PLC maintenance does not execute the procedure:

In general, the output steps can be checked according to the input program

(1) The input check is identified by the input check LED indicator or checked by the input monitor composed of the writer. When entering. When the LED is not on, it can be preliminarily determined as an external input system fault, and then checked with a multimeter. If the output voltage is abnormal, it can be determined as the input module fault. When the LED is on and the internal structure monitor is not displayed, it can be regarded as the fault of the input module, CPU module or expansion unit.

(2) The PLC maintenance program is checked by the monitor in the writer. When the connection status of the ladder diagram is inconsistent with the result, the program error (such as dual use of internal relay, etc.). Or the operation part fails.

(3) The output check can be identified by the output LED indicator. When the operation result is correct, the output is correct. When the LED indicates an error, it can be considered that the CPU module and 1/0 interface module are faulty. When outputting. If the LED is on and there is no output, the output module fault or external load system fault can be judged.

In addition, due to different models of PLC, 1/0 and LED are connected in different ways (some are connected to 1/0 module interface, some are connected to 1/0 module). Therefore, according to different ways. The LED fault range is also different.