A: For IVC1S/IVC1L series PLCs

The power-off data of this series of PLCs is stored in permanent storage media, eliminating the need for a backup battery, and the storage scope is set in the system block (supports M and D components). 

When "data cannot be saved due to power failure, Memory error fault" occurs 

Steps to resolve the issue:
1. Check the "Power-off Save Range" setting in the system block to confirm that the M and D components to be saved have been included in the set range without omission;
2. Re-download the program and system blocks, write test data, power off and let it stand for 3 - 5 minutes, then restart, and check if the Memory error still appears;
3. If the error persists and data cannot be saved, it indicates that the permanent storage chip inside the PLC is damaged (not a setting issue), and the PLC unit needs to be replaced; it cannot be repaired by adjusting the program.

For IVC2/IVC3/IVC5 series PLCs

PLCs in this series rely on backup batteries to save data during power outages, and battery malfunctions can directly lead to data loss and error reporting. 

Steps to resolve the issue:
1. Prioritize checking the status of backup batteries and promptly replace failed batteries (to avoid data loss and error reporting caused by battery issues);
2. Confirm that the setting of "Power-off Save Range" in the system block is correct (the two sets of settings have no conflicts and are in a union relationship), to avoid data loss caused by incorrect range settings;
3. Re-download the program and system blocks, write test data, and perform a power-off test on the save function;
4. If an error still occurs after replacing the battery and resetting, it indicates a hardware failure in the internal storage, and professional personnel should be contacted for repair or PLC replacement.