00A12H
Failure of Disabling Safety Module
Mitsubishi Electric · MELSEC iQ-R I/O Module
What does 00A12H mean?
This event code is registered in the event history if the attempt to disable the safety module function of the I/O module with diagnostic functions fails. This means 'Enable (1)' remains in Validation status area (Un\G5377) and the ALM LED does not flash (400ms cycle), preventing normal operation.
Common Causes
- The attempt to disable the safety module function of the I/O module with diagnostic functions was unsuccessful.
- An incorrect value was set in Command area for module invalidation (Un\G5376) prior to the disable attempt.
Repair Steps & Checklist
Click steps to track your progress.
- 1
Check that the set value in Command area for module invalidation (Un\G5376) is correctly set to 1234H.
- 2
Turn on and off 'Operating condition setting request' (Y12) again.
- 3
Check Validation status area (Un\G5377) to confirm that 'Disable (0)' is now stored.
Verified technical data. Last updated: March 2026
Related Faults
Source: Mitsubishi Electric MELSEC iQ-R I/O Module