Hey,
I am trying to communicate via modbus with an ABB B23 112-100. I use a RS485 to USB converter to connect to my laptop. With Modbus poll I simulate a master. Baud rate, address and parity are set the same.

Modbus Poll : Setup as follow:-
Serial port setup : COM 10 / 9600 / 8 / None / 1
Slave ID :1
Function : Read holding Register (4x)
Address : 5000
Quantity : 24
Scan Rate : 1000 ms

I always get the error message insufficient bytes received. Even when the B23 is not connectet to the RS485 to USB converter.
I would be very pleased to receive help.

 

What is the USB to RS-485 converter you're using? Does it have any type of "echo" settings on it that may be causing it to send each request character back to the laptop?

 

i fixed it. changed the wires and switched to a different converter.