How to Create a PLC Maintenance Checklist

Answered October 23 2020

PLC maintenance checklist

Programmable logic controllers (PLCs) are a critical part of the automation of manufacturing and other industrial-based companies. When PLCs fail, a business may experience expensive downtime due to the fact that procuring parts quickly can be a challenge. Establishing a regular PLC maintenance program and checklist can help minimize or eliminate that downtime by discovering potential issues before they cause major problems. 

Before You Begin

According to MRO Electric, it’s important to conduct some pre-maintenance tasks before beginning preventive maintenance on your PLC. Most importantly, be sure to back up your PLC program, so you have a current version in case anything goes wrong during the maintenance procedures. It’s important to keep project backups as well as a master in case files get corrupted during maintenance activities.

Once a backup is made, be sure to adhere to proper lockout procedures, shut down power to the unit, and take a complete inventory of all your parts.

What Tasks Should Be Included in a PLC Maintenance Checklist?

  • Environmental Conditions. Things like temperature and humidity can negatively affect your PLC components. Be sure that operating factors fall within safe ranges. You may consider investing in sensors that can monitor these factors on a 24/7 basis and send you alerts if ranges are exceeded.
  • Basic Housekeeping. Be sure to regularly remove dust and dirt buildup. This simple task can prevent your system from short-circuiting. Canned air can be an excellent tool to perform cleaning tasks easily.
  • Air Filters. Be sure to replace or wash air filters, so that your PLC can benefit from maximum air circulation.
  • Connections. Tighten all input and output module connections including communication cabins, sockets, plugs, and terminal strips. Connections are subject to loosening when vibrations are present. If this is your situation, you may want to invest in a vibration sensor.
  • I/O Devices. Be sure all devices are adjusted properly, especially analog devices that must be regularly calibrated.
  • Overall Condition. Visually inspect components for wear, discoloration, or burnt odors.
  • LED Indicators. These indicators are designed to be an easy way for you to know when you must replace the battery for your RAM memory module.
  • Scan and Error History. Check to see whether your system has generated any recent scanning or error histories. Find the root cause for these error reports.
  • Circuit Cards. Be sure these are calibrated twice a year with process control analogs.
  • Sensors. If you rely on sensors, be sure they are checked and maintained according to manufacturer instructions.
  • Electrical Flow. Address any power surges or shorts immediately. Have a backup power source on hand, and be sure to check its proper operation regularly as well.
  • EMI. Audit local wiring to identify potential sources of electromagnetic interference. Be sure wiring designs avoid close placement of lower-level components and high-current wires. That combination can result in static electricity issues that can be hard to resolve.
  • Other Equipment and Materials. Keep noise- or heat-producing equipment away from your PLC. In addition, remove things like drawings and manuals to ensure that they do not accidentally block air flow and result in overheating damage. However, you should keep the PLC close to the machine it’s controlling.
  • Update Requirements. Incorporate any product notices, recalls, patches, or upgrades into your maintenance plan.
  • Inventory and Plan for Replacement Parts. Since PLC parts can be difficult to acquire, especially for legacy systems, be sure you keep a stock of critical replacement parts. Record where they are located for faster access when needed.

Downloadable PLC Maintenance Checklist Template

We’ve created a template for you to use based on the recommendations in the previous section. Feel free to download and adjust as you see fit.

Download Template Here

How to Implement a PLC Maintenance Checklist

Although a simple written checklist may suffice for very small organizations with limited PLCs, medium- to large-sized companies may want to incorporate a PLC maintenance checklist into a computerized maintenance management system (CMMS). Having all maintenance checklists stored in one centralized location means that your maintenance technicians have consistent and complete information.

Depending on your equipment requirements, you may be able to schedule regular work orders that will appear automatically in a technician’s workload on a daily, weekly, or monthly basis. In addition, if you install sensor technology, you can program any discrepancies so that you’re immediately alerted when things like temperature, vibration, or humidity fall out of range.

Benefits of PLC Maintenance

Industrial companies that take PLC preventive maintenance seriously will reap many benefits. Here are just a few:

  • Lengthen Lifespan of PLC Equipment. Although manufacturers design PLCs to be quite durable and operate in harsh factory environments, adhering to a good maintenance program can extend the life of your PLC even further.
  • Increased Uptime. When a PLC goes down, it can affect your entire production line or critical pieces of equipment. This can result in expensive repairs as well as extended downtime to your production schedule.
  • Cost Savings. Besides reducing or eliminating the costs of downtime, you will also be able to drop other expenditures. For example, if you keep a small inventory of replacement parts, you will not be scrambling to pay overnight shipment costs or premium emergency repair bills.


PLCs play a vital role in the efficient and effective operation of today’s industrial facility. They receive important information from critical pieces of equipment and can help control outputs of different pieces of machinery.

Most PLCs are durable and well-designed, so they can be a dependable component of the modern factory. In order to keep them operating at their best, maintenance managers should create and execute a comprehensive preventive maintenance plan that includes a complete PLC checklist.

Doing so will help keep this critical component doing its job well, lengthen its lifespan, and, most importantly, keep your facility up and running smoothly and productively.

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