40120000 hex
PLC Function Processing Error
Omron · NX-series CPU Unit
What does 40120000 hex mean?
A fatal error has been detected within the PLC Function Module, indicating a critical software malfunction. This error leads to a partial fault level. The user program will stop, and the controller operation will cease.
Common Causes
- An error occurred in the PLC Function Module software.
Repair Steps & Checklist
Click steps to track your progress.
- 1
Cycle the Controller power supply (turn OFF and then ON) to attempt recovery.
Verified technical data. Last updated: March 2026
Related Faults
Source: Omron NX-series CPU Unit