Cause : Memory unit missing comes when no memory unit is attached to the control unit or the memory unit attached to the control unit is empty.

An FB11 fault in your ABB ACS880 drive indicates a critical issue: the drive is unable to detect a memory unit. The memory unit stores essential information for the drive's operation, including firmware and potentially application-specific settings. Without a properly connected and functioning memory unit, the drive cannot operate.

1. Power down the control unit.
2. Check that the memory unit is properly inserted into the control unit.
3. Power down the control unit.
4. Attach a memory unit (with the appropriate firmware) to the control unit.