Cause : Fieldbus communication interruption comes when the communication between the fieldbus module and the master (PLC) is interrupted.

A "CNF" fault in Schneider Electric drive indicate a "Communication Network Fault". This means the drive is unable to establish a connection with the network it's supposed to be communicating on.

1. Verify the communication settings on the devices (Drive, PLC, switches, repeater...).
2. Check for duplicate communication addresses.
3. Verify the environment (electromagnetic compatibility).
4. Verify the fieldbus wiring (continuity, cable type, grounding, and shielding).
5. Verify the terminating resistor.
6. Verify the timeout setting.
7. Replace the option module.