Failed to Set 'Reboot at Powerfail' Parameter
ABB · System
What does E2-27 mean?
The CPU failed to set the 'Reboot at powerfail' parameter, which controls the system's behavior during power interruptions. This means the system might not restart correctly or automatically after a power failure, potentially requiring manual intervention to resume operation. This impacts system resilience.
Common Causes
- Parameter write protection enabled (e.g., via a DIP switch or software lock) on the CPU.
- Corrupted configuration area in the CPU's non-volatile memory preventing parameter storage.
- Firmware bug or insufficient permissions preventing the system from modifying core boot parameters.
- Power supply brownout during the attempt to write the parameter to persistent memory.
- Incorrect parameter index or value attempted for the 'Reboot at powerfail' setting (e.g., P0-05).
Repair Steps & Checklist
Click steps to track your progress.
- 1
1. Verify the physical write protection switch (e.g., SW1) on the CPU is in the 'Run' or 'Write Enabled' position.
- 2
2. Attempt to set the 'Reboot at powerfail' parameter (e.g., P0-05) via the engineering software.
- 3
3. Perform a controlled power cycle of the CPU by removing and reapplying 24VDC power.
- 4
4. Check the 24VDC power supply for stability and sufficient current capacity.
- 5
5. Re-flash the CPU firmware to ensure the operating system is not corrupted.