer, for example, work in host mode. The opposite of the host mode is the device mode. USB keys, for instance, work in device mode: they must be controlled by a host. Some USB ports are able to work in both modes, they are OTG (On The Go) ports. It so happens that many mobile devices can only work in device mode: they are designed to be connected to a charger or a desktop computer, and nothing else. It is therefore highly recommended to pay careful attention to the technical specifications of a product working under Android before hoping to make Yoctopuce modules work with it.

Unfortunately, having a correct version of Android and USB ports working in host mode is not enough to guaranty that Yoctopuce modules will work well under Android. Indeed, some manufacturers configure their Android image so that devices other than keyboard and mass storage are ignored, and this configuration is hard to detect. As things currently stand, the best way to know if a given Android machine works with Yoctopuce modules consists in trying.

Supported hardware

The library is tested and validated on the following machines:

Samsung Galaxy S3
Samsung Galaxy Note 2
Google Nexus 5
Google Nexus 7
Acer Iconia Tab A200
Asus Tranformer Pad TF300T
Kurio 7

If your Android machine is not able to control Yoctopuce modules natively, you still have the possibility to remotely control modules driven by a VirtualHub on another OS, or a YoctoHub ⁵¹.

19.4. Activating the USB port under Android

By default, Android does not allow an application to access the devices connected to the USB port. To enable your application to interact with a Yoctopuce module directly connected on your tablet on a USB port, a few additional steps are required. If you intend to interact only with modules connected on another machine through the network, you can ignore this section.

In your AndroidManifest.xml, you must declare using the "USB Host" functionality by adding the <uses-feature android:name="android.hardware.usb.host" /> tag in the manifest section.

When first accessing a Yoctopuce module, Android opens a window to inform the user that the application is going to access the connected module. The user can deny or authorize access to the device. If the user authorizes the access, the application can access the connected device as long as it stays connected. To enable the Yoctopuce library to correctly manage these authorizations, your must provide a pointer on the application context by calling the EnableUSBHost method of the YAPI class before the first USB access. This function takes as arguments an object of the android.content.Context class (or of a subclass). As the Activity class is a subclass of Context, it is simpler to call YAPI.EnableUSBHost(this); in the method onCreate of your application. If the object passed as parameter is not of the correct type, a YAPI_Exception exception is generated.

...
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
try {
// Pass the application Context to the Yoctopuce Library
YAPI.EnableUSBHost(this);
} catch (YAPI_Exception e) {
Log.e("Yocto",e.getLocalizedMessage());
}
}
...

Autorun

It is possible to register your application as a default application for a USB module. In this case, as soon as a module is connected to the system, the application is automatically launched. You must add <action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED"/> in the section <intent-filter> of the main activity. The section <activity> must have a pointer to an XML file containing the list of USB modules which can run the application.

The XML file containing the list of modules allowed to run the application must be saved in the res/xml directory. This file contains a list of USB vendorId and deviceID in decimal. The following example runs the application as soon as a Yocto-Relay or a YoctoPowerRelay is connected. You can find the vendorID and the deviceID of Yoctopuce modules in the characteristics section of the documentation.

<?xml version="1.0" encoding="utf-8"?>

<resources>
<usb-device vendor-id="9440" product-id="12" />
<usb-device vendor-id="9440" product-id="13" />
</resources>

19.5. Control of the SerialPort function

A few lines of code are enough to use a Yocto-RS485. Here is the skeleton of a Java code snippet to use the SerialPort function.

[...]
// Enable detection of USB devices
YAPI.EnableUSBHost(this);
YAPI.RegisterHub("usb");
[...]
// Retrieve the object used to interact with the device
serialport = YSerialPort.FindSerialPort("RS485MK1-123456.serialPort");

// Hot-plug is easy: just check that the device is online
if (serialport.isOnline()) {
// Use serialport.get_serialMode()
[...]
}

[...]

Let us look at these lines in more details.

YAPI.EnableUSBHost

The YAPI.EnableUSBHost function initializes the API with the Context of the current application. This function takes as argument an object of the android.content.Context class (or of a subclass). If you intend to connect your application only to other machines through the network, this function is facultative.

YAPI.RegisterHub

The yAPI.RegisterHub function initializes the Yoctopuce API and indicates where the modules should be looked for. The parameter is the address of the virtual hub able to see the devices. If the string "usb" is passed as parameter, the API works with modules locally connected to the machine. If the initialization does not succeed, an exception is thrown.

YSerialPort.FindSerialPort

YSerialPort.FindSerialPort returns an object which you can then use at will to control the serial port.

isOnline

The isOnline() method of the object returned by YSerialPort.FindSerialPort allows you to know if the corresponding module is present and in working order.

modbusWrite* and modbusRead*

The modbusWrite*() and modbusRead*() method of the object returned by YFindSerialPort.FindSerialPort provides MODBUS communication overs the serial port.

A real example

Launch you Java environment and open the corresponding sample project provided in the directory Examples//Doc-Examples of the Yoctopuce library.

In this example, you can recognize the functions explained above, but this time used with all the side materials needed to make it work nicely as a small demo.

package com.yoctopuce.doc_examples;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.Spinner;
import android.widget.Switch;
import android.widget.TextView;
import android.widget.Toast;

import com.yoctopuce.YoctoAPI.YAPI;
import com.yoctopuce.YoctoAPI.YAPI_Exception;
import com.yoctopuce.YoctoAPI.YModule;
import com.yoctopuce.YoctoAPI.YSerialPort;

public class GettingStarted_Yocto_RS485 extends Activity implements OnItemSelectedListener
{

private ArrayAdapter<String> aa;
private YModule module = null;
private TextView resultTextView;
private EditText valueEditText;
private EditText registerEditText;
private EditText slaveEditText;
private Spinner my_spin;

@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.gettingstarted_yocto_rs485);
my_spin = (Spinner) findViewById(R.id.spinner1);
my_spin.setOnItemSelectedListener(this);
aa = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item);
aa.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
my_spin.setAdapter(aa);
slaveEditText = (EditText) findViewById(R.id.slavefield);
registerEditText = (EditText) findViewById(R.id.registerfield);
valueEditText = (EditText) findViewById(R.id.valuefield);
resultTextView = (TextView) findViewById(R.id.resultvalue);
}

@Override
protected void onStart()
{
super.onStart();

try {
aa.clear();
YAPI.EnableUSBHost(this);
YAPI.RegisterHub("usb");
YSerialPort r = YSerialPort.FirstSerialPort();
while (r != null) {
String hwid = r.get_hardwareId();
aa.add(hwid);
r = r.nextSerialPort();
}
} catch (YAPI_Exception e) {
e.printStackTrace();
}
// refresh Spinner with detected relay
aa.notifyDataSetChanged();
}

@Override
protected void onStop()
{
super.onStop();
YAPI.FreeAPI();
}

private int _doModbus(String hwid, String slavefield, String registerfield, String cmdfield)
{
int slave;
int reg;
try {
slave = Integer.parseInt(slavefield);
reg = Integer.parseInt(registerfield);
} catch (NumberFormatException ex) {
Toast.makeText(this,ex.toString(),Toast.LENGTH_LONG).show();
return 0;
}
try {
YSerialPort serialPort = YSerialPort.FindSerialPort(hwid);
// send new value to modbus device
if(!cmdfield.equals("") && (reg % 30000) < 10000) {
int cmd = Integer.parseInt(cmdfield);
if(reg >= 30001) {
serialPort.modbusWriteRegister(slave, reg-30001, cmd);
} else {
serialPort.modbusWriteBit(slave, reg-1, cmd);
}
}
// read it again

int val;
if(reg >= 40001) {
val = serialPort.modbusReadRegisters(slave, reg-40001, 1).get(0);
} else if(reg >= 30001) {
val = serialPort.modbusReadInputRegisters(slave, reg-30001, 1).get(0);
} else if(reg >= 10001) {
val = serialPort.modbusReadInputBits(slave, reg-10001, 1).get(0);
} else {
val = serialPort.modbusReadBits(slave, reg-1, 1).get(0);
}
return val;
} catch (YAPI_Exception e) {
e.printStackTrace();
}
return 0;
}

@Override
public void onItemSelected(AdapterView<?> parent, View view, int pos, long id)
{
resultTextView.setText("");
}

@Override
public void onNothingSelected(AdapterView<?> arg0)
{
}

public void refreshInfo(View view)
{
Object selectedItem = my_spin.getSelectedItem();
if (selectedItem!=null) {
String hwid = selectedItem.toString();
int val = _doModbus(hwid, slaveEditText.getText().toString(),
registerEditText.getText().toString(), valueEditText.getText().toString());
resultTextView.setText(Integer.toString(val));
}
}

}

19.6. Control of the module part

Each module can be controlled in a similar manner, you can find below a simple sample program displaying the main parameters of the module and enabling you to activate the localization beacon.

package com.yoctopuce.doc_examples;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.ArrayAdapter;
import android.widget.Spinner;
import android.widget.Switch;
import android.widget.TextView;

import com.yoctopuce.YoctoAPI.YAPI;
import com.yoctopuce.YoctoAPI.YAPI_Exception;
import com.yoctopuce.YoctoAPI.YModule;

public class ModuleControl extends Activity implements OnItemSelectedListener
{

private ArrayAdapter<String> aa;
private YModule module = null;

@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.modulecontrol);
Spinner my_spin = (Spinner) findViewById(R.id.spinner1);
my_spin.setOnItemSelectedListener(this);
aa = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item);
aa.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
my_spin.setAdapter(aa);
}

@Override
protected void onStart()
{
super.onStart();

try {
aa.clear();
YAPI.EnableUSBHost(this);
YAPI.RegisterHub("usb");
YModule r = YModule.FirstModule();
while (r != null) {
String hwid = r.get_hardwareId();
aa.add(hwid);
r = r.nextModule();
}
} catch (YAPI_Exception e) {
e.printStackTrace();
}
// refresh Spinner with detected relay
aa.notifyDataSetChanged();
}

@Override
protected void onStop()
{
super.onStop();
YAPI.FreeAPI();
}

private void DisplayModuleInfo()
{
TextView field;
if (module == null)
return;
try {
field = (TextView) findViewById(R.id.serialfield);
field.setText(module.getSerialNumber());
field = (TextView) findViewById(R.id.logicalnamefield);
field.setText(module.getLogicalName());
field = (TextView) findViewById(R.id.luminosityfield);
field.setText(String.format("%d%%", module.getLuminosity()));
field = (TextView) findViewById(R.id.uptimefield);
field.setText(module.getUpTime() / 1000 + " sec");
field = (TextView) findViewById(R.id.usbcurrentfield);
field.setText(module.getUsbCurrent() + " mA");
Switch sw = (Switch) findViewById(R.id.beaconswitch);
sw.setChecked(module.getBeacon() == YModule.BEACON_ON);
field = (TextView) findViewById(R.id.logs);
field.setText(module.get_lastLogs());

} catch (YAPI_Exception e) {
e.printStackTrace();
}
}

@Override
public void onItemSelected(AdapterView<?> parent, View view, int pos, long id)
{
String hwid = parent.getItemAtPosition(pos).toString();
module = YModule.FindModule(hwid);
DisplayModuleInfo();
}

@Override
public void onNothingSelected(AdapterView<?> arg0)
{
}

public void refreshInfo(View view)
{
DisplayModuleInfo();
}

public void toggleBeacon(View view)
{
if (module == null)
return;
boolean on = ((Switch) view).isChecked();

try {
if (on) {
module.setBeacon(YModule.BEACON_ON);
} else {
module.setBeacon(YModule.BEACON_OFF);
}
} catch (YAPI_Exception e) {
e.printStackTrace();
}
}
}

Changing the module settings

package com.yoctopuce.doc_examples;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;

import com.yoctopuce.YoctoAPI.YAPI;
import com.yoctopuce.YoctoAPI.YAPI_Exception;
import com.yoctopuce.YoctoAPI.YModule;

public class SaveSettings extends Activity implements OnItemSelectedListener
{

private ArrayAdapter<String> aa;
private YModule module = null;

@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.savesettings);
Spinner my_spin = (Spinner) findViewById(R.id.spinner1);
my_spin.setOnItemSelectedListener(this);
aa = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item);
aa.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
my_spin.setAdapter(aa);
}

@Override
protected void onStart()
{
super.onStart();

try {
aa.clear();
YAPI.EnableUSBHost(this);
YAPI.RegisterHub("usb");
YModule r = YModule.FirstModule();
while (r != null) {
String hwid = r.get_hardwareId();
aa.add(hwid);
r = r.nextModule();
}
} catch (YAPI_Exception e) {
e.printStackTrace();
}
// refresh Spinner with detected relay
aa.notifyDataSetChanged();
}

@Override
protected void onStop()
{
super.onStop();
YAPI.FreeAPI();
}

private void DisplayModuleInfo()
{
TextView field;
if (module == null)
return;
try {
YAPI.UpdateDeviceList();// fixme
field = (TextView) findViewById(R.id.logicalnamefield);
field.setText(module.getLogicalName());
} catch (YAPI_Exception e) {
e.printStackTrace();
}
}

@Override
public void onItemSelected(AdapterView<?> parent, View view, int pos, long id)
{
String hwid = parent.getItemAtPosition(pos).toString();
module = YModule.FindModule(hwid);
DisplayModuleInfo();
}

@Override
public void onNothingSelected(AdapterView<?> arg0)
{
}

public void saveName(View view)
{
if (module == null)
return;

EditText edit = (EditText) findViewById(R.id.newname);
String newname = edit.getText().toString();
try {
if (!YAPI.CheckLogicalName(newname)) {
Toast.makeText(getApplicationContext(), "Invalid name (" + newname + ")", Toast.LENGTH_LONG).show();
return;
}
module.set_logicalName(newname);
module.saveToFlash(); // do not forget this
edit.setText("");
} catch (YAPI_Exception ex) {
ex.printStackTrace();
}
DisplayModuleInfo();
}

}

Warning: the number of write cycles of the nonvolatile memory of the module is limited. When this limit is reached, nothing guaranties that the saving process is performed correctly. This limit, linked to the technology employed by the module micro-processor, is located at about 100000 cycles. In short, you can use the YModule.saveToFlash() function only 100000 times in the life of the module. Make sure you do not call this function within a loop.

Listing the modules

package com.yoctopuce.doc_examples;

import android.app.Activity;
import android.os.Bundle;
import android.util.TypedValue;
import android.view.View;
import android.widget.LinearLayout;
import android.widget.TextView;

import com.yoctopuce.YoctoAPI.YAPI;
import com.yoctopuce.YoctoAPI.YAPI_Exception;
import com.yoctopuce.YoctoAPI.YModule;

public class Inventory extends Activity
{

@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.inventory);
}

public void refreshInventory(View view)
{
LinearLayout layout = (LinearLayout) findViewById(R.id.inventoryList);
layout.removeAllViews();

try {
YAPI.UpdateDeviceList();
YModule module = YModule.FirstModule();
while (module != null) {
String line = module.get_serialNumber() + " (" + module.get_productName() + ")";
TextView tx = new TextView(this);
tx.setText(line);
tx.setTextSize(TypedValue.COMPLEX_UNIT_SP, 20);
layout.addView(tx);
module = module.nextModule();
}
} catch (YAPI_Exception e) {
e.printStackTrace();
}
}

@Override
protected void onStart()
{
super.onStart();
try {
YAPI.EnableUSBHost(this);
YAPI.RegisterHub("usb");
} catch (YAPI_Exception e) {
e.printStackTrace();
}
refreshInventory(null);
}

@Override
protected void onStop()
{
super.onStop();
YAPI.FreeAPI();
}

}

19.7. Error handling

In the Java API for Android, error handling is implemented with exceptions. Therefore you must catch and handle correctly all exceptions that might be thrown by the API if you do not want your software to crash soon as you unplug a device.

20. Using the Yocto-RS485 with LabVIEW

LabVIEW is edited by National Instruments since 1986. It is a graphic development environment: rather than writing lines of code, the users draw their programs, somewhat like a flow chart. LabVIEW was designed mostly to interface measuring tools, hence the Virtual Instruments name for LabVIEW programs. With visual programming, drawing complex algorithms becomes quickly fastidious. The LabVIEW Yoctopuce library was thus designed to make it as easy to use as possible. In other words, LabVIEW being an environment extremely different from other languages supported by Yoctopuce, there are major differences between the LabVIEW API and the other APIs.

20.1. Architecture

The LabVIEW library is based on the Yoctopuce DotNetProxy library contained in the DotNetProxyLibrary.dll DLL. In fact, it is this DotNetProxy library which takes care or most of the work by relying on the C# library which, in turn, uses the low level library coded in yapi.dll (32bits) and amd64\yapi.dll( 64bits).

LabVIEW Yoctopuce API architecture

You must therefore imperatively distribute the DotNetProxyLibrary.dll, yapi.dll, and amd64\yapi.dll with your LabVIEW applications using the Yoctopuce API.

If need be, you can find the low level API sources in the C# library and the DotNetProxyLibrary.dll sources in the DotNetProxy library.

20.2. Compatibility

Firmware

For the LabVIEW Yoctopuce library to work correctly with your Yoctopuce modules, these modules need to have firmware 37120, or higher.

LabVIEW for Linux and MacOS

At the time of writing, the LabVIEW Yoctopuce API has been tested under Windows only. It is therefore most likely that it simply does not work with the Linux and MacOS versions of LabVIEW.

LabVIEW NXG

The LabVIEW Yoctopuce library uses many techniques which are not yet available in the new generation of LabVIEW. The library is therefore absolutely not compatible with LabVIEW NXG.

About DotNewProxyLibrary.dll

20.3. Installation

Download the LabVIEW library from the Yoctopuce web site⁵². It is a ZIP file in which there is a distinct directory for each version of LabVIEW. Each of these directories contains two subdirectories: the first one contains programming examples for each Yoctopuce product; the second one, called VIs, contains all the VIs of the API and the required DLLs.

Depending on Windows configuration and the method used to copy the DotNetProxyLibrary.dll on your system, Windows may block it because it comes from an other computer. This may happen when the library zip file is uncompressed with Window's file explorer. If the DLL is blocked, LabVIEW will not be able to load it and an error 1386 will occur whenever any of the Yoctopuce VIs is executed.

There are two ways to fix this. The simplest is to unblock the file with the Windows file explorer: right click / properties on the DotNetProxyLibrary.dll file, and click on the unblock button. But this has to be done each time a new version of the DLL is copied on your system.

Unblock the DotNetProxyLibrary DLL.

Alternatively, one can modify the LabVIEW configuration by creating, in the same directory as the labview.exe executable, an XML file called labview.exe.config containing the following code:

<?xml version ="1.0"?>
<configuration>
<runtime>
<loadFromRemoteSources enabled="true" />
</runtime>
</configuration>

Make sure to select the correct directory depending on the LabVIEW version you are using (32 bits vs. 64 bits). You can find more information about this file on the National Instruments web site.⁵³

To install the LabVIEW Yoctopuce API, there are several methods.

Method 1 : "Take-out" installation

The simplest way to use the Yoctopuce library is to copy the content of the VIs directory wherever you want and to use the VIs in LabVIEW with a simple drag-n-drop operation.

To use the examples provided with the API, it is simpler if you add the directory of Yoctopuce VIs into the list of where LabVIEW must look for VIs that it has not found. You can access this list through the Tools > Options > Paths > VI Search Path menu.

Configuring the "VI Search Path"

Method 2 : Provided installer

In each LabVIEW folder of the Library, you will find a VI named "Install.vi", just open the one matching your LabVIEW version.

The provider installer

This installer provide 3 installation options:

Install: Keep VI and documentation files where they are.

With this option, VI files are keep in the place where the library has been unzipped. So you will have to make sure these files are not deleted as long as you need them. Here is what the installer will do if that option is chosen:

All references to Yoctopuce any library paths will be removed from the viSearchPath option in the labview.ini file.
A dir.mnu palette file referring to VIs in the install folder will be created in
C:\Program Files xx\National Instruments\LabVIEW 20xx\vi.lib\addons\Yoctopuce
A reference to the VIs source install path will inserted into the viSearchPath option in the labview.ini file.

Install: Copy VI and documentation files into LabVIEW's vi.lib folder

In that case all required files are copied inside the LabVIEW's installation folder, so you will be able to delete the installation folder once the original installation is complete. Note that programming examples won't be copied. Here is the exact behaviour of the installer in that case:

All references to Yoctopuce library paths will be removed from viSearchPath in labview.ini file
All VIs, DLLs, and documentation files will be copied into:
C:\Program Files xx\National Instruments\LabVIEW 20xx\vi.lib\Yoctopuce
VIs will be patched with the path to copied documentation files
A dir.mnu palette file referring to copied VIs will be created in
C:\Program Files xx\National Instruments\LabVIEW 20xx\vi.lib\addons\Yoctopuce

Uninstall Yoctopuce Library

this option is meant to remove the LabVIEW library from your LabVIEW installation, here is how it is done:

All references to Yoctopuce library paths will be removed from viSearchPath in labview.ini file
Following folders, if exists, will be removed:
C:\Program Files xx\National Instruments\LabVIEW 20xx\vi.lib\addons\Yoctopuce
C:\Program Files xx\National Instruments\LabVIEW 20xx\vi.lib\Yoctopuce

In any case, if the labview.ini file needs to be modified, a backup copy will be made beforehand.

The installer identifies Yoctopuce VIs library folders by checking the presence of the YRegisterHub.vi file in said folders.

Once the installation is complete, a Yoctopuce palette will appear in Functions/Addons menu.

Method 3 : Installation in a LabVIEW palette (ancillary method)

The steps to manually install the VIs directly in the LabVIEW palette are somewhat more complex. You can find the detailed procedure on the National Instruments web site ⁵⁴, but here is a summary:

Create a Yoctopuce/API directory in the C:\Program Files\National Instruments\LabVIEW xxxx\vi.lib directory and copy all the VIs and DLLs of the VIs directory into it.
Create a Yoctopuce directory in the C:\Program Files\National Instruments\LabVIEW xxxx\menus\Categories directory.
Run LabVIEW and select the option Tools>Advanced>Edit Palette Set

Three windows pop up:
- "Edit Controls and Functions Palette Set"
- "Functions"
- "Controls"
.

In the Function window, there is a Yoctopuce icon. Double-click it to create an empty "Yoctopuce" window.
In the Yoctopuce window, perform a Right click>Insert>Vi(s)..

in order to open a file chooser. Put the file chooser in the vi.lib\Yoctopuce\API directory that you have created in step 1 and click on Current Folder

All the Yoctopuce VIs now appear in the Yoctopuce window. By default, they are sorted by alphabetical order, but you can arrange them as you see fit by moving them around with the mouse. For the palette to be easy to use, we recommend to reorganize the icons over 8 columns.
In the "Edit Controls and Functions Palette Set" window, click on the "Save Changes" button, the window indicates that it has created a dir.mnu file in your Documents directory.

Copy this file in the "menus\Categories\Yoctopuce" directory that you have created in step 2.
Restart LabVIEW, the LabVIEW palette now contains a Yoctopuce sub-palette with all the VIs of the API.

20.4. Presentation of Yoctopuce VIs

The LabVIEW Yoctopuce library contains one VI per class of the Yoctopuce API, as well as a few special VIs. All the VIs have the traditional connectors Error IN and Error Out.

YRegisterHub

The YRegisterHub VI is used to initialize the API. You must imperatively call this VI once before you do anything in relation with Yoctopuce modules.

The YRegisterHub VI

The YRegisterHub VI takes a url parameter which can be:

The "usb" character string to indicated that you wish to work with local modules, directly connected by USB
An IP address to indicate that you wish to work with modules which are available through a network connection. This IP address can be that of a YoctoHub⁵⁵ or even that of a machine on which the VirtualHub⁵⁶ application is running.

In the case of an IP address, the YRegisterHub VI tries to contact this address and generates and error if it does not succeed, unless the async parameter is set to TRUE. If async is set to TRUE, no error is generated and Yoctopuce modules corresponding to that IP address become automatically available as soon as the said machine can be reached.

If everything went well, the successful output contains the value TRUE. In the opposite case, it contains the value FALSE and the error msg output contains a string of characters with a description of the error.

You can use several YRegisterHub VIs with distinct URLs if you so wish. However, on the same machine, there can be only one process accessing local Yoctopuce modules directly by USB (url set to "usb"). You can easily work around this limitation by running the VirtualHub software on the local machine and using the "127.0.0.1" url.

YFreeAPI

The YFreeAPI VI enables you to free resources allocated by the Yoctopuce API.

The YFreeAPI VI

You must call the YFreeAPI VI when your code is done with the Yoctopuce API. Otherwise, direct USB access (url set to "usb") could stay locked after the execution of your VI, and stay so for as long as LabVIEW is not completely closed.

Structure of the VIs corresponding to a class

The other VIs correspond to each function/class of the Yoctopuce API, they all have the same structure:

Structure of most VIs of the API.

Connector [11]: name must contain the hardware name or the logical name of the intended function.
Connectors [10] and [9]: input parameters depending on the nature of the VI.
Connectors [8] and [0] : error in and error out.
Connector [7] : Unique hardware name of the found function.
Connector [5] : is online contains TRUE if the function is available, FALSE otherwise.
Connectors [2] and [1]: output values depending on the nature of the VI.
Connector [6]: If this input is set to TRUE, connector [3] contains a reference to the Proxy objects implemented by the VI⁵⁷. This input is initialized to FALSE by default.
Connector [3]: Reference on the Proxy object implemented by the VI if input [6] is TRUE. This object enables you to access additional features.

You can find the list of functions available on your Yocto-RS485 in chapter Programming, general concepts.

If the desired function (parameter name) is not available, this does not generate an error, but the is online output contains FALSE and all the other outputs contain the value "N/A" whenever possible. If the desired function becomes available later in the life of your program, is online switches to TRUE automatically.

If the name parameter contains an empty string, the VI targets the first available function of the same type. If no function is available, is online is set to FALSE.

The YModule VI

The YModule VI enables you to interface with the "module" section of each Yoctopuce module. It enables you to drive the module led and to know the serial number of the module.

The YModule VI

The name input works slightly differently from other VIs. If it is called with a name parameter corresponding to a function name, the YModule VI finds the Module function of the module hosting the function. You can therefore easily find the serial number of the module of any function. This enables you to build the name of other functions which are located on the same module. The following example finds the first available YHumidity function and builds the name of the YTemperature function located on the same module. The examples provided with the Yoctopuce API make extensive use of this technique.

Using the YModule VI to retrieve functions hosted on the same module

The sensor VIs

All the VIs corresponding to Yoctopuce sensors have exactly the same geometry. Both outputs enable you to retrieve the value measured by the corresponding sensor as well the unit used.

The sensor VIs have all exactly the same geometry

The update freq input parameter is a character string enabling you to configure the way in which the output value is updated:

"auto" : The VI value is updated as soon as the sensor detects a significant modification of the value. It is the default behavior.
"x/s": The VI value is updated x times per second with the current value of the sensor.
"x/m","x/h": The VI value is updated x times per minute (resp. hour) with the average value over the latest period. Note, maximum frequencies are (60/m) and (3600/h), for higher frequencies use the (x/s) syntax.

The update frequency of the VI is a parameter managed by the physical Yoctopuce module. If several VIs try to change the frequency of the same sensor, the valid configuration is that of the latest call. It is however possible to set different update frequencies to different sensors on the same Yoctopuce module.

Changing the update frequency of the same module

The update frequency of the VI is completely independent from the sampling frequency of the sensor, which you usually cannot modify. It is useless and counterproductive to define an update frequency higher than the sensor sampling frequency.

20.5. Functioning and use of VIs

Here is one of the simplest example of VIs using the Yoctopuce API.

Minimal example of use of the LabVIEW Yoctopuce API

This example is based on the YSensor VI which is a generic VI enabling you to interface any sensor function of a Yoctopuce module. You can replace this VI by any other from the Yoctopuce API, they all have the same geometry and work in the same way. This example is limited to three actions:

It initializes the API in native ("usb") mode with the YRegisterHub VI.
It displays the value of the first Yoctopuce sensor it finds thanks to the YSensor VI.
It frees the API thanks to the YFreeAPI VI.

This example automatically looks for an available sensor. If there is such a sensor, we can retrieve its name through the hardware name output and the isOnline output equals TRUE. If there is no available sensor, the VI does not generate an error but emulates a ghost sensor which is "offline". However, if later in the life of the application, a sensor becomes available because it has been connected, isOnline switches to TRUE and the hardware name contains the name of the sensor. We can therefore easily add a few indicators in the previous example to know how the executions goes.

Use of the hardware name and isOnline outputs

The VIs of the Yoctopuce API are actually an entry door into the library. Internally, this mechanism works independently of the Yoctopuce VIs. Indeed, most communications with electronic modules are managed automatically as background tasks. Therefore, you do not necessarily need to take any specific care to use Yoctopuce VIs, you can for example use them in a non-delayed loop without creating any specific problem for the API.

The Yoctopuce VIs can be used in a non-delayed loop

Note that the YRegisterHub VI is not inside the loop. The YRegisterHub VI is used to initialize the API. Unless you have several URLs that you need to register, it is better to call the YRegisterHub VI only once.

When the name parameter is initialized to an empty string, the Yoctopuce VIs automatically look for a function they can work with. This is very handy when you know that there is only one function of the same type available and when you do not want to manage its name. If the name parameter contains a hardware name or a logical name, the VI looks for the corresponding function. If it does not find it, it emulates an offline function while it waits for the true function to become available.

Using names to identify the functions to be used

Error handling

The LabVIEW Yoctopuce API is coded to handle errors as smoothly as possible: for example, if you use a VI to access a function which does not exist, the isOnline output is set to FALSE, the other outputs are set to NaN, and thus the inputs do not have any impact. Fatal errors are propagated through the traditional error in, error out channel.

However, the YRegisterHub VI manages connection errors slightly differently. In order to make them easier to manage, connection errors are signaled with Success and error msg outputs. If there is an issue during a call to the YRegisterHub VI, Success contains FALSE and error msg contains a description of the error.

Error handling

The most common error message is "Another process is already using yAPI". It means that another application, LabVIEW or other, already uses the API in native USB mode. For technical reasons, the native USB API can be used by only one application at the same time on the same machine. You can easily work around this limitation by using the network mode.

20.6. Using Proxy objects

The Yoctopuce API contains hundreds of methods, functions, and properties. It was not possible, or desirable, to create a VI for each of them. Therefore, there is a VI per class that shows the two properties that Yoctopuce deemed the most useful, but this does not mean that the rest is not available.

Each VI corresponding to a class has two connectors create ref and optional ref which enable you to obtain a reference on the Proxy object of the .NET Proxy API on which the LabVIEW library is built.

The connectors to obtain a reference on the Proxy object corresponding to the VI

To obtain this reference, you only need to set optional ref to TRUE. Note, it is essential to close all references created in this way, otherwise you risk to quickly saturate the computer memory.

