F0091 fault in WEG CFW500 Drive indicates an External Fault. This means a peripheral safety device connected to the digital inputs has opened, forcing the drive to shut down safely.
Cause:
- Wiring on digital inputs DI1 through DI8 is open or has poor contact.
Remedy:
Verify external cabling loops to the assigned digital inputs. Tighten loose screw terminals and check contact switches.
