Meanings of the PLC Indicators

The meaning of the PLC indicator light usually includes the following.

(1) RUN indicator light:

Indicates that the PLC is running. If the RUN indicator is off, it means that the PLC has not started normally or has a fault.

(2) ERR indicator light:

Indicates that an error has occurred in the PLC, and corresponding troubleshooting and maintenance are required.

(3) PWR indicator light:

It means that the PLC has been powered on. If the PWR indicator light is off, it means that the PLC is not powered on or the power supply is faulty.

(4) COM indicator light:

Indicates the communication status between PLC and other devices. If the COM indicator is off, it means that there is a problem in the communication between PLC and other devices.

(5) IN/OUT indicator light:

Indicates the status of the PLC input and output module. If the IN/OUT indicator is off, it means that the input and output module is faulty or not connected correctly.

(6) BAT indicator light:

Indicates the status of the PLC backup battery. If the BAT indicator is off, it means that the backup battery is insufficient or the backup battery is faulty.

(7) TEST indicator light:

Indicates that the PLC is in the test mode. If the TEST indicator is off, it means that the PLC has not entered the test mode or there is a fault in the test mode.