Internal Error (SM560-S)
ABB · AC500-S Safety Controller
What does E2-42 mean?
The SM560-S Safety PLC has encountered an unspecified internal error. This indicates a system malfunction that prevents normal operation and requires intervention.
Common Causes
- Unspecified internal hardware fault within the SM560-S, potentially specific to a certain subsystem.
- Corrupted boot firmware preventing proper initialization of the module.
- Internal watchdog timer timeout not explicitly linked to application cycle time.
- Power supply ripple or noise on the 24VDC line, causing erratic internal behavior.
- Degradation of internal components affecting critical timing or data integrity.
Repair Steps & Checklist
Click steps to track your progress.
- 1
1. Isolate and re-seat the SM560-S module in its backplane or mounting rail to ensure proper electrical contact.
- 2
2. Measure the 24VDC input voltage stability at the module's power terminals with a multimeter set to min/max recording.
- 3
3. Review the PLC diagnostics (e.g., 'Module Status' or 'Internal State') in the engineering software for more detailed clues.
- 4
4. Attempt a factory reset of the SM560-S module (if supported via software) followed by a program download.
- 5
5. Replace the SM560-S Safety PLC module if the internal error persists after these troubleshooting steps.