Cause : SERIAL 1 ERR comes when an issue with the drive's serial communication interface used for programming or connecting to external devices.

The F0028 code you're encountering is specific to the ABB ACS310 drive and indicates a serial 1 error. This fault code signifies an issue with the serial communication interface used for programming and parameter settings on the drive.

1. Check status of fieldbus communication. 
2. Check fault function parameter settings.
3. Check connections.
4. Check if master can communicate.