Chapter 4. CPU module
4 - 30
4.5.2 Self-diagnosis
1) Functions
(1) The self-diagnosis function permits the CPU module to detect its own errors.
(2) Self-diagnosis is carried out when the PLC power supply is turned on and when an error occurs the
PLC is in the RUN state. If an error is detected, the system stops operation to prevent faulty PLC
operation.
2) Error flag
If an error occurs, it will be stored to the following flags and the STOP LED flickers.
•
Representative system error flag : _CNT_ER
•
Representative system warning flag : _CNF_WAR
REMARK
1) Refer to 12.5 Error Code List of Chapter 12. Troubleshooting for details of contents of self-diagnosis
and corrective actions.