waveshareIndustrial 8-Ch Analog Output Module, 12-Bit DA Conversion, Supports 8-Ch Simultaneous Voltage Output, DC 7~36V Wide Voltage Power Supply, Modbus RTU Protocol, Rail-Mount Support

This unit arrived with no documentation and I had to hunt it down online, and it wasn't as clear as I'd have liked. That said, I did get it working with a minimum of fuss.I was a little confused about what to expect from the voltage output since it says 0-10 volts but the device operates down to 7 volts. I didn't know if the output was going to be ratiometric to the supply voltage or what - turns out it's not. If you're running it on 7 volts, the maximum output will be about 7 volts but to get 7 you still enter 7000.

Out of the box there are no instructions, the instructions can be found on Waveshare's website. To make it simple: Out of the box the module is set up for 9600 8N1, Unit ID #1. Holding registers 40001-40008 are analog outputs 1-8, unsigned integers. Writing a value of 1 = 1mV. Write 1000 for 1V, and so on. Refer to the manual to change baud rate or device ID. Response is very quick, commanding the full 10v output from 0v results in an instantaneous jump to 10v. Output is very accurate. The device will hold the last commanded voltage, which for applications that only write when a change is made is ideal. Overall this is a great module, would definitely use their other offerings. It should include instructions though, searching the internet for instructions on a brand new device is a little frustrating.