It took us some time to find a design that suited us, but this week we can finally announce the latest member of our family of USB analog interfaces: Here is the Yocto-0-10V-Tx.
Although communication protocols between electronic devices clearly move in the direction of digital solutions, analog communication solutions still dominate numerous activity areas, for cost reasons or simply for historical ones. The three main standards are:
- Pulse Width Modulation (PWM), used for example in power controllers. The Yocto-PWM-Rx and the Yocto-PWM-Tx enable you to interface these devices.
- Current loop transmission (4-20mA), often used by industrial sensors because they have a good tolerance to long lines of transmission. The Yocto-4-20mA-Rx and the Yocto-4-20mA-Tx are designed for this type of transmissions.
- Voltage transmission (0/1-10V), used by some sensors when accuracy is not essential, but which is also widely used in light controls. This is where the new Yocto-0-10V-Tx comes to meet the Yocto-0-10V-Rx.
A few controllers driven in 0-10V
The Yocto-0-10V-Tx can drive two appliances with inputs following the 0-10V standard. With a simple command, the Yocto-0-10V-Tx can produce an arbitrary voltage on each of the output terminals. It can also autonomously perform a linear transition between two specified values, by simply specifying the length of the transition in milliseconds.
The output voltage can be set with a resolution of 0.001V. The guaranteed absolute accuracy is 0.01V / 0.2% because of the fluctuation of the characteristics of some of the components, but the output is guaranteed by design to increase monotonically with the requested voltage, on the whole working range. You must be careful however with very low signals with voltage outputs: the command can not be able to reach the absolute zero, but be stuck at an inferior threshold in the vicinity of 5mV. This is why some systems use the 1-10V standard rather than the 0-10V one.
Isolation and power supply
The Yocto-0-10V-Tx is isolated: the USB interface is electrically isolated from the 0-10V outputs, which will help you avoid many bad surprises. There is however no need for an external power supply, as the outputs are powered by energy taken from the USB bus. The current available is however limited to 20mA per output. This device is therefore designed for producing a logical driving signal, not as a power supply.
The two outputs of the Yocto-0-10V-Tx are not electrically isolated from one another. If you connect two different devices to the Yocto-0-10V-Tx, make sure they share the same ground, or that they are themselves isolated.
Here is a short usage example of the Yocto-0-10V-Tx, to control two commercially available proportional led drivers. For this demo, we use a Yocto-RangeFinder to determine the position of the subject and the environment lighting is automatically adapted by a short Python program on Raspberry Pi: