Common faults and solutions in LG PLC maintenance

1. Compare the input signal
During LG plc maintenance, compare the status displayed by the LG plc programmer with the LED indication of the input module. If the results are different, then we should replace the input module. If it is found that there are multiple modules to be replaced, then, before replacing, we should check the I/O expansion cable and its connection.
2. If the LG PLC signal stops at one place, these places are usually the places where the output is stimulated, and are generally in an intermediate state. Then when the LG PLC is being repaired, we should look for the signal that causes its next operation to occur (timer, cable, input, drum controller, etc.), the programmer will display the on/off status of that signal.
3. During LG PLC maintenance, if the input state is consistent with the LED indication of the input module, then we need to compare the state of the input device (button, limit switch, etc.) with the light-emitting diode. If the two are not the same, we should measure the input module at this time. If a problem is found and the I/O device needs to be replaced, wiring or power supply must be done on site; otherwise, the input module needs to be replaced during LG PLC maintenance.
4. When LG PLC is being maintained, if the signal is a line, the output is different from the line or there is no output, then you have to use a programmer to check the output drive logic and check the program list. When repairing LG PLC, the inspection should be carried out from left to right, find out the first contact that is not connected, if the one that is not connected is the input, check the input point according to the second and third steps, if it is For Xianchuan, check according to steps 4 and 5. Be sure that leaving the master control relay does not affect logic operation.
5. When repairing LG PLC, if the signal is controlled by a counter, first check the logic of the control reset, and then check the counter signal, and proceed according to the above steps 2 to 5. Several methods for setting frequency converter There are: analog input setting, fixed frequency setting, communication input setting,.
6. During maintenance of LG PLC, if the signal is a timer and stops at a non-zero value less than 999.9, then the CPU module must be replaced.

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