Here is an example which uses this technique to change the luminosity of the leds of a Yoctopuce module.

Regulating the luminosity of the leds of a module

Note that each reference allows you to obtain properties (property nodes) as well as methods (invoke nodes). By convention, properties are optimized to generate a minimum of communication with the modules. Therefore, we recommend to use them rather than the corresponding get_xxx and set_xxx methods which might seem equivalent but which are not optimized. Properties also enable you to retrieve the various constants of the API, prefixed with the "_" character. For technical reasons, the get_xxx and set_xxx methods are not all available as properties.

Property and Invoke nodes: Using properties, methods and constants

You can find a description of all the available properties, functions, and methods in the documentation of the .NET Proxy API.

Network mode

On a given machine, there can be only one process accessing local Yoctopuce modules directly by USB (url set to "usb"). It is however possible that multiple process connect in parallel to YoctoHubs⁵⁸ or tp a machine on which VirtualHub⁵⁹ is running, including the local machine. Therefore, if you use the local address of your machine (127.0.0.1) and if a VirtualHub runs on it, you can work around the limitation which prevents using the native USB API in parallel.

Network mode

In the same way, there is no limitation on the number of network interfaces to which the API can connect itself in parallel. This means that it is quite possible to make multiple calls to the YRegisterHub VI. This is the only case where it is useful to call the YRegisterHub VI several times in the life of the application.

You can have multiple network connections

By default, the YRegisterHub VI tries to connect itself on the address given as parameter and generates an error (success=FALSE) when it cannot do so because nobody answers. But if the async parameter is initialized to TRUE, no error is generated when the connection does not succeed. If the connection becomes possible later in the life of the application, the corresponding modules are automatically made available.

Asynchronous connection

20.7. Managing the data logger

Almost all the Yoctopuce sensors have a data logger which enables you to store the measures of the sensors in the non-volatile memory of the module. You can configure the data logger with the VirtualHub, but also with a little bit of LabVIEW code.

Logging

To do so, you must configure the logging frequency by using the "LogFrequency" property which you can reach with a reference on the Proxy object of the sensor you are using. Then, you must turn the data logger on thanks to the YDataLogger VI. Note that, like with the YModule VI, you can obtain the YDataLogger VI corresponding to a module with its own name, but also with the name of any of the functions available on the same module.

Activating the data logger

Reading

You can retrieve the data in the data logger with the YDataLoggerContents VI.

The YDataLoggerContents VI

Retrieving the data from the logger of a Yoctopuce module is a slow process which can take up to several tens of seconds. Therefore, we designed the VI enabling this operation to work iteratively.

As a first step, you must call the VI with a sensor name, a start date, and an end date (UTC UNIX timestamp). The (0,0) pair enables you to obtain the complete content of the data logger. This first call enables you to obtain a summary of the data logger content and a context.

As a second step, you must call the YDataLoggerContents VI in a loop with the context parameter, until the progress output reaches the 100 value. At this time, the data output represents the content of the data logger.

Retrieving the content of the data logger

The results and the summary are returned as an array of structures containing the following fields:

startTime: beginning of the measuring period
endTime: end of the measuring period
averageValue: average value for the period
minValue: minimum value over the period
maxValue: maximum value over the period

Note that if the logging frequency is superior to 1Hz, the data logger stores only current values. In this case, averageValue, minValue, and maxValue share the same value.

20.8. Function list

Each VI corresponding to an object of the Proxy API enables you to list all the functions of the same class with the getSimilarfunctions() method of the corresponding Proxy object. Thus, you can easily perform an inventory of all the connected modules, of all the connected sensors, of all the connected relays, and so on.

Retrieving the list of all the modules which are connected

20.9. A word on performances

The LabVIEW Yoctopuce API is optimized so that all the VIs and .NET Proxy API object properties generate a minimum of communication with Yoctopuce modules. Thus, you can use them in loops without taking any specific precaution: you do not have to slow down the loops with a timer.

These two loops generate little USB communication and do not need to be slowed down

However, almost all the methods of the available Proxy objects initiate a communication with the Yoctopuce modules each time they are called. You should therefore avoid calling them too often without purpose.

This loop, using a method, must be slowed down

20.10. A full example of a LabVIEW program

Here is an example showing how to interface a ZELIO REG48PUN1RHU controller with a Yocto-RS485 in LabView. After a call to the YRegisterHub VI, the YSerialPort VI finds the first serial port available, then gets a reference on the matching YSerialPortProxy object. If the serial port is "online" then the application reads the PS and SV registers thanks to the ModbusWriteRegister method. Each click on the "+" / "-" button will increment / decrement the SV value and update the controller accordingly with a call to the ModbusWriteRegister method. When the application is about to close, the YSerialPortProxy object reference is closed and the Yoctopuce API is freed with the YFreeAPI VI.

Interfacing a ZELIO REG48PUN1RHU controller with a Yocto-RS485 in LabVIEW.

If you read this documentation on screen, you can zoom on the image above. You can also find this example in the LabVIEW Yoctopuce library.

20.11. Differences from other Yoctopuce APIs

Yoctopuce does everything it can to maintain a strong coherence between its different programming libraries. However, LabVIEW being clearly apart as an environment, there are, as a consequence, important differences from the other libraries.

These differences were introduced to make the use of modules as easy as possible and requiring a minimum of LabVIEW code.

YFreeAPI

In the opposite to other languages, you must absolutely free the native API by calling the YFreeAPI VI when your code does not need to use the API anymore. If you forget this call, the native API risks to stay locked for the other applications until LabVIEW is completely closed.

Properties

In the opposite to classes of the other APIs, classes available in LabVIEW implement properties. By convention, these properties are optimized to generate a minimum of communication with the modules while automatically refreshing. By contrast, methods of type get_xxx and set_xxx systematically generate communications with the Yoctopuce modules and must be called sparingly.

Callback vs. Properties

There is no callback in the LabVIEW Yoctopuce API, the VIs automatically refresh: they are based on the properties of the .NET Proxy API objects.

21. Using with unsupported languages

Yoctopuce modules can be driven from most common programming languages. New languages are regularly added, depending on the interest expressed by Yoctopuce product users. Nevertheless, some languages are not, and will never be, supported by Yoctopuce. There can be several reasons for this: compilers which are not available anymore, unadapted environments, etc.

However, there are alternative methods to access Yoctopuce modules from an unsupported programming language.

21.1. Command line

The easiest method to drive Yoctopuce modules from an unsupported programming language is to use the command line API through system calls. The command line API is in fact made of a group of small executables which are easy to call. Their output is also easy to analyze. As most programming languages allow you to make system calls, the issue is solved with a few lines of code.

However, if the command line API is the easiest solution, it is neither the fastest nor the most efficient. For each call, the executable must initialize its own API and make an inventory of USB connected modules. This requires about one second per call.

21.2. .NET Assembly

A .NET Assembly enables you to share a set of pre-compiled classes to offer a service, by stating entry points which can be used by third-party applications. In our case, it's the whole Yoctopuce library which is available in the .NET Assembly, so that it can be used in any environment which supports .NET Assembly dynamic loading.

The Yoctopuce library as a .NET Assembly does not contain only the standard C# Yoctopuce library, as this wouldn't have allowed an optimal use in all environments. Indeed, we cannot expect host applications to necessarily offer a thread system or a callback system, although they are very useful to manage plug-and-play events and sensors with a high refresh rate. Likewise, we can't expect from external applications a transparent behavior in cases where a function call in Assembly creates a delay because of network communications.

Therefore, we added to it an additional layer, called .NET Proxy library. This additional layer offers an interface very similar to the standard library but somewhat simplified, as it internally manages all the callback mechanisms. Instead, this library offers mirror objects, called Proxys, which publish through Properties the main attributes of the Yoctopuce functions such as the current measure, configuration parameters, the state, and so on.

.NET Assembly Architecture

The callback mechanism automatically updates the properties of the Proxys objects, without the host application needing to care for it. The later can thus, at any time and without any risk of latency, display the value of all properties of Yoctopuce Proxy objects.

Pay attention to the fact that the yapi.dll low-level communication library is not included in the .NET Assembly. You must therefore keep it together with DotNetProxyLibrary.dll. The 32 bit version must be located in the same directory as DotNetProxyLibrary.dll, while the 64 bit version must be in a subdirectory amd64.

Example of use with MATLAB

Here is how to load our Proxy .NET Assembly in MATLAB and how to read the value of the first sensor connected by USB found on the machine:

NET.addAssembly("C:/Yoctopuce/DotNetProxyLibrary.dll");
import YoctoProxyAPI.*

errmsg = YAPIProxy.RegisterHub("usb");
sensor = YSensorProxy.FindSensor("");
measure = sprintf('%.3f %s', sensor.CurrentValue, sensor.Unit);

Example of use in PowerShell

PowerShell commands are a little stranger, but we can recognize the same structure:

Add-Type -Path "C:/Yoctopuce/DotNetProxyLibrary.dll"

$errmsg = [YoctoProxyAPI.YAPIProxy]::RegisterHub("usb")
$sensor = [YoctoProxyAPI.YSensorProxy]::FindSensor("")
$measure = "{0:n3} {1}" -f $sensor.CurrentValue, $sensor.Unit

Specificities of the .NET Proxy library

With regards to classic Yoctopuce libraries, the following differences in particular should be noted:

No FirstModule/nextModule method

To obtain an object referring to the first found module, we call YModuleProxy.FindModule(""). If there is no connected module, this method returns an object with its module.IsOnline property set to False. As soon as a module is connected, the property changes to True and the module hardware identifier is updated.

To list modules, you can call the module.GetSimilarFunctions() method which returns an array of character strings containing the identifiers of all the modules which were found.

No callback function

Callback functions are implemented internally and they update the object properties. You can therefore simply poll the properties, without significant performance penalties. Be aware that if you use one of the function that disables callbacks, the automatic refresh of object properties may not work anymore.

A new method YAPIProxy.GetLog makes it possible to retrieve low-level debug logs without using callbacks.

Enumerated types

In order to maximize compatibility with host applications, the .NET Proxy library does not use true .NET enumerated types, but simple integers. For each enumerated type, the library includes public constants named according to the possible values. Contrarily to standard Yoctopuce libraries, numeric values always start from 1, as the value 0 is reserved to return an invalid value, for instance when the device is disconnected.

Invalid numeric results

For all numeric results, rather than using an arbitrary constant, the invalid value returned in case of error is NaN. You should therefore use function isNaN() to detect this value.

Using .NET Assembly without the Proxy library

If for a reason or another you don't want to use the Proxy library, and if your environment allows it, you can use the standard C# API as it is located in the Assembly, under the YoctoLib namespace. Beware however not to mix both types of use: either you go through the Proxy library, or you use he YoctoLib version directly, but not both!

CompatibilitÃ©

For the LabVIEW Yoctopuce library to work correctly with your Yoctopuce modules, these modules need to have firmware 37120, or higher.

In order to be compatible with as many versions of Windows as possible, including Windows XP, the DotNetProxyLibrary.dll library is compiled in .NET 3.5, which is available by default on all the Windows versions since XP. As of today, we have never met any non-Windows environment able to load a .NET Assembly, so we only ship the low-level communication dll for Windows together with the assembly.

21.3. VirtualHub and HTTP GET

The VirtualHub is available on almost all current platforms. It is generally used as a gateway to provide access to Yoctopuce modules from languages which prevent direct access to hardware layers of a computer (JavaScript, PHP, Java, ...).

In fact, the VirtualHub is a small web server able to route HTTP requests to Yoctopuce modules. This means that if you can make an HTTP request from your programming language, you can drive Yoctopuce modules, even if this language is not officially supported.

REST interface

At a low level, the modules are driven through a REST API. Thus, to control a module, you only need to perform appropriate requests on the VirtualHub. By default, the VirtualHub HTTP port is 4444.

An important advantage of this technique is that preliminary tests are very easy to implement. You only need a VirtualHub and a simple web browser. If you copy the following URL in your preferred browser, while the VirtualHub is running, you obtain the list of the connected modules.

http://127.0.0.1:4444/api/services/whitePages.txt

Note that the result is displayed as text, but if you request whitePages.xml, you obtain an XML result. Likewise, whitePages.json allows you to obtain a JSON result. The html extension even allows you to display a rough interface where you can modify values in real time. The whole REST API is available in these different formats.

Driving a module through the REST interface

Each Yoctopuce module has its own REST interface, available in several variants. Let us imagine a Yocto-RS485 with the RS485MK1-12345 serial number and the myModule logical name. The following URL allows you to know the state of the module.

http://127.0.0.1:4444/bySerial/RS485MK1-12345/api/module.txt

You can naturally also use the module logical name rather than its serial number.

http://127.0.0.1:4444/byName/myModule/api/module.txt

To retrieve the value of a module property, simply add the name of the property below module. For example, if you want to know the signposting led luminosity, send the following request:

http://127.0.0.1:4444/bySerial/RS485MK1-12345/api/module/luminosity

To change the value of a property, modify the corresponding attribute. Thus, to modify the luminosity, send the following request:

http://127.0.0.1:4444/bySerial/RS485MK1-12345/api/module?luminosity=100

Driving the module functions through the REST interface

The module functions can be manipulated in the same way. To know the state of the serialPort function, build the following URL:

http://127.0.0.1:4444/bySerial/RS485MK1-12345/api/serialPort.txt

Note that if you can use logical names for the modules instead of their serial number, you cannot use logical names for functions. Only hardware names are authorized to access functions.

You can retrieve a module function attribute in a way rather similar to that used with the modules. For example:

http://127.0.0.1:4444/bySerial/RS485MK1-12345/api/serialPort/logicalName

Rather logically, attributes can be modified in the same manner.

http://127.0.0.1:4444/bySerial/RS485MK1-12345/api/serialPort?logicalName=myFunction

You can find the list of available attributes for your Yocto-RS485 at the beginning of the Programming chapter.

Accessing Yoctopuce data logger through the REST interface

This section only applies to devices with a built-in data logger.

The preview of all recorded data streams can be retrieved in JSON format using the following URL:

http://127.0.0.1:4444/bySerial/RS485MK1-12345/dataLogger.json

Individual measures for any given stream can be obtained by appending the desired function identifier as well as start time of the stream:

http://127.0.0.1:4444/bySerial/RS485MK1-12345/dataLogger.json?id=serialPort&utc=1389801080

21.4. Using dynamic libraries

The low level Yoctopuce API is available under several formats of dynamic libraries written in C. The sources are available with the C++ API. If you use one of these low level libraries, you do not need the VirtualHub anymore.

Filename	Platform
libyapi.dylib	Max OS X
libyapi-amd64.so	Linux Intel (64 bits)
libyapi-armel.so	Linux ARM EL (32 bits)
libyapi-armhf.so	Linux ARM HL (32 bits)
libyapi-aarch64.so	Linux ARM (64 bits)
libyapi-i386.so	Linux Intel (32 bits)
yapi64.dll	Windows (64 bits)
yapi.dll	Windows (32 bits)

These dynamic libraries contain all the functions necessary to completely rebuild the whole high level API in any language able to integrate these libraries. This chapter nevertheless restrains itself to describing basic use of the modules.

Driving a module

The three essential functions of the low level API are the following:

int yapiInitAPI(int connection_type, char *errmsg);
int yapiUpdateDeviceList(int forceupdate, char *errmsg);
int yapiHTTPRequest(char *device, char *request, char* buffer,int buffsize,int *fullsize, char *errmsg);

The yapiInitAPI function initializes the API and must be called once at the beginning of the program. For a USB type connection, the connection_type parameter takes value 1. The errmsg parameter must point to a 255 character buffer to retrieve a potential error message. This pointer can also point to null. The function returns a negative integer in case of error, zero otherwise.

The yapiUpdateDeviceList manages the inventory of connected Yoctopuce modules. It must be called at least once. To manage hot plug and detect potential newly connected modules, this function must be called at regular intervals. The forceupdate parameter must take value 1 to force a hardware scan. The errmsg parameter must point to a 255 character buffer to retrieve a potential error message. This pointer can also point to null. The function returns a negative integer in case of error, zero otherwise.

Finally, the yapiHTTPRequest function sends HTTP requests to the module REST API. The device parameter contains the serial number or the logical name of the module which you want to reach. The request parameter contains the full HTTP request (including terminal line breaks). buffer points to a character buffer long enough to contain the answer. buffsize is the size of the buffer. fullsize is a pointer to an integer to which will be assigned the actual size of the answer. The errmsg parameter must point to a 255 character buffer to retrieve a potential error message. This pointer can also point to null. The function returns a negative integer in case of error, zero otherwise.

The format of the requests is the same as the one described in the VirtualHub et HTTP GET section. All the character strings used by the API are strings made of 8-bit characters: Unicode and UTF8 are not supported.

The resutlt returned in the buffer variable respects the HTTP protocol. It therefore includes an HTTP header. This header ends with two empty lines, that is a sequence of four ASCII characters 13, 10, 13, 10.

Here is a sample program written in pascal using the yapi.dll DLL to read and then update the luminosity of a module.

// Dll functions import
function yapiInitAPI(mode:integer;
errmsg : pansichar):integer;cdecl;
external 'yapi.dll' name 'yapiInitAPI';
function yapiUpdateDeviceList(force:integer;errmsg : pansichar):integer;cdecl;
external 'yapi.dll' name 'yapiUpdateDeviceList';
function yapiHTTPRequest(device:pansichar;url:pansichar; buffer:pansichar;
buffsize:integer;var fullsize:integer;
errmsg : pansichar):integer;cdecl;
external 'yapi.dll' name 'yapiHTTPRequest';

var
errmsgBuffer : array [0..256] of ansichar;
dataBuffer : array [0..1024] of ansichar;
errmsg,data : pansichar;
fullsize,p : integer;

const
serial = 'RS485MK1-12345';
getValue = 'GET /api/module/luminosity HTTP/1.1'#13#10#13#10;
setValue = 'GET /api/module?luminosity=100 HTTP/1.1'#13#10#13#10;

begin
errmsg := @errmsgBuffer;
data := @dataBuffer;
// API initialization
if(yapiInitAPI(1,errmsg)<0) then
begin
writeln(errmsg);
halt;
end;

// forces a device inventory
if( yapiUpdateDeviceList(1,errmsg)<0) then
begin
writeln(errmsg);
halt;
end;

// requests the module luminosity
if (yapiHTTPRequest(serial,getValue,data,sizeof(dataBuffer),fullsize,errmsg)<0) then
begin
writeln(errmsg);
halt;
end;

// searches for the HTTP header end
p := pos(#13#10#13#10,data);

// displays the response minus the HTTP header
writeln(copy(data,p+4,length(data)-p-3));

// changes the luminosity
if (yapiHTTPRequest(serial,setValue,data,sizeof(dataBuffer),fullsize,errmsg)<0) then
begin
writeln(errmsg);
halt;
end;

end.

Module inventory

To perform an inventory of Yoctopuce modules, you need two functions from the dynamic library:

int yapiGetAllDevices(int *buffer,int maxsize,int *neededsize,char *errmsg);
int yapiGetDeviceInfo(int devdesc,yDeviceSt *infos, char *errmsg);

The yapiGetAllDevices function retrieves the list of all connected modules as a list of handles. buffer points to a 32-bit integer array which contains the returned handles. maxsize is the size in bytes of the buffer. To neededsize is assigned the necessary size to store all the handles. From this, you can deduce either the number of connected modules or that the input buffer is too small. The errmsg parameter must point to a 255 character buffer to retrieve a potential error message. This pointer can also point to null. The function returns a negative integer in case of error, zero otherwise.

The yapiGetDeviceInfo function retrieves the information related to a module from its handle. devdesc is a 32-bit integer representing the module and which was obtained through yapiGetAllDevices. infos points to a data structure in which the result is stored. This data structure has the following format:

Name	Type	Size (bytes)	Description
vendorid	int	4	Yoctopuce USB ID
deviceid	int	4	Module USB ID
devrelease	int	4	Module version
nbinbterfaces	int	4	Number of USB interfaces used by the module
manufacturer	char[]	20	Yoctopuce (null terminated)
productname	char[]	28	Model (null terminated)
serial	char[]	20	Serial number (null terminated)
logicalname	char[]	20	Logical name (null terminated)
firmware	char[]	22	Firmware version (null terminated)
beacon	byte	1	Beacon state (0/1)

The errmsg parameter must point to a 255 character buffer to retrieve a potential error message.

Here is a sample program written in pascal using the yapi.dll DLL to list the connected modules.

// device description structure
type yDeviceSt = packed record
vendorid : word;
deviceid : word;
devrelease : word;
nbinbterfaces : word;
manufacturer : array [0..19] of ansichar;
productname : array [0..27] of ansichar;
serial : array [0..19] of ansichar;
logicalname : array [0..19] of ansichar;
firmware : array [0..21] of ansichar;
beacon : byte;
end;

// Dll function import
function yapiInitAPI(mode:integer;
errmsg : pansichar):integer;cdecl;
external 'yapi.dll' name 'yapiInitAPI';

function yapiUpdateDeviceList(force:integer;errmsg : pansichar):integer;cdecl;
external 'yapi.dll' name 'yapiUpdateDeviceList';

function yapiGetAllDevices( buffer:pointer;
maxsize:integer;
var neededsize:integer;
errmsg : pansichar):integer; cdecl;
external 'yapi.dll' name 'yapiGetAllDevices';

function apiGetDeviceInfo(d:integer; var infos:yDeviceSt;
errmsg : pansichar):integer; cdecl;
external 'yapi.dll' name 'yapiGetDeviceInfo';

var
errmsgBuffer : array [0..256] of ansichar;
dataBuffer : array [0..127] of integer; // max of 128 USB devices
errmsg,data : pansichar;
neededsize,i : integer;
devinfos : yDeviceSt;

begin
errmsg := @errmsgBuffer;

// API initialization
if(yapiInitAPI(1,errmsg)<0) then
begin
writeln(errmsg);
halt;
end;

// forces a device inventory
if( yapiUpdateDeviceList(1,errmsg)<0) then
begin
writeln(errmsg);
halt;
end;

// loads all device handles into dataBuffer
if yapiGetAllDevices(@dataBuffer,sizeof(dataBuffer),neededsize,errmsg)<0 then
begin
writeln(errmsg);
halt;
end;

// gets device info from each handle
for i:=0 to neededsize div sizeof(integer)-1 do
begin
if (apiGetDeviceInfo(dataBuffer[i], devinfos, errmsg)<0) then
begin
writeln(errmsg);
halt;
end;
writeln(pansichar(@devinfos.serial)+' ('+pansichar(@devinfos.productname)+')');
end;

end.

VB6 and yapi.dll

Each entry point from the yapi.dll is duplicated. You will find one regular C-decl version and one Visual Basic 6 compatible version, prefixed with vb6_.

21.5. Porting the high level library

As all the sources of the Yoctopuce API are fully provided, you can very well port the whole API in the language of your choice. Note, however, that a large portion of the API source code is automatically generated.

Therefore, it is not necessary for you to port the complete API. You only need to port the yocto_api file and one file corresponding to a function, for example yocto_relay. After a little additional work, Yoctopuce is then able to generate all other files. Therefore, we highly recommend that you contact Yoctopuce support before undertaking to port the Yoctopuce library in another language. Collaborative work is advantageous to both parties.

22. Advanced programming

The preceding chapters have introduced, in each available language, the basic programming functions which can be used with your Yocto-RS485 module. This chapter presents in a more generic manner a more advanced use of your module. Examples are provided in the language which is the most popular among Yoctopuce customers, that is C#. Nevertheless, you can find complete examples illustrating the concepts presented here in the programming libraries of each language.

To remain as concise as possible, examples provided in this chapter do not perform any error handling. Do not copy them "as is" in a production application.

22.1. Event programming

The methods to manage Yoctopuce modules which we presented to you in preceding chapters were polling functions, consisting in permanently asking the API if something had changed. While easy to understand, this programming technique is not the most efficient, nor the most reactive. Therefore, the Yoctopuce programming API also provides an event programming model. This technique consists in asking the API to signal by itself the important changes as soon as they are detected. Each time a key parameter is modified, the API calls a callback function which you have defined in advance.

Detecting module arrival and departure

Hot-plug management is important when you work with USB modules because, sooner or later, you will have to connect or disconnect a module when your application is running. The API is designed to manage module unexpected arrival or departure in a transparent way. But your application must take this into account if it wants to avoid pretending to use a disconnected module.

Event programming is particularly useful to detect module connection/disconnection. Indeed, it is simpler to be told of new connections rather than to have to permanently list the connected modules to deduce which ones just arrived and which ones left. To be warned as soon as a module is connected, you need three pieces of code.

The callback

The callback is the function which is called each time a new Yoctopuce module is connected. It takes as parameter the relevant module.

static void deviceArrival(YModule m)
{
Console.WriteLine("New module : " + m.get_serialNumber());
}

Initialization

You must then tell the API that it must call the callback when a new module is connected.

YAPI.RegisterDeviceArrivalCallback(deviceArrival);

Note that if modules are already connected when the callback is registered, the callback is called for each of the already connected modules.

Triggering callbacks

A classis issue of callback programming is that these callbacks can be triggered at any time, including at times when the main program is not ready to receive them. This can have undesired side effects, such as dead-locks and other race conditions. Therefore, in the Yoctopuce API, module arrival/departure callbacks are called only when the UpdateDeviceList() function is running. You only need to call UpdateDeviceList() at regular intervals from a timer or from a specific thread to precisely control when the calls to these callbacks happen:

// waiting loop managing callbacks
while (true)
{
// module arrival / departure callback
YAPI.UpdateDeviceList(ref errmsg);
// non active waiting time managing other callbacks
YAPI.Sleep(500, ref errmsg);
}

In a similar way, it is possible to have a callback when a module is disconnected. You can find a complete example implemented in your favorite programming language in the Examples/Prog-EventBased directory of the corresponding library.

Be aware that in most programming languages, callbacks must be global procedures, and not methods. If you wish for the callback to call the method of an object, define your callback as a global procedure which then calls your method.

Detecting a modification in the value of a sensor

The Yoctopuce API also provides a callback system allowing you to be notified automatically with the value of any sensor, either when the value has changed in a significant way or periodically at a preset frequency. The code necessary to do so is rather similar to the code used to detect when a new module has been connected.

This technique is useful in particular if you want to detect very quick value changes (within a few milliseconds), as it is much more efficient than reading repeatedly the sensor value and therefore gives better performances.

Calliback invocation

To enable a better control, value change callbacks are only called when the YAPI.Sleep() and YAPI.HandleEvents() functions are running. Therefore, you must call one of these functions at a regular interval, either from a timer or from a parallel thread.

while (true)
{
// inactive waiting loop allowing you to trigger
// value change callbacks
YAPI.Sleep(500, ref errmsg);
}

In programming environments where only the interface thread is allowed to interact with the user, it is often appropriate to call YAPI.HandleEvents() from this thread.

The value change callback

This type of callback is called when a generic sensor changes in a significant way. It takes as parameter the relevant function and the new value, as a character string. ⁶⁰

static void valueChangeCallback(YGenericSensor fct, string value)
{
Console.WriteLine(fct.get_hardwareId() + "=" + value);
}

In most programming languages, callbacks are global procedures, not methods. If you wish for the callback to call a method of an object, define your callback as a global procedure which then calls your method. If you need to keep a reference to your object, you can store it directly in the YGenericSensor object using function set_userData. You can then retrieve it in the global callback procedure using get_userData.

Setting up a value change callback

The callback is set up for a given GenericSensor function with the help of the registerValueCallback method. The following example sets up a callback for the first available GenericSensor function.

YGenericSensor f = YGenericSensor.FirstGenericSensor();
f.registerValueCallback(genericSensor1ChangeCallBack)

Note that each module function can thus have its own distinct callback. By the way, if you like to work with value change callbacks, you will appreciate the fact that value change callbacks are not limited to sensors, but are also available for all Yoctopuce devices (for instance, you can also receive a callback any time a relay state changes).

The timed report callback

This type of callback is automatically called at a predefined time interval. The callback frequency can be configured individually for each sensor, with frequencies going from hundred calls per seconds down to one call per hour. The callback takes as parameter the relevant function and the measured value, as an YMeasure object. Contrarily to the value change callback that only receives the latest value, an YMeasure object provides both minimal, maximal and average values since the timed report callback. Moreover, the measure includes precise timestamps, which makes it possible to use timed reports for a time-based graph even when not handled immediately.

static void periodicCallback(YGenericSensor fct, YMeasure measure)
{
Console.WriteLine(fct.get_hardwareId() + "=" +
measure.get_averageValue());
}

Setting up a timed report callback

The callback is set up for a given GenericSensor function with the help of the registerTimedReportCallback method. The callback will only be invoked once a callback frequency as been set using set_reportFrequency (which defaults to timed report callback turned off). The frequency is specified as a string (same as for the data logger), by specifying the number of calls per second (/s), per minute (/m) or per hour (/h). The maximal frequency is 100 times per second (i.e. "100/s"), and the minimal frequency is 1 time per hour (i.e. "1/h"). When the frequency is higher than or equal to 1/s, the measure represents an instant value. When the frequency is below, the measure will include distinct minimal, maximal and average values based on a sampling performed automatically by the device.

The following example sets up a timed report callback 4 times per minute for t he first available GenericSensor function.

YGenericSensor f = YGenericSensor.FirstGenericSensor();
f.set_reportFrequency("4/m");
f.registerTimedReportCallback(periodicCallback);

As for value change callbacks, each module function can thus have its own distinct timed report callback.

Generic callback functions

It is sometimes desirable to use the same callback function for various types of sensors (e.g. for a generic sensor graphing application). This is possible by defining the callback for an object of class YSensor rather than YGenericSensor. Thus, the same callback function will be usable with any subclass of YSensor (and in particular with YGenericSensor). With the callback function, you can use the method get_unt() to get the physical unit of the sensor, if you need to display it.

A complete example

You can find a complete example implemented in your favorite programming language in the Examples/Prog-EventBased directory of the corresponding library.

22.2. The data logger

Your Yocto-RS485 is equipped with a data logger able to store non-stop the measures performed by the module. The maximal frequency is 100 times per second (i.e. "100/s"), and the minimal frequency is 1 time per hour (i.e. "1/h"). When the frequency is higher than or equal to 1/s, the measure represents an instant value. When the frequency is below, the measure will include distinct minimal, maximal and average values based on a sampling performed automatically by the device.

Note that is useless and counter-productive to set a recording frequency higher than the native sampling frequency of the recorded sensor.

The data logger flash memory can store about 500'000 instant measures, or 125'000 averaged measures. When the memory is about to be saturated, the oldest measures are automatically erased.

Make sure not to leave the data logger running at high speed unless really needed: the flash memory can only stand a limited number of erase cycles (typically 100'000 cycles). When running at full speed, the datalogger can burn more than 100 cycles per day ! Also be aware that it is useless to record measures at a frequency higher than the refresh frequency of the physical sensor itself.

