How to clear faults in Micrologix 1400 PLC

How to detect a faulty PLC

PLC’s are used in many industrial applications and these PLC’s would be connected to machines. We can detect if a PLC is working or not by checking the machine if the machine is not working then there is a good chance that it is because of a faulty PLC so open the PLC cabinet then we could determine if it is faulty or not so when a PLC is faulty it will shut down all output. In the below image a PLC is shown and there is a fault indicator section and if the PLC is faulty then it will flicker.

How to clear math overflow trap faults in a PLC by using Rslogix500

The faults in a PLC can be cleared by using an RSlogix500

The first step is to open the RSlogix network and check if the PLC address, it means that we can see the PLC’s IP address in RSlogix. If not we must create a network and by doing this we can check for the PLC in RSlogix.

  • In order to find the fault we can upload the program and can detect the fault.
  • Select Comms in your Rslogix and click the section that shows who active to go online now. By doing so a box will appear and we must check for our PLC’s IP address. The IP address will only be shown if there is a network, if not it won’t so we must create a network if the IP address is not in the Rslogix
  • Select the PLC’s IP address and click OK by doing so the PLC program will appear on the screen.


  • In this program it will show faulted because it is faulty click the faulted icon and we can see the above image. We can select go to error or clear faults while clicking clear faults, sometimes the faults could be cleared. If not go to clear fault section
  • Click the clear fault tab and by doing so a data table file would appear on the screen and there is a tab called error and sometimes it would give the error description.
  • We can check the error in the program and here it is a math overflow trap and it can be caused by giving a value that is higher than the RSlogix500 can count so we can edit it and clear the fault.

How to reset the acc/dec faults on Micrologix 1400

In the above image, we can see a micrologix1400 and there is an ESC button in the right side of the PLC click it and select the mode switch by using the arrow button, after that select the program and run.

How to reset the fault alarm in the Micrologix 1400

If the fault is really small then it could reset by switching the mode through the display and this step could also be helpful to clear the major faults too.

  • Select the advance setting in the display after that enter
  • Select the fault code and write it down, after that go to the main display
  • Select the mode switch and switch the remote mode after that select the program mode and enter.
  • After that select the run mode and by doing this the faults could be cleared.

How to clear an error code in Micrologix 1400

  • Go to the main menu by pressing ECS button
  • Then go to the advanced settings by clicking the down arrow button in the PLC and select it
  • Then by using the down arrow button select the fault code
  • So we can see the error code and the error code will be a four-digit the first two-digit shows where the error is generated from.
  • By checking the error code we could detect the error in the PLC, we must check the PLC instruction to determine the error code
  • So the error could be from one of the cards that are connected to the PLC, this card can be replaced and the fault can be cleared.