W
Watchdog Timer Error
Mitsubishi Electric · MELSEC iQ-R Motion Controller
What does W mean?
This error indicates a watchdog timer fault, where the system's watchdog mechanism has not been reset within its expected interval. This typically points to a software malfunction or an unresponsive process within the Motion CPU module, or a hardware error.
Common Causes
- Software malfunction causing the watchdog timer to expire
- Unresponsive process within the Motion CPU module
- Hardware error impacting watchdog timer operation
Repair Steps & Checklist
Click steps to track your progress.
- 1
Check the error cause with 'Motion CPU WDT error cause (SD512)' using MT Developer2 to diagnose the specific watchdog error.
- 2
Remove the identified error cause (e.g., correct program logic, optimize processing).
Verified technical data. Last updated: March 2026
Related Faults
Source: Mitsubishi Electric MELSEC iQ-R Motion Controller