PLC Maintenance Tasks You Can’t Afford to Ignore

PLC Maintenance


Performing PLC maintenance is one of the most important things you can do to extend the life of your PLC and minimize the need for repairs or replacements. You can effectively avoid the costs for both of these things if you simply perform quarterly maintenance checks on your PLC.


What are some PLC maintenance tasks that you just can’t afford to ignore?


Check Analog Input

Checking analog input devices can ensure that they’re always in suitable calibration. Following your manufacturer’s schedule for preventative maintenance is something we recommend during your inspection along with the maintenance tasks we’ve suggested here.


During your inspection, you can rule out poor analog input modules by ensuring that the transmitter that’s hooked up to it is in good standing. Contacts on large contractors will need to be checked for output modules as well, and could do with a good cleaning, especially if under a heavy load.


Minimize Exposure to Contaminants

Let’s face it, your PLC has to work in some grimy places! The environment that your PLC operates in will ultimately affect its performance. Here’s how you can inspect and minimize their exposure to damaging contaminants:


  • Corrosive agents. Corrosive agents such as chlorine will degrade your components until eventually they just stop working. Is your PLC exposed to chlorine during operation? Check the cabinets of your components and check for signs of corrosion. A good cleaning never hurt anything!
  • Conductive contamination. Look for components that malfunction only on occasion – they could be exposed to conductive contamination by agents such as metal debris or carbon fibers. Seeing black dust? This is a sure sign that contamination has occurred and your components are likely affected.
  • Visually inspect components. Inspecting components can help you find evidence of damage during your maintenance routine. Canned air can help to gently clean these areas. Don’t forget to check the cabinet seal to ensure components are properly protected.


If your PLC operates in a harsh environment, it’s inevitable that damage will eventually occur. However, by performing these maintenance checks on your components, you can help keep your PLC clean and running smoothly. You can also be prepared with spares for when components do fail!


Ensure Connections Are Secure

You’d be surprised how many problems can be caused by loose connections. Checking them seems simple and mundane, but do it anyway. Your PLC maintenance routine should involve checking all connections and cables to ensure that they’re secure.


In cabinets that experience heavy vibration, you may need to check the cables and connections more often, or perhaps even install a vibration detector if you constantly experience problems. Checking the connections can save you time and keep your PLC running efficiently.


Check for Electromagnetic Interference (EMI)

When you’re working with big machines, you’ll likely have concerns about electromagnetic interference (EMI) due to high currents and voltages. Did you check for these when you had your PLC installed? Many times, PLC installations don’t account for EMI and how it can affect the performance of your PLC.


You may consider performing a wiring audit during your PLC maintenance routine. A wiring audit can help you find sources of EMI prior to any problems arising. Haywire analog signals could also account for EMI. Contactors on your output modules could be a source of HMI, especially as they age.


When communications get strange, EMI could be involved. Check all your other components before you consider EMI. A physical issue could also be causing symptoms of EMI.


Your PLC can work great and last for a long time when proper maintenance is done. Like any other machine, maintenance is an important part of proper operations. You can easily avoid downtime, repairs, or new parts simply by giving your PLC some TLC every few months!


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