Hi Marin G,

May I know your CP341 is configure as master or slave?

What is your part no for your CPU and CP341?
Do also note that:-
[software settings/setup]
1] if you are configuring as master ensure you have install the "CP PtP Modbus Master" software
2] if you are configuring as slaveensure you have install the "CP PtP Modbus Slave" software
3] ensure both CP341 and communication partyparameters settings are the same
e.g baud rate, stop bits, parity bit,etc

[hardware settings/setup]
1] the doggle license key need to be insert into the CP341 module
2] ensure your CP341 communication port pin assignmentare correct. i.eCP341 pin 4 is (+), pin 11 is (-) and pin 8 is (gnd).

Ensure the above setup are correct first. Then the next thing to check is yoursoftware logic.

I hope these will give you some help!

with regards,
how come