Starting/stopping the datalogger

The data logger can be started with the set_recording() method.

YDataLogger l = YDataLogger.FirstDataLogger();
l.set_recording(YDataLogger.RECORDING_ON);

It is possible to make the data recording start automatically as soon as the module is powered on.

YDataLogger l = YDataLogger.FirstDataLogger();
l.set_autoStart(YDataLogger.AUTOSTART_ON);
l.get_module().saveToFlash(); // do not forget to save the setting

Note: Yoctopuce modules do not need an active USB connection to work: they start working as soon as they are powered on. The Yocto-RS485 can store data without necessarily being connected to a computer: you only need to activate the automatic start of the data logger and to power on the module with a simple USB charger.

Erasing the memory

The memory of the data logger can be erased with the forgetAllDataStreams() function. Be aware that erasing cannot be undone.

YDataLogger l = YDataLogger.FirstDataLogger();
l.forgetAllDataStreams();

Choosing the logging frequency

The logging frequency can be set up individually for each sensor, using the method set_logFrequency(). The frequency is specified as a string (same as for timed report callbacks), by specifying the number of calls per second (/s), per minute (/m) or per hour (/h). The default value is "1/s".

The following example configures the logging frequency at 15 measures per minute for the first sensor found, whatever its type:

YSensor sensor = YSensor.FirstSensor();
sensor.set_logFrequency("15/m");

To avoid wasting flash memory, it is possible to disable logging for specified functions. In order to do so, simply use the value "OFF":

sensor.set_logFrequency("OFF");

Limitation: The Yocto-RS485 cannot use a different frequency for timed-report callbacks and for recording data into the datalogger. You can disable either of them individually, but if you enable both timed-report callbacks and logging for a given function, the two will work at the same frequency.

Retrieving the data

To load recorded measures from the Yocto-RS485 flash memory, you must call the get_recordedData() method of the desired sensor, and specify the time interval for which you want to retrieve measures. The time interval is given by the start and stop UNIX timestamp. You can also specify 0 if you don't want any start or stop limit.

The get_recordedData() method does not return directly am array of measured values, since in some cases it would cause a huge load that could affect the responsiveness of the application. Instead, this function will return an YDataSet object that can be used to retrieve immediately an overview of the measured data (summary), and then to load progressively the details when desired.

Here are the main methods used to retrieve recorded measures:

dataset = sensor.get_recordedData(0,0): select the desired time interval
dataset.loadMore(): load data from the device, progressively
dataset.get_summary(): get a single measure summarizing the full time interval
dataset.get_preview(): get an array of measures representing a condensed version of the whole set of measures on the selected time interval (reduced by a factor of approx. 200)
dataset.get_measures(): get an array with all detailled measures (that grows while loadMore is being called repeteadly)

Measures are instances of YMeasure ⁶¹. They store simultaneously the minimal, average and maximal value at a given time, that you can retrieve using methods get_minValue(), get_averageValue() and get_maxValue() respectively. Here is a small example that uses the functions above:

// We will retrieve all measures, without time limit
YDataSet dataset = sensor.get_recordedData(0, 0);

// First call to loadMore() loads the summary/preview
dataset.loadMore();
YMeasure summary = dataset.get_summary();
string timeFmt = "dd MMM yyyy hh:mm:ss,fff";
string logFmt = "from {0} to {1} : average={2:0.00}{3}";
Console.WriteLine(String.Format(logFmt,
summary.get_startTimeUTC_asDateTime().ToString(timeFmt),
summary.get_endTimeUTC_asDateTime().ToString(timeFmt),
summary.get_averageValue(), sensor.get_unit()));

// Next calls to loadMore() will retrieve measures
Console.WriteLine("loading details");
int progress;
do {
Console.Write(".");
progress = dataset.loadMore();
} while(progress < 100);

// All measures have now been loaded
List<YMeasure> details = dataset.get_measures();
foreach (YMeasure m in details) {
Console.WriteLine(String.Format(logFmt,
m.get_startTimeUTC_asDateTime().ToString(timeFmt),
m.get_endTimeUTC_asDateTime().ToString(timeFmt),
m.get_averageValue(), sensor.get_unit()));
}

You will find a complete example demonstrating how to retrieve data from the logger for each programming language directly in the Yoctopuce library. The example can be found in directory Examples/Prog-DataLogger.

Timestamp

As the Yocto-RS485 does not have a battery, it cannot guess alone the current time when powered on. Nevertheless, the Yocto-RS485 will automatically try to adjust its real-time reference using the host to which it is connected, in order to properly attach a timestamp to each measure in the datalogger:

When the Yocto-RS485 is connected to a computer running either the VirtualHub or any application using the Yoctopuce library, it will automatically receive the time from this computer.
When the Yocto-RS485 is connected to a YoctoHub-Ethernet, it will get the time that the YoctoHub has obtained from the network (using a server from pool.ntp.org)
When the Yocto-RS485 is connected to a YoctoHub-Wireless, it will get the time provided by the YoctoHub based on its internal battery-powered real-time clock, which was itself configured either from the network or from a computer
When the Yocto-RS485 is connected to an Android mobile device, it will get the time from the mobile device as long as an app using the Yoctopuce library is launched.

When none of these conditions applies (for instance if the module is simply connected to an USB charger), the Yocto-RS485 will do its best effort to attach a reasonable timestamp to the measures, using the timestamp found on the latest recorded measures. It is therefore possible to "preset to the real time" an autonomous Yocto-RS485 by connecting it to an Android mobile phone, starting the data logger, then connecting the device alone on an USB charger. Nevertheless, be aware that without external time source, the internal clock of the Yocto-RS485 might be be subject to a clock skew (theoretically up to 2%).

22.3. Sensor calibration

Your Yocto-RS485 module is equipped with a digital sensor calibrated at the factory. The values it returns are supposed to be reasonably correct in most cases. There are, however, situations where external conditions can impact the measures.

The Yoctopuce API provides the mean to re-caliber the values measured by your Yocto-RS485. You are not going to modify the hardware settings of the module, but rather to transform afterwards the measures taken by the sensor. This transformation is controlled by parameters stored in the flash memory of the module, making it specific for each module. This re-calibration is therefore a fully software matter and remains perfectly reversible.

Before deciding to re-calibrate your Yocto-RS485 module, make sure you have well understood the phenomena which impact the measures of your module, and that the differences between true values and measured values do not result from a incorrect use or an inadequate location of the module.

The Yoctopuce modules support two types of calibration. On the one hand, a linear interpolation based on 1 to 5 reference points, which can be performed directly inside the Yocto-RS485. On the other hand, the API supports an external arbitrary calibration, implemented with callbacks.

1 to 5 point linear interpolation

These transformations are performed directly inside the Yocto-RS485 which means that you only have to store the calibration points in the module flash memory, and all the correction computations are done in a perfectly transparent manner: The function get_currentValue() returns the corrected value while the function get_currentRawValue() keeps returning the value before the correction.

Calibration points are simply (Raw_value, Corrected_value) couples. Let us look at the impact of the number of calibration points on the corrections.

1 point correction

The 1 point correction only adds a shift to the measures. For example, if you provide the calibration point (a, b), all the measured values are corrected by adding to them b-a, so that when the value read on the sensor is a, the genericSensor1 function returns b.

Measure correction with 1 calibration point, here (5,10)

The application is very simple: you only need to call the calibrateFromPoints() method of the function you wish to correct. The following code applies the correction illustrated on the graph above to the first genericSensor1 function found. Note the call to the saveToFlash method of the module hosting the function, so that the module does not forget the calibration as soon as it is disconnected.

Double[] ValuesBefore = {5};
Double[] ValuesAfter = {10};
YGenericSensor f = YGenericSensor.FirstGenericSensor();
f.calibrateFromPoints(ValuesBefore, ValuesAfter);
f.get_module().saveToFlash();

2 point correction

2 point correction allows you to perform both a shift and a multiplication by a given factor between two points. If you provide the two points (a, b) and (c, d), the function result is multiplied (d-b)/(c-a) in the [a, c] range and shifted, so that when the value read by the sensor is a or c, the genericSensor1 function returns respectively b and d. Outside of the [a, c] range, the values are simply shifted, so as to preserve the continuity of the measures: an increase of 1 on the value read by the sensor induces an increase of 1 on the returned value.

Measure correction with the two calibration points (10,5) and (25,10).

The code allowing you to program this calibration is very similar to the preceding code example.

Double[] ValuesBefore = {10,25};
Double[] ValuesAfter = {5,10};
YGenericSensor f = YGenericSensor.FirstGenericSensor();
f.calibrateFromPoints(ValuesBefore, ValuesAfter);
f.get_module().saveToFlash();

Note that the values before correction must be sorted in a strictly ascending order, otherwise they are simply ignored.

3 to 5 point correction

3 to 5 point corrections are only a generalization of the 2 point method, allowing you to create up to 4 correction ranges for an increased precision. These ranges cannot be disjoint.

Correction example with 3 calibration points

Back to normal

To cancel the effect of a calibration on a function, call the calibrateFromPoints() method with two empty arrays.

Double[] ValuesBefore = {};
Double[] ValuesAfter = {};
YGenericSensor f = YGenericSensor.FirstGenericSensor();
f.calibrateFromPoints(ValuesBefore, ValuesAfter);
f.get_module().saveToFlash();

You will find, in the Examples\Prog-Calibration directory of the Delphi, VB, and C# libraries, an application allowing you to test the effects of the 1 to 5 point calibration.

Limitations

Due to storage and processing limitations of real values within Yoctopuce sensors, raw values and corrected values must conform to a few numeric consraints:

Only 3 decimals are taken into account (i.e. resolution is 0.001)
The lowest allowed value is -2'100'000
The highest allowed value is +2'100'000

Arbitrary interpolation

It is also possible to compute the interpolation instead of letting the module do it, in order to calculate a spline interpolation, for instance. To do so, you only need to store a callback in the API. This callback must specify the number of calibration points it is expecting.

public static double CustomInterpolation3Points(double rawValue, int calibType,
int[] parameters, double[] beforeValues, double[] afterValues)
{ double result;
// the value to be corrected is rawValue
// calibration points are in beforeValues and afterValues
result = .... // interpolation of your choice
return result;
}
YAPI.RegisterCalibrationHandler(3, CustomInterpolation3Points);

Note that these interpolation callbacks are global, and not specific to each function. Thus, each time someone requests a value from a module which contains in its flash memory the correct number of calibration points, the corresponding callback is called to correct the value before returning it, enabling thus a perfectly transparent measure correction.

23. Firmware Update

There are multiples way to update the firmware of a Yoctopuce module..

23.1. The VirtualHub or the YoctoHub

It is possible to update the firmware directly from the web interface of the VirtualHub or the YoctoHub. The configuration panel of the module has an "upgrade" button to start a wizard that will guide you through the firmware update procedure.

In case the firmware update fails for any reason, and the module does no start anymore, simply unplug the module then plug it back while maintaining the Yocto-button down. The module will boot in "firmware update" mode and will appear in the VirtualHub interface below the module list.

23.2. The command line library

All the command line tools can update Yoctopuce modules thanks to the downloadAndUpdate command. The module selection mechanism works like for a traditional command. The [target] is the name of the module that you want to update. You can also use the "any" or "all" aliases, or even a name list, where the names are separated by commas, without spaces.

C:\>Executable [options] [target] command [parameters]

The following example updates all the Yoctopuce modules connected by USB.

C:\>YModule all downloadAndUpdate
ok: Yocto-PowerRelay RELAYHI1-266C8(rev=15430) is up to date.
ok: 0 / 0 hubs in 0.000000s.
ok: 0 / 0 shields in 0.000000s.
ok: 1 / 1 devices in 0.130000s 0.130000s per device.
ok: All devices are now up to date.
C:\>

23.3. The Android application Yocto-Firmware

You can update your module firmware from your Android phone or tablet with the Yocto-Firmware application. This application lists all the Yoctopuce modules connected by USB and checks if a more recent firmware is available on www.yoctopuce.com. If a more recent firmware is available, you can update the module. The application is responsible for downloading and installing the new firmware while preserving the module parameters.

Please note: while the firmware is being updated, the module restarts several times. Android interprets a USB device reboot as a disconnection and reconnection of the USB device and asks the authorization to use the USB port again. The user must click on OK for the update process to end successfully.

23.4. Updating the firmware with the programming library

If you need to integrate firmware updates in your application, the libraries offer you an API to update your modules. ⁶²

Saving and restoring parameters

The get_allSettings() method returns a binary buffer enabling you to save a module persistent parameters. This function is very useful to save the network configuration of a YoctoHub for example.

YWireless wireless = YWireless.FindWireless("reference");
YModule m = wireless.get_module();
byte[] default_config = m.get_allSettings();
saveFile("default.bin", default_config);
...

You can then apply these parameters to other modules with the set_allSettings() method.

byte[] default_config = loadFile("default.bin");
YModule m = YModule.FirstModule();
while (m != null) {
if (m.get_productName() == "YoctoHub-Wireless") {
m.set_allSettings(default_config);
}
m = m.next();
}

Finding the correct firmware

The first step to update a Yoctopuce module is to find which firmware you must use. The checkFirmware(path, onlynew) method of the YModule object does exactly this. The method checks that the firmware given as argument (path) is compatible with the module. If the onlynew parameter is set, this method checks that the firmware is more recent than the version currently used by the module. When the file is not compatible (or if the file is older than the installed version), this method returns an empty string. In the opposite, if the file is valid, the method returns a file access path.

The following piece of code checks that the c:\tmp\METEOMK1.17328.byn is compatible with the module stored in the m variable .

YModule m = YModule.FirstModule();
...
...
string path = "c:\\tmp\METEOMK1.17328.byn";
string newfirm = m.checkFirmware(path, false);
if (newfirm != "") {
Console.WriteLine("firmware " + newfirm + " is compatible");
}
...

The argument can be a directory (instead of a file). In this case, the method checks all the files of the directory recursively and returns the most recent compatible firmware. The following piece of code checks whether there is a more recent firmware in the c:\tmp\ directory.

YModule m = YModule.FirstModule();
...
...
string path = "c:\\tmp";
string newfirm = m.checkFirmware(path, true);
if (newfirm != "") {
Console.WriteLine("firmware " + newfirm + " is compatible and newer");
}
...

You can also give the "www.yoctopuce.com" string as argument to check whether there is a more recent published firmware on Yoctopuce's web site. In this case, the method returns the firmware URL. You can use this URL to download the firmware on your disk or use this URL when updating the firmware (see below). Obviously, this possibility works only if your machine is connected to Internet.

YModule m = YModule.FirstModule();
...
...
string url = m.checkFirmware("www.yoctopuce.com", true);
if (url != "") {
Console.WriteLine("new firmware is available at " + url );
}
...

Updating the firmware

A firmware update can take several minutes. That is why the update process is run as a background task and is driven by the user code thanks to the YFirmwareUdpate class.

To update a Yoctopuce module, you must obtain an instance of the YFirmwareUdpate class with the updateFirmware method of a YModule object. The only parameter of this method is the path of the firmware that you want to install. This method does not immediately start the update, but returns a YFirmwareUdpate object configured to update the module.

string newfirm = m.checkFirmware("www.yoctopuce.com", true);
.....
YFirmwareUpdate fw_update = m.updateFirmware(newfirm);

The startUpdate() method starts the update as a background task. This background task automatically takes care of

saving the module parameters
restarting the module in "update" mode
updating the firmware
starting the module with the new firmware version
restoring the parameters

The get_progress() and get_progressMessage() methods enable you to follow the progression of the update. get_progress() returns the progression as a percentage (100 = update complete). get_progressMessage() returns a character string describing the current operation (deleting, writing, rebooting, ...). If the get_progress method returns a negative value, the update process failed. In this case, the get_progressMessage() returns an error message.

