What is a PLC?

A programmable logic controller (PLC) is the nervous system of an organization’s computer system that allows management and technicians to work better. It continuously makes decisions based on system inputs that increase equipment efficiency, production lines, and manufacturing processes. PLCs collect and share data so that teams have insight into what specific operations need to be adjusted or should remain the same. They are typically used to monitor motors or machines, often acting as the basis of a predictive maintenance approach to avoid unplanned breakdowns.

Types of PLCs

PLCs are typically compact or modular. Compact PLCs are better suited for small applications because they have a set number of input and output capabilities. However, if your organization is large or growing substantially, modular PLCs allow for customization and easier expansion of an overall system.

Key Components of a PLC

Regardless of the type of PLC, they all include common key components, including:

  • Inputs: PLCs gather information through various input devices. This may include sensor-generated data from specific equipment or manually entered data recorded from equipment by workers.
  • Outputs: Output devices include things like valves, lights, and relays. They function based on the interpretation of input data.
  • CPUs: Central processing units act as the brain of the PLC by evaluating input data and sending it to output devices based on pre-established rules.
  • Communications: A network of communication equipment and associated protocols enable data to flow throughout the organization’s systems.
  • HMI: Human-machine interfaces allow employees to directly interact with machines. A technician is able to review data, adjust inputs, manage outputs, and make related decisions using the HMI.

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How to maintain a PLC

PLCs are critical to the smooth operation of your factory, so it’s important that they remain running at peak efficiency. The best way to keep a PLC system properly functioning is with regular, preventive maintenance. PLC preventative maintenance tasks can save you money in repair bills and downtime. