I have a similar problem, communicating with an ABB Drive though Modbus Serial (half Duplex). The wiring is correct, but I am unable of receive data.
I do not have errors, I just receive a number that does not make sense, and if I ask the value of the next register is that value +128 and so on and so for.
I am using Modbus library, anyone know what is the best solution to this problem?
I write without problem btw