Cause : DDCS controller comm loss comes when DDCS (fiber optic) communication between drive and external controller is lost.

The fault code 7581 in your ABB ACS880 drive indicates a DDCS controller communication loss. DDCS stands for Direct Drive Control System, which is a specific control mode offered by some ABB ACS880 models. This fault signifies a communication issue between the main control board of the drive and the external controller responsible for providing speed or torque commands in DDCS mode.

1. Check status of controller.
2. Check settings of parameter group 60 DDCS communication.
3. Check cable connections. If necessary, replace cables.