The following piece of code starts the update and displays the progress on the standard output.

YFirmwareUpdate fw_update = m.updateFirmware(newfirm);
....
int status = fw_update.startUpdate();
while (status < 100 && status >= 0) {
int newstatus = fw_update.get_progress();
if (newstatus != status) {
Console.WriteLine(status + "% "
+ fw_update.get_progressMessage());
}
YAPI.Sleep(500, ref errmsg);
status = newstatus;
}

if (status < 0) {
Console.WriteLine("Firmware Update failed: "
+ fw_update.get_progressMessage());
} else {
Console.WriteLine("Firmware Updated Successfully!");
}

An Android characteristic

You can update a module firmware using the Android library. However, for modules connected by USB, Android asks the user to authorize the application to access the USB port.

During firmware update, the module restarts several times. Android interprets a USB device reboot as a disconnection and a reconnection to the USB port, and prevents all USB access as long as the user has not closed the pop-up window. The use has to click on OK for the update process to continue correctly. You cannot update a module connected by USB to an Android device without having the user interacting with the device.

23.5. The "update" mode

If you want to erase all the parameters of a module or if your module does not start correctly anymore, you can install a firmware from the "update" mode.

To force the module to work in "update" mode, disconnect it, wait a few seconds, and reconnect it while maintaining the Yocto-button down. This will restart the module in "update" mode. This update mode is protected against corruptions and is always available.

In this mode, the module is not detected by the YModule objects anymore. To obtain the list of connected modules in "update" mode, you must use the YAPI.GetAllBootLoaders() function. This function returns a character string array with the serial numbers of the modules in "update" mode.

List<string> allBootLoader = YAPI.GetAllBootLoaders();

The update process is identical to the standard case (see the preceding section), but you must manually instantiate the YFirmwareUpdate object instead of calling module.updateFirmware(). The constructor takes as argument three parameters: the module serial number, the path of the firmware to be installed, and a byte array with the parameters to be restored at the end of the update (or null to restore default parameters).

YFirmwareUpdateupdate fw_update;
fw_update = new YFirmwareUpdate(allBootLoader[0], newfirm, null);
int status = fw_update.startUpdate();
.....

24. High-level API Reference

This chapter summarizes the high-level API functions to drive your Yocto-RS485. Syntax and exact type names may vary from one language to another, but, unless otherwise stated, all the functions are available in every language. For detailed information regarding the types of arguments and return values for a given language, refer to the definition file for this language (yocto_api.* as well as the other yocto_* files that define the function interfaces).

For languages which support exceptions, all of these functions throw exceptions in case of error by default, rather than returning the documented error value for each function. This is by design, to facilitate debugging. It is however possible to disable the use of exceptions using the yDisableExceptions() function, in case you prefer to work with functions that return error values.

This chapter does not repeat the programming concepts described earlier, in order to stay as concise as possible. In case of doubt, do not hesitate to go back to the chapter describing in details all configurable attributes.

24.1. Class YAPI

General functions

These general functions should be used to initialize and configure the Yoctopuce library. In most cases, a simple call to function yRegisterHub() should be enough. The module-specific functions yFind...() or yFirst...() should then be used to retrieve an object that provides interaction with the module.

In order to use the functions described here, you should include:

java	import com.yoctopuce.YoctoAPI.YAPI;
dnp	import YoctoProxyAPI.YAPIProxy
cp	#include "yocto_api_proxy.h"
ml	import YoctoProxyAPI.YAPIProxy"
js	<script type='text/javascript' src='yocto_api.js'></script>
cpp	#include "yocto_api.h"
m	#import "yocto_api.h"
pas	uses yocto_api;
vb	yocto_api.vb
cs	yocto_api.cs
uwp	import com.yoctopuce.YoctoAPI.YModule;
py	from yocto_api import *
php	require_once('yocto_api.php');
es	in HTML: <script src="../../lib/yocto_api.js"></script> in node.js: require('yoctolib-es2017/yocto_api.js');
vi	YModule.vi

Global functions
YAPI.CheckLogicalName(name)
Checks if a given string is valid as logical name for a module or a function.
YAPI.ClearHTTPCallbackCacheDir(bool_removeFiles)
Disables the HTTP callback cache.
YAPI.DisableExceptions()
Disables the use of exceptions to report runtime errors.
YAPI.EnableExceptions()
Re-enables the use of exceptions for runtime error handling.
YAPI.EnableUSBHost(osContext)
This function is used only on Android.
YAPI.FreeAPI()
Waits for all pending communications with Yoctopuce devices to be completed then frees dynamically allocated resources used by the Yoctopuce library.
YAPI.GetAPIVersion()
Returns the version identifier for the Yoctopuce library in use.
YAPI.GetCacheValidity()
Returns the validity period of the data loaded by the library.
YAPI.GetDeviceListValidity()
Returns the delay between each forced enumeration of the used YoctoHubs.
YAPI.GetDllArchitecture()
Returns the system architecture for the Yoctopuce communication library in use.
YAPI.GetDllPath()
Returns the paths of the DLLs for the Yoctopuce library in use.
YAPI.GetLog(lastLogLine)
Retrieves Yoctopuce low-level library diagnostic logs.
YAPI.GetNetworkTimeout()
Returns the network connection delay for `yRegisterHub()` and `yUpdateDeviceList()`.
YAPI.GetTickCount()
Returns the current value of a monotone millisecond-based time counter.
YAPI.HandleEvents(errmsg)
Maintains the device-to-library communication channel.
YAPI.InitAPI(mode, errmsg)
Initializes the Yoctopuce programming library explicitly.
YAPI.PreregisterHub(url, errmsg)
Fault-tolerant alternative to `yRegisterHub()`.
YAPI.RegisterDeviceArrivalCallback(arrivalCallback)
Register a callback function, to be called each time a device is plugged.
YAPI.RegisterDeviceRemovalCallback(removalCallback)
Register a callback function, to be called each time a device is unplugged.
YAPI.RegisterHub(url, errmsg)
Setup the Yoctopuce library to use modules connected on a given machine.
YAPI.RegisterHubDiscoveryCallback(hubDiscoveryCallback)
Register a callback function, to be called each time an Network Hub send an SSDP message.
YAPI.RegisterHubWebsocketCallback(ws, errmsg, authpwd)
Variant to `yRegisterHub()` used to initialize Yoctopuce API on an existing Websocket session, as happens for incoming WebSocket callbacks.
YAPI.RegisterLogFunction(logfun)
Registers a log callback function.
YAPI.SelectArchitecture(arch)
Select the architecture or the library to be loaded to access to USB.
YAPI.SetCacheValidity(cacheValidityMs)
Change the validity period of the data loaded by the library.
YAPI.SetDelegate(object)
(Objective-C only) Register an object that must follow the protocol `YDeviceHotPlug`.
YAPI.SetDeviceListValidity(deviceListValidity)
Modifies the delay between each forced enumeration of the used YoctoHubs.
YAPI.SetHTTPCallbackCacheDir(str_directory)
Enables the HTTP callback cache.
YAPI.SetNetworkTimeout(networkMsTimeout)
Modifies the network connection delay for `yRegisterHub()` and `yUpdateDeviceList()`.
YAPI.SetTimeout(callback, ms_timeout, args)
Invoke the specified callback function after a given timeout.
YAPI.SetUSBPacketAckMs(pktAckDelay)
Enables the acknowledge of every USB packet received by the Yoctopuce library.
YAPI.Sleep(ms_duration, errmsg)
Pauses the execution flow for a specified duration.
YAPI.TestHub(url, mstimeout, errmsg)
Test if the hub is reachable.
YAPI.TriggerHubDiscovery(errmsg)
Force a hub discovery, if a callback as been registered with `yRegisterHubDiscoveryCallback` it will be called for each net work hub that will respond to the discovery.
YAPI.UnregisterHub(url)
Setup the Yoctopuce library to no more use modules connected on a previously registered machine with RegisterHub.
YAPI.UpdateDeviceList(errmsg)
Triggers a (re)detection of connected Yoctopuce modules.
YAPI.UpdateDeviceList_async(callback, context)
Triggers a (re)detection of connected Yoctopuce modules.

YAPI.CheckLogicalName()
YAPI.CheckLogicalName()yCheckLogicalName()yCheckLogicalName()[YAPI CheckLogicalName: ]yCheckLogicalName()yCheckLogicalName()YAPI.CheckLogicalName()YAPI.CheckLogicalName()YAPI.CheckLogicalName()YAPI.CheckLogicalName()yCheckLogicalName()YAPI.CheckLogicalName()

Checks if a given string is valid as logical name for a module or a function.

function yCheckLogicalName(

name)

cpp

bool yCheckLogicalName(

string name)

+(BOOL) CheckLogicalName

:(NSString *) name

pas

boolean yCheckLogicalName(

name: string): boolean

function yCheckLogicalName(

ByVal name As String) As Boolean

static bool CheckLogicalName(

string name)

java

boolean CheckLogicalName(

String name)

uwp

bool CheckLogicalName(

string name)

CheckLogicalName(

name)

php

function yCheckLogicalName(

$name)

async CheckLogicalName(

name)

A valid logical name has a maximum of 19 characters, all among A..Z, a..z, 0..9, _, and -. If you try to configure a logical name with an incorrect string, the invalid characters are ignored.

Parameters :

name	a string containing the name to check.

Returns :

true if the name is valid, false otherwise.

YAPI.ClearHTTPCallbackCacheDir()
YAPI.ClearHTTPCallbackCacheDir()yClearHTTPCallbackCacheDir()

Disables the HTTP callback cache.

php

function yClearHTTPCallbackCacheDir(

$bool_removeFiles)

This method disables the HTTP callback cache, and can additionally cleanup the cache directory.

Parameters :

bool_removeFiles True to clear the content of the cache.

Returns :

nothing.

YAPI.DisableExceptions()
YAPI.DisableExceptions()yDisableExceptions()yDisableExceptions()[YAPI DisableExceptions]yDisableExceptions()yDisableExceptions()YAPI.DisableExceptions()YAPI.DisableExceptions()YAPI.DisableExceptions()yDisableExceptions()YAPI.DisableExceptions()

Disables the use of exceptions to report runtime errors.

function yDisableExceptions(

)

cpp

void yDisableExceptions(

)

+(void) DisableExceptions

pas

yDisableExceptions(

)

procedure yDisableExceptions(

)

static void DisableExceptions(

)

uwp

void DisableExceptions(

)

DisableExceptions(

)

php

function yDisableExceptions(

)

async DisableExceptions(

)

When exceptions are disabled, every function returns a specific error value which depends on its type and which is documented in this reference manual.

YAPI.EnableExceptions()
YAPI.EnableExceptions()yEnableExceptions()yEnableExceptions()[YAPI EnableExceptions]yEnableExceptions()yEnableExceptions()YAPI.EnableExceptions()YAPI.EnableExceptions()YAPI.EnableExceptions()yEnableExceptions()YAPI.EnableExceptions()

Re-enables the use of exceptions for runtime error handling.

function yEnableExceptions(

)

cpp

void yEnableExceptions(

)

+(void) EnableExceptions

pas

yEnableExceptions(

)

procedure yEnableExceptions(

)

static void EnableExceptions(

)

uwp

void EnableExceptions(

)

EnableExceptions(

)

php

function yEnableExceptions(

)

async EnableExceptions(

)

Be aware than when exceptions are enabled, every function that fails triggers an exception. If the exception is not caught by the user code, it either fires the debugger or aborts (i.e. crash) the program. On failure, throws an exception or returns a negative error code.

YAPI.EnableUSBHost()
YAPI.EnableUSBHost()YAPI.EnableUSBHost()

This function is used only on Android.

java

void EnableUSBHost(

Object osContext)

Before calling yRegisterHub("usb") you need to activate the USB host port of the system. This function takes as argument, an object of class android.content.Context (or any subclass). It is not necessary to call this function to reach modules through the network.

Parameters :

On failure, throws an exception.

osContext an object of class android.content.Context (or any subclass).

YAPI.FreeAPI()
YAPI.FreeAPI()yFreeAPI()yFreeAPI()[YAPI FreeAPI]yFreeAPI()yFreeAPI()YAPI.FreeAPI()YAPI.FreeAPI()YAPI.FreeAPI()YAPI.FreeAPI()yFreeAPI()YAPI.FreeAPI()YAPI.FreeAPI()YAPI.FreeAPI()

Waits for all pending communications with Yoctopuce devices to be completed then frees dynamically allocated resources used by the Yoctopuce library.

function yFreeAPI(

)

cpp

void yFreeAPI(

)

+(void) FreeAPI

pas

yFreeAPI(

)

procedure yFreeAPI(

)

static void FreeAPI(

)

java

void FreeAPI(

)

uwp

void FreeAPI(

)

FreeAPI(

)

php

function yFreeAPI(

)

async FreeAPI(

)

dnp

static void FreeAPI(

)

static void FreeAPI(

)

From an operating system standpoint, it is generally not required to call this function since the OS will automatically free allocated resources once your program is completed. However there are two situations when you may really want to use that function: - Free all dynamically allocated memory blocks in order to track a memory leak. - Send commands to devices right before the end of the program. Since commands are sent in an asynchronous way the program could exit before all commands are effectively sent. You should not call any other library function after calling yFreeAPI(), or your program will crash.

YAPI.GetAPIVersion()
YAPI.GetAPIVersion()yGetAPIVersion()yGetAPIVersion()[YAPI GetAPIVersion]yGetAPIVersion()yGetAPIVersion()YAPI.GetAPIVersion()YAPI.GetAPIVersion()YAPI.GetAPIVersion()YAPI.GetAPIVersion()yGetAPIVersion()YAPI.GetAPIVersion()YAPI.GetAPIVersion()YAPI.GetAPIVersion()

Returns the version identifier for the Yoctopuce library in use.

function yGetAPIVersion(

)

cpp

string yGetAPIVersion(

)

+(NSString*) GetAPIVersion

pas

string yGetAPIVersion(

): string

function yGetAPIVersion(

) As String

static String GetAPIVersion(

)

java

static String GetAPIVersion(

)

uwp

static string GetAPIVersion(

)

GetAPIVersion(

)

php

function yGetAPIVersion(

)

async GetAPIVersion(

)

dnp

static string GetAPIVersion(

)

static string GetAPIVersion(

)

The version is a string in the form "Major.Minor.Build", for instance "1.01.5535". For languages using an external DLL (for instance C#, VisualBasic or Delphi), the character string includes as well the DLL version, for instance "1.01.5535 (1.01.5439)".

If you want to verify in your code that the library version is compatible with the version that you have used during development, verify that the major number is strictly equal and that the minor number is greater or equal. The build number is not relevant with respect to the library compatibility.

Returns :

a character string describing the library version.

YAPI.GetCacheValidity()
YAPI.GetCacheValidity()yGetCacheValidity()[YAPI GetCacheValidity]yGetCacheValidity()yGetCacheValidity()YAPI.GetCacheValidity()YAPI.GetCacheValidity()YAPI.GetCacheValidity()YAPI.GetCacheValidity()yGetCacheValidity()YAPI.GetCacheValidity()

Returns the validity period of the data loaded by the library.

cpp

static u64 yGetCacheValidity(

)

+(u64) GetCacheValidity

pas

u64 yGetCacheValidity(

): u64

function yGetCacheValidity(

) As Long

ulong GetCacheValidity(

)

java

long GetCacheValidity(

)

uwp

async Task<ulong> GetCacheValidity(

)

GetCacheValidity(

)

php

function yGetCacheValidity(

)

async GetCacheValidity(

)

This method returns the cache validity of all attributes module functions. Note: This function must be called after yInitAPI .

