Siemens alarm 431001: The safety mode of the F-PLC has been deactivated.
SINUMERIK PLC system alarm · Siemens 840D/810D powerline
What it means
The user deliberately switched off the safety mode of the fail-safe PLC; as a consequence certain automatic error-control measures of the F runtime are inactive. Siemens notes the condition is informational-plus-warning in nature and that the safety mode reactivates at the next PLC power-on. The machine must not be operated in applications relying on the deactivated F functions until then.
Likely causes
- Intentional deactivation during commissioning/testing of the F program
- Service personnel disabling F mode temporarily for diagnostics
Triage note: Clears/reactivates at next PLC power-on; program continuation switch control OFF - ON.
Need the part urgently?
Send us alarm 431001 with your machine details — typical RFQ turnaround is 24–48h.