Mitsubishi Electric · MELSEC System Q/L Series
The work area RAM in the CPU module, or the standard and extended RAM areas, are faulty. This diagnostic occurs at power ON, after a reset, or when an END instruction is executed.
Click steps to track your progress.
Measure the incoming supply voltage to the PLC's power supply module and verify it adheres to the specified voltage range.
Inspect the CPU module to ensure it is correctly and securely seated in its base unit; re-seat the module firmly if any looseness is detected.
Verify the status of the CPU module's backup battery (if present) using its status indicators, and measure its voltage if safely accessible and within specification.
Inspect the CPU module, its base unit connector, and the backplane for any signs of physical damage, corrosion, or foreign material.
Verify that the operating environment's temperature and humidity are within the specified limits for the MELSEC Q/L Series system.