Internal Error (SM560-S)

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.

• 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.

Click steps to track your progress.

1. 1

   1. Isolate and re-seat the SM560-S module in its backplane or mounting rail to ensure proper electrical contact.

2. 2

   2. Measure the 24VDC input voltage stability at the module's power terminals with a multimeter set to min/max recording.

3. 3

   3. Review the PLC diagnostics (e.g., 'Module Status' or 'Internal State') in the engineering software for more detailed clues.

4. 4

   4. Attempt a factory reset of the SM560-S module (if supported via software) followed by a program download.

5. 5

   5. Replace the SM560-S Safety PLC module if the internal error persists after these troubleshooting steps.