Returns :

an integer corresponding to the validity attributed to the loaded function parameters, in milliseconds

YAPI.GetDeviceListValidity()
YAPI.GetDeviceListValidity()yGetDeviceListValidity()[YAPI GetDeviceListValidity]yGetDeviceListValidity()yGetDeviceListValidity()YAPI.GetDeviceListValidity()YAPI.GetDeviceListValidity()YAPI.GetDeviceListValidity()YAPI.GetDeviceListValidity()yGetDeviceListValidity()YAPI.GetDeviceListValidity()

Returns the delay between each forced enumeration of the used YoctoHubs.

cpp

static int yGetDeviceListValidity(

)

+(int) GetDeviceListValidity

pas

LongInt yGetDeviceListValidity(

): LongInt

function yGetDeviceListValidity(

) As Integer

int GetDeviceListValidity(

)

java

int GetDeviceListValidity(

)

uwp

async Task<int> GetDeviceListValidity(

)

GetDeviceListValidity(

)

php

function yGetDeviceListValidity(

)

async GetDeviceListValidity(

)

Note: you must call this function after yInitAPI.

Returns :

the number of seconds between each enumeration.

YAPI.GetDllArchitecture()
YAPI.GetDllArchitecture()YAPI.GetDllArchitecture()

Returns the system architecture for the Yoctopuce communication library in use.

dnp

static string GetDllArchitecture(

)

On Windows, the architecture can be "Win32" or "Win64". On ARM machines, the architecture is "Armhf32" or "Aarch64". On other Linux machines, the architecture is "Linux32" or "Linux64". On MacOS, the architecture is "MacOs32" or "MacOs64".

Returns :

a character string describing the system architecture of the low-level communication library.

YAPI.GetDllPath()
YAPI.GetDllPath()YAPI.GetDllPath()

Returns the paths of the DLLs for the Yoctopuce library in use.

dnp

static string GetDllPath(

)

For architectures that require multiple DLLs, in particular when using a .NET assembly DLL, the returned string takes the form "DotNetProxy=/...; yapi=/...;", where the first path corresponds to the .NET assembly DLL and the second path corresponds to the low-level communication library.

Returns :

a character string describing the DLL path.

YAPI.GetLog()
YAPI.GetLog()YAPI.GetLog()YAPI.GetLog()

Retrieves Yoctopuce low-level library diagnostic logs.

dnp

static string GetLog(

string lastLogLine)

static string GetLog(

string)

This method allows to progessively retrieve API logs. The interface is line-based: it must called it within a loop until the returned value is an empty string. Make sure to exit the loop when an empty string is returned, as feeding an empty string into the lastLogLine parameter for the next call would restart enumerating logs from the oldest message available.

Parameters :

lastLogLine On first call, provide an empty string. On subsequent calls, provide the last log line returned by GetLog().

Returns :

a string with the log line immediately following the one given in argument, if such line exist. Returns an empty string otherwise, when completed.

YAPI.GetNetworkTimeout()
YAPI.GetNetworkTimeout()yGetNetworkTimeout()[YAPI GetNetworkTimeout]yGetNetworkTimeout()yGetNetworkTimeout()YAPI.GetNetworkTimeout()YAPI.GetNetworkTimeout()YAPI.GetNetworkTimeout()YAPI.GetNetworkTimeout()yGetNetworkTimeout()YAPI.GetNetworkTimeout()YAPI.GetNetworkTimeout()YAPI.GetNetworkTimeout()

Returns the network connection delay for yRegisterHub() and yUpdateDeviceList().

cpp

static int yGetNetworkTimeout(

)

+(int) GetNetworkTimeout

pas

LongInt yGetNetworkTimeout(

): LongInt

function yGetNetworkTimeout(

) As Integer

int GetNetworkTimeout(

)

java

int GetNetworkTimeout(

)

uwp

async Task<int> GetNetworkTimeout(

)

GetNetworkTimeout(

)

php

function yGetNetworkTimeout(

)

async GetNetworkTimeout(

)

dnp

static int GetNetworkTimeout(

)

static int GetNetworkTimeout(

)

This delay impacts only the YoctoHubs and VirtualHub which are accessible through the network. By default, this delay is of 20000 milliseconds, but depending or you network you may want to change this delay, for example if your network infrastructure is based on a GSM connection.

Returns :

the network connection delay in milliseconds.

YAPI.GetTickCount()
YAPI.GetTickCount()yGetTickCount()yGetTickCount()[YAPI GetTickCount]yGetTickCount()yGetTickCount()YAPI.GetTickCount()YAPI.GetTickCount()YAPI.GetTickCount()YAPI.GetTickCount()yGetTickCount()YAPI.GetTickCount()

Returns the current value of a monotone millisecond-based time counter.

function yGetTickCount(

)

cpp

u64 yGetTickCount(

)

+(u64) GetTickCount

pas

u64 yGetTickCount(

): u64

function yGetTickCount(

) As Long

static ulong GetTickCount(

)

java

static long GetTickCount(

)

uwp

static ulong GetTickCount(

)

GetTickCount(

)

php

function yGetTickCount(

)

GetTickCount(

)

This counter can be used to compute delays in relation with Yoctopuce devices, which also uses the millisecond as timebase.

Returns :

a long integer corresponding to the millisecond counter.

YAPI.HandleEvents()
YAPI.HandleEvents()yHandleEvents()yHandleEvents()[YAPI HandleEvents: ]yHandleEvents()yHandleEvents()YAPI.HandleEvents()YAPI.HandleEvents()YAPI.HandleEvents()YAPI.HandleEvents()yHandleEvents()YAPI.HandleEvents()

Maintains the device-to-library communication channel.

function yHandleEvents(

errmsg)

cpp

YRETCODE yHandleEvents(

string errmsg)

+(YRETCODE) HandleEvents

:(NSError**) errmsg

pas

integer yHandleEvents(

var errmsg: string): integer

function yHandleEvents(

ByRef errmsg As String) As YRETCODE

static YRETCODE HandleEvents(

ref string errmsg)

java

int HandleEvents(

)

uwp

async Task<int> HandleEvents(

)

HandleEvents(

errmsg=None)

php

function yHandleEvents(

&$errmsg)

async HandleEvents(

errmsg)

If your program includes significant loops, you may want to include a call to this function to make sure that the library takes care of the information pushed by the modules on the communication channels. This is not strictly necessary, but it may improve the reactivity of the library for the following commands.

This function may signal an error in case there is a communication problem while contacting a module.

Parameters :

errmsg a string passed by reference to receive any error message.

Returns :

YAPI_SUCCESS when the call succeeds.

On failure, throws an exception or returns a negative error code.

YAPI.InitAPI()
YAPI.InitAPI()yInitAPI()yInitAPI()[YAPI InitAPI: ]yInitAPI()yInitAPI()YAPI.InitAPI()YAPI.InitAPI()YAPI.InitAPI()YAPI.InitAPI()yInitAPI()YAPI.InitAPI()

Initializes the Yoctopuce programming library explicitly.

function yInitAPI(

mode, errmsg)

cpp

YRETCODE yInitAPI(

int mode, string errmsg)

+(YRETCODE) InitAPI

:(int) mode :(NSError**) errmsg

pas

integer yInitAPI(

mode: integer, var errmsg: string): integer

function yInitAPI(

ByVal mode As Integer, ByRef errmsg As String) As Integer

static int InitAPI(

int mode, ref string errmsg)

java

int InitAPI(

int mode)

uwp

async Task<int> InitAPI(

int mode)

InitAPI(

mode, errmsg=None)

php

function yInitAPI(

$mode, &$errmsg)

async InitAPI(

mode, errmsg)

It is not strictly needed to call yInitAPI(), as the library is automatically initialized when calling yRegisterHub() for the first time.

When Y_DETECT_NONE is used as detection mode, you must explicitly use yRegisterHub() to point the API to the VirtualHub on which your devices are connected before trying to access them.

Parameters :

mode	an integer corresponding to the type of automatic device detection to use. Possible values are `Y_DETECT_NONE`, `Y_DETECT_USB`, `Y_DETECT_NET`, and `Y_DETECT_ALL`.
errmsg	a string passed by reference to receive any error message.

Returns :

YAPI_SUCCESS when the call succeeds.

On failure, throws an exception or returns a negative error code.

YAPI.PreregisterHub()
YAPI.PreregisterHub()yPreregisterHub()yPreregisterHub()[YAPI PreregisterHub: ]yPreregisterHub()yPreregisterHub()YAPI.PreregisterHub()YAPI.PreregisterHub()YAPI.PreregisterHub()YAPI.PreregisterHub()yPreregisterHub()YAPI.PreregisterHub()YAPI.PreregisterHub()YAPI.PreregisterHub()

Fault-tolerant alternative to yRegisterHub().

function yPreregisterHub(

url, errmsg)

cpp

YRETCODE yPreregisterHub(

string url, string errmsg)

+(YRETCODE) PreregisterHub

:(NSString *) url :(NSError**) errmsg

pas

integer yPreregisterHub(

url: string, var errmsg: string): integer

vb	function yPreregisterHub(	ByVal url As String,
		ByRef errmsg As String) As Integer

static int PreregisterHub(

string url, ref string errmsg)

java

int PreregisterHub(

String url)

uwp

async Task<int> PreregisterHub(

string url)

PreregisterHub(

url, errmsg=None)

php

function yPreregisterHub(

$url, &$errmsg)

async PreregisterHub(

url, errmsg)

dnp

static string PreregisterHub(

string url)

static string PreregisterHub(

string)

This function has the same purpose and same arguments as yRegisterHub(), but does not trigger an error when the selected hub is not available at the time of the function call. This makes it possible to register a network hub independently of the current connectivity, and to try to contact it only when a device is actively needed.

Parameters :

url	a string containing either "usb","callback" or the root URL of the hub to monitor
errmsg	a string passed by reference to receive any error message.

Returns :

YAPI_SUCCESS when the call succeeds.

On failure, throws an exception or returns a negative error code.

YAPI.RegisterDeviceArrivalCallback()
YAPI.RegisterDeviceArrivalCallback()yRegisterDeviceArrivalCallback()yRegisterDeviceArrivalCallback()[YAPI RegisterDeviceArrivalCallback: ]yRegisterDeviceArrivalCallback()yRegisterDeviceArrivalCallback()YAPI.RegisterDeviceArrivalCallback()YAPI.RegisterDeviceArrivalCallback()YAPI.RegisterDeviceArrivalCallback()YAPI.RegisterDeviceArrivalCallback()yRegisterDeviceArrivalCallback()YAPI.RegisterDeviceArrivalCallback()

function yRegisterDeviceArrivalCallback(

arrivalCallback)

cpp

void yRegisterDeviceArrivalCallback(

yDeviceUpdateCallback arrivalCallback)

+(void) RegisterDeviceArrivalCallback

:(yDeviceUpdateCallback) arrivalCallback

pas

yRegisterDeviceArrivalCallback(

arrivalCallback: yDeviceUpdateFunc)

procedure yRegisterDeviceArrivalCallback(

ByVal arrivalCallback As yDeviceUpdateFunc)

static void RegisterDeviceArrivalCallback(

yDeviceUpdateFunc arrivalCallback)

java

void RegisterDeviceArrivalCallback(

DeviceArrivalCallback arrivalCallback)

uwp

void RegisterDeviceArrivalCallback(

DeviceUpdateHandler arrivalCallback)

RegisterDeviceArrivalCallback(

arrivalCallback)

php

function yRegisterDeviceArrivalCallback(

$arrivalCallback)

async RegisterDeviceArrivalCallback(

arrivalCallback)

This callback will be invoked while yUpdateDeviceList is running. You will have to call this function on a regular basis.

Parameters :

to unregister a previously registered callback.

arrivalCallback a procedure taking a YModule parameter, or null

YAPI.RegisterDeviceRemovalCallback()
YAPI.RegisterDeviceRemovalCallback()yRegisterDeviceRemovalCallback()yRegisterDeviceRemovalCallback()[YAPI RegisterDeviceRemovalCallback: ]yRegisterDeviceRemovalCallback()yRegisterDeviceRemovalCallback()YAPI.RegisterDeviceRemovalCallback()YAPI.RegisterDeviceRemovalCallback()YAPI.RegisterDeviceRemovalCallback()YAPI.RegisterDeviceRemovalCallback()yRegisterDeviceRemovalCallback()YAPI.RegisterDeviceRemovalCallback()

function yRegisterDeviceRemovalCallback(

removalCallback)

cpp

void yRegisterDeviceRemovalCallback(

yDeviceUpdateCallback removalCallback)

+(void) RegisterDeviceRemovalCallback

:(yDeviceUpdateCallback) removalCallback

pas

yRegisterDeviceRemovalCallback(

removalCallback: yDeviceUpdateFunc)

procedure yRegisterDeviceRemovalCallback(

ByVal removalCallback As yDeviceUpdateFunc)

static void RegisterDeviceRemovalCallback(

yDeviceUpdateFunc removalCallback)

java

void RegisterDeviceRemovalCallback(

DeviceRemovalCallback removalCallback)

uwp

void RegisterDeviceRemovalCallback(

DeviceUpdateHandler removalCallback)

RegisterDeviceRemovalCallback(

removalCallback)

php

function yRegisterDeviceRemovalCallback(

$removalCallback)

async RegisterDeviceRemovalCallback(

removalCallback)

This callback will be invoked while yUpdateDeviceList is running. You will have to call this function on a regular basis.

Parameters :

to unregister a previously registered callback.

removalCallback a procedure taking a YModule parameter, or null

YAPI.RegisterHub()
YAPI.RegisterHub()yRegisterHub()yRegisterHub()[YAPI RegisterHub: ]yRegisterHub()yRegisterHub()YAPI.RegisterHub()YAPI.RegisterHub()YAPI.RegisterHub()YAPI.RegisterHub()yRegisterHub()YAPI.RegisterHub()YAPI.RegisterHub()YAPI.RegisterHub()

Setup the Yoctopuce library to use modules connected on a given machine.

function yRegisterHub(

url, errmsg)

cpp

YRETCODE yRegisterHub(

string url, string errmsg)

+(YRETCODE) RegisterHub

:(NSString *) url :(NSError**) errmsg

pas

integer yRegisterHub(

url: string, var errmsg: string): integer

vb	function yRegisterHub(	ByVal url As String,
		ByRef errmsg As String) As Integer

static int RegisterHub(

string url, ref string errmsg)

java

int RegisterHub(

String url)

uwp

async Task<int> RegisterHub(

string url)

RegisterHub(

url, errmsg=None)

php

function yRegisterHub(

$url, &$errmsg)

async RegisterHub(

url, errmsg)

dnp

static string RegisterHub(

string url)

static string RegisterHub(

string)

The parameter will determine how the API will work. Use the following values:

usb: When the usb keyword is used, the API will work with devices connected directly to the USB bus. Some programming languages such a JavaScript, PHP, and Java don't provide direct access to USB hardware, so usb will not work with these. In this case, use a VirtualHub or a networked YoctoHub (see below).

x.x.x.x or hostname: The API will use the devices connected to the host with the given IP address or hostname. That host can be a regular computer running a VirtualHub, or a networked YoctoHub such as YoctoHub-Ethernet or YoctoHub-Wireless. If you want to use the VirtualHub running on you local computer, use the IP address 127.0.0.1.

callback: that keyword make the API run in "HTTP Callback" mode. This a special mode allowing to take control of Yoctopuce devices through a NAT filter when using a VirtualHub or a networked YoctoHub. You only need to configure your hub to call your server script on a regular basis. This mode is currently available for PHP and Node.JS only.

Be aware that only one application can use direct USB access at a given time on a machine. Multiple access would cause conflicts while trying to access the USB modules. In particular, this means that you must stop the VirtualHub software before starting an application that uses direct USB access. The workaround for this limitation is to setup the library to use the VirtualHub rather than direct USB access.

If access control has been activated on the hub, virtual or not, you want to reach, the URL parameter should look like:

http://username:password@address:port

You can call RegisterHub several times to connect to several machines.

Parameters :

url	a string containing either "usb","callback" or the root URL of the hub to monitor
errmsg	a string passed by reference to receive any error message.

Returns :

YAPI_SUCCESS when the call succeeds.

On failure, throws an exception or returns a negative error code.

YAPI.RegisterHubDiscoveryCallback()
YAPI.RegisterHubDiscoveryCallback()yRegisterHubDiscoveryCallback()[YAPI RegisterHubDiscoveryCallback: ]yRegisterHubDiscoveryCallback()yRegisterHubDiscoveryCallback()YAPI.RegisterHubDiscoveryCallback()YAPI.RegisterHubDiscoveryCallback()YAPI.RegisterHubDiscoveryCallback()YAPI.RegisterHubDiscoveryCallback()YAPI.RegisterHubDiscoveryCallback()

cpp

void yRegisterHubDiscoveryCallback(

YHubDiscoveryCallback hubDiscoveryCallback)

+(void) RegisterHubDiscoveryCallback

: (YHubDiscoveryCallback) hubDiscoveryCallback

pas

yRegisterHubDiscoveryCallback(

hubDiscoveryCallback: YHubDiscoveryCallback)

procedure yRegisterHubDiscoveryCallback(

ByVal hubDiscoveryCallback As YHubDiscoveryCallback)

static void RegisterHubDiscoveryCallback(

YHubDiscoveryCallback hubDiscoveryCallback)

java

void RegisterHubDiscoveryCallback(

HubDiscoveryCallback hubDiscoveryCallback)

uwp

async Task RegisterHubDiscoveryCallback(

HubDiscoveryHandler hubDiscoveryCallback)

RegisterHubDiscoveryCallback(

hubDiscoveryCallback)

async RegisterHubDiscoveryCallback(

hubDiscoveryCallback)

The callback has two string parameter, the first one contain the serial number of the hub and the second contain the URL of the network hub (this URL can be passed to RegisterHub). This callback will be invoked while yUpdateDeviceList is running. You will have to call this function on a regular basis.

Parameters :

number and the hub URL. Use null to unregister a previously registered callback.

hubDiscoveryCallback a procedure taking two string parameter, the serial

YAPI.RegisterHubWebsocketCallback()
YAPI.RegisterHubWebsocketCallback()

Variant to yRegisterHub() used to initialize Yoctopuce API on an existing Websocket session, as happens for incoming WebSocket callbacks.

Parameters :

ws	node WebSocket object for the incoming WebSocket callback connection
errmsg	a string passed by reference to receive any error message.
authpwd	the optional authentication password, required only authentication is configured on the calling hub.

Returns :

YAPI_SUCCESS when the call succeeds.

On failure, throws an exception or returns a negative error code.

YAPI.RegisterLogFunction()
YAPI.RegisterLogFunction()yRegisterLogFunction()[YAPI RegisterLogFunction: ]yRegisterLogFunction()yRegisterLogFunction()YAPI.RegisterLogFunction()YAPI.RegisterLogFunction()YAPI.RegisterLogFunction()YAPI.RegisterLogFunction()YAPI.RegisterLogFunction()

Registers a log callback function.

cpp

void yRegisterLogFunction(

yLogFunction logfun)

+(void) RegisterLogFunction

:(yLogCallback) logfun

pas

yRegisterLogFunction(

logfun: yLogFunc)

procedure yRegisterLogFunction(

ByVal logfun As yLogFunc)

static void RegisterLogFunction(

yLogFunc logfun)

java

void RegisterLogFunction(

LogCallback logfun)

uwp

void RegisterLogFunction(

LogHandler logfun)

RegisterLogFunction(

logfun)

async RegisterLogFunction(

logfun)

This callback will be called each time the API have something to say. Quite useful to debug the API.

Parameters :

to unregister a previously registered callback.

logfun a procedure taking a string parameter, or null

YAPI.SelectArchitecture()
YAPI.SelectArchitecture()YAPI.SelectArchitecture()

Select the architecture or the library to be loaded to access to USB.

SelectArchitecture(

arch)

By default, the Python library automatically detects the appropriate library to use. However, for Linux ARM, it not possible to reliably distinguish between a Hard Float (armhf) and a Soft Float (armel) install. For in this case, it is therefore recommended to manually select the proper architecture by calling SelectArchitecture() before any other call to the library.

Parameters :

arch	A string containing the architecture to use. Possibles value are: `"armhf"`,`"armel"`, `"aarch64"`,`"i386"`,`"x86_64"`, `"32bit"`, `"64bit"`

Returns :

nothing.

On failure, throws an exception.

YAPI.SetCacheValidity()
YAPI.SetCacheValidity()ySetCacheValidity()[YAPI SetCacheValidity: ]ySetCacheValidity()ySetCacheValidity()YAPI.SetCacheValidity()YAPI.SetCacheValidity()YAPI.SetCacheValidity()YAPI.SetCacheValidity()ySetCacheValidity()YAPI.SetCacheValidity()

Change the validity period of the data loaded by the library.

cpp

static void ySetCacheValidity(

u64 cacheValidityMs)

+(void) SetCacheValidity

: (u64) cacheValidityMs

pas

ySetCacheValidity(

cacheValidityMs: u64)

procedure ySetCacheValidity(

ByVal cacheValidityMs As Long)

void SetCacheValidity(

ulong cacheValidityMs)

java

void SetCacheValidity(

long cacheValidityMs)

uwp

async Task SetCacheValidity(

ulong cacheValidityMs)

SetCacheValidity(

cacheValidityMs)

php

function ySetCacheValidity(

$cacheValidityMs)

async SetCacheValidity(

cacheValidityMs)

By default, when accessing a module, all the attributes of the module functions are automatically kept in cache for the standard duration (5 ms). This method can be used to change this standard duration, for example in order to reduce network or USB traffic. This parameter does not affect value change callbacks Note: This function must be called after yInitAPI.

Parameters :

cacheValidityMs an integer corresponding to the validity attributed to the loaded function parameters, in milliseconds.

YAPI.SetDelegate()
YAPI.SetDelegate()[YAPI SetDelegate: ]

(Objective-C only) Register an object that must follow the protocol YDeviceHotPlug.

+(void) SetDelegate

:(id) object

The methods yDeviceArrival and yDeviceRemoval will be invoked while yUpdateDeviceList is running. You will have to call this function on a regular basis.

Parameters :

to unregister a previously registered object.

object an object that must follow the protocol YAPIDelegate, or nil

YAPI.SetDeviceListValidity()
YAPI.SetDeviceListValidity()ySetDeviceListValidity()[YAPI SetDeviceListValidity: ]ySetDeviceListValidity()ySetDeviceListValidity()YAPI.SetDeviceListValidity()YAPI.SetDeviceListValidity()YAPI.SetDeviceListValidity()YAPI.SetDeviceListValidity()ySetDeviceListValidity()YAPI.SetDeviceListValidity()

Modifies the delay between each forced enumeration of the used YoctoHubs.

cpp

static void ySetDeviceListValidity(

int deviceListValidity)

+(void) SetDeviceListValidity

: (int) deviceListValidity

pas

ySetDeviceListValidity(

deviceListValidity: LongInt)

procedure ySetDeviceListValidity(

ByVal deviceListValidity As Integer)

void SetDeviceListValidity(

int deviceListValidity)

java

void SetDeviceListValidity(

int deviceListValidity)

uwp

async Task SetDeviceListValidity(

int deviceListValidity)

SetDeviceListValidity(

deviceListValidity)

php

function ySetDeviceListValidity(

$deviceListValidity)

async SetDeviceListValidity(

deviceListValidity)

By default, the library performs a full enumeration every 10 seconds. To reduce network traffic, you can increase this delay. It's particularly useful when a YoctoHub is connected to the GSM network where traffic is billed. This parameter doesn't impact modules connected by USB, nor the working of module arrival/removal callbacks. Note: you must call this function after yInitAPI.

Parameters :

deviceListValidity nubmer of seconds between each enumeration.

YAPI.SetHTTPCallbackCacheDir()
YAPI.SetHTTPCallbackCacheDir()ySetHTTPCallbackCacheDir()

Enables the HTTP callback cache.

php

function ySetHTTPCallbackCacheDir(

$str_directory)

When enabled, this cache reduces the quantity of data sent to the PHP script by 50% to 70%. To enable this cache, the method ySetHTTPCallbackCacheDir() must be called before any call to yRegisterHub(). This method takes in parameter the path of the directory used for saving data between each callback. This folder must exist and the PHP script needs to have write access to it. It is recommended to use a folder that is not published on the Web server since the library will save some data of Yoctopuce devices into this folder.

Note: This feature is supported by YoctoHub and VirtualHub since version 27750.

Parameters :

str_directory the path of the folder that will be used as cache.

Returns :

nothing.

On failure, throws an exception.

YAPI.SetNetworkTimeout()
YAPI.SetNetworkTimeout()ySetNetworkTimeout()[YAPI SetNetworkTimeout: ]ySetNetworkTimeout()ySetNetworkTimeout()YAPI.SetNetworkTimeout()YAPI.SetNetworkTimeout()YAPI.SetNetworkTimeout()YAPI.SetNetworkTimeout()ySetNetworkTimeout()YAPI.SetNetworkTimeout()YAPI.SetNetworkTimeout()YAPI.SetNetworkTimeout()

Modifies the network connection delay for yRegisterHub() and yUpdateDeviceList().

cpp

static void ySetNetworkTimeout(

int networkMsTimeout)

+(void) SetNetworkTimeout

: (int) networkMsTimeout

pas

ySetNetworkTimeout(

networkMsTimeout: LongInt)

procedure ySetNetworkTimeout(

ByVal networkMsTimeout As Integer)

void SetNetworkTimeout(

int networkMsTimeout)

java

void SetNetworkTimeout(

int networkMsTimeout)

uwp

async Task SetNetworkTimeout(

int networkMsTimeout)

SetNetworkTimeout(

networkMsTimeout)

php

function ySetNetworkTimeout(

$networkMsTimeout)

async SetNetworkTimeout(

networkMsTimeout)

dnp

static void SetNetworkTimeout(

int networkMsTimeout)

static void SetNetworkTimeout(

int networkMsTimeout)

This delay impacts only the YoctoHubs and VirtualHub which are accessible through the network. By default, this delay is of 20000 milliseconds, but depending or you network you may want to change this delay, gor example if your network infrastructure is based on a GSM connection.

Parameters :

networkMsTimeout the network connection delay in milliseconds.

YAPI.SetTimeout()
YAPI.SetTimeout()ySetTimeout()YAPI.SetTimeout()

Invoke the specified callback function after a given timeout.

function ySetTimeout(

callback, ms_timeout, args)

SetTimeout(

callback, ms_timeout, args)

This function behaves more or less like Javascript setTimeout, but during the waiting time, it will call yHandleEvents and yUpdateDeviceList periodically, in order to keep the API up-to-date with current devices.

Parameters :

callback	the function to call after the timeout occurs. On Microsoft Internet Explorer, the callback must be provided as a string to be evaluated.
ms_timeout	an integer corresponding to the duration of the timeout, in milliseconds.
args	additional arguments to be passed to the callback function can be provided, if needed (not supported on Microsoft Internet Explorer).

Returns :

YAPI_SUCCESS when the call succeeds.

On failure, throws an exception or returns a negative error code.

YAPI.SetUSBPacketAckMs()
YAPI.SetUSBPacketAckMs()YAPI.SetUSBPacketAckMs()

Enables the acknowledge of every USB packet received by the Yoctopuce library.

java

void SetUSBPacketAckMs(

int pktAckDelay)

This function allows the library to run on Android phones that tend to loose USB packets. By default, this feature is disabled because it doubles the number of packets sent and slows down the API considerably. Therefore, the acknowledge of incoming USB packets should only be enabled on phones or tablets that loose USB packets. A delay of 50 milliseconds is generally enough. In case of doubt, contact Yoctopuce support. To disable USB packets acknowledge, call this function with the value 0. Note: this feature is only available on Android.

Parameters :

resend the last USB packet.

pktAckDelay then number of milliseconds before the module

YAPI.Sleep()
YAPI.Sleep()ySleep()ySleep()[YAPI Sleep: ]ySleep()ySleep()YAPI.Sleep()YAPI.Sleep()YAPI.Sleep()YAPI.Sleep()ySleep()YAPI.Sleep()

Pauses the execution flow for a specified duration.

function ySleep(

ms_duration, errmsg)

cpp

YRETCODE ySleep(

unsigned ms_duration, string errmsg)

+(YRETCODE) Sleep

:(unsigned) ms_duration :(NSError **) errmsg

pas

integer ySleep(

ms_duration: integer, var errmsg: string): integer

vb	function ySleep(	ByVal ms_duration As Integer,
		ByRef errmsg As String) As Integer

static int Sleep(

int ms_duration, ref string errmsg)

java

int Sleep(

long ms_duration)

uwp

async Task<int> Sleep(

ulong ms_duration)

Sleep(

ms_duration, errmsg=None)

php

function ySleep(

$ms_duration, &$errmsg)

async Sleep(

ms_duration, errmsg)

This function implements a passive waiting loop, meaning that it does not consume CPU cycles significantly. The processor is left available for other threads and processes. During the pause, the library nevertheless reads from time to time information from the Yoctopuce modules by calling yHandleEvents(), in order to stay up-to-date.

This function may signal an error in case there is a communication problem while contacting a module.

Parameters :

ms_duration	an integer corresponding to the duration of the pause, in milliseconds.
errmsg	a string passed by reference to receive any error message.

Returns :

YAPI_SUCCESS when the call succeeds.

On failure, throws an exception or returns a negative error code.

YAPI.TestHub()
YAPI.TestHub()yTestHub()[YAPI TestHub: ]yTestHub()yTestHub()YAPI.TestHub()YAPI.TestHub()YAPI.TestHub()YAPI.TestHub()yTestHub()YAPI.TestHub()YAPI.TestHub()YAPI.TestHub()

Test if the hub is reachable.

cpp

YRETCODE yTestHub(

string url, int mstimeout, string errmsg)

m	+(YRETCODE) TestHub	: (NSString*) url
		: (int) mstimeout
		: (NSError**) errmsg

pas	integer yTestHub(	url: string,
		mstimeout: integer,
		var errmsg: string): integer

vb	function yTestHub(	ByVal url As String,
		ByVal mstimeout As Integer,
		ByRef errmsg As String) As Integer

static int TestHub(

string url, int mstimeout, ref string errmsg)

java

int TestHub(

String url, int mstimeout)

uwp

async Task<int> TestHub(

string url, uint mstimeout)

TestHub(

url, mstimeout, errmsg=None)

php

function yTestHub(

$url, $mstimeout, &$errmsg)

async TestHub(

url, mstimeout, errmsg)

dnp

static string TestHub(

string url, int mstimeout)

static string TestHub(

string,