Cause : FBA B communication comes when cyclical communication between drive and fieldbus adapter module B or between PLC and fieldbus adapter module B is lost.

The fault code 7520 in your ABB ACS880 drive indicates a communication fault between the drive and an external device connected through the Fieldbus interface (FBA). This fault specifically points to a communication break detection issue.

1. Check status of fieldbus communication.
2. Check settings of parameter group 50 Fieldbus adapter (FBA).
3. Check cable connections.
4. Check if communication master is able to communicate.