@tomas
Hi, thank you very much for your great tutorial. The board lives, and works well. I start to understand how to work with addresses. Previously I made the mistake of creating one group and trying to express all the relays with data points. Now I know it was nonsense. Thanks again very much. :-)

The point is that I can not map the registers. I have created a channel, created device (communication set up) and then a device created group. And then I want to add data points. And here I get lost, I read all available manuals from UniPi, but from the enclosed manual to the device I am not able to decipher what I should set. Such as ST Type, Offset Gap, Data Offset, Bit Offset, Multibyte Length. I play with Modbus for the first time and have been playing with it for 4 days and no progress. So I go for advice. Thanks a lot for any help.

Hi, for the third day I am trying to make a relay board that communicates via Modbus RTU. This is my first attempt with Modbus RTU. Of course I have a map of registers but I still fail. I have read all available manuals. Can someone help me, and according to the attached document help me set up Mervis? Thank you very much.!