“A very nice bit of kit. It's always worth paying a bit more and buying Waveshare. The unit came well-packaged and with a UK PSU, not the US-EU one the listing mentions. The documentation on the Waveshare Wiki is first-class and, with the demo code, I was able to test the unit out in a matter of minutes. The demo code is also very useful for cut and paste to get your own code running. So far it has worked flawlessly so no complaints.”
“It's a decent Modbus relay but with one frustration which is worth mentioning. I wanted to use this with the 'minimalmodbus' python library in an application which included other RS485/modbus devices on a local network. The problem is that Waveshare have chosen command codes which don't correspond to the 'standard' set register write codes for modbus. This means that the Waveshare-specific commands are rejected by minimalmodbus as invalid. It's relatively easily solved by writing a dedicated Waveshare comms library, just a bit of a faff managing the two drivers on the same modbus to avoid collisions. All works fine though.”
