Stefan

Thank you. This indeed solves the problem. Perhaps 0 would be a better default value for the Base Addr (as it then follows the raw protocol communication as visualized e.g. by WireShark). But that is just an idea. Knowing now that this setting exists will help a lot. Thank you again!

I want to add (don't know how to edit this ticket). You can verify this with WireShark. Just send a request for registers with start adress x. And you see in WireShark that the modbus response will be returning registers starting at x-1.

Start address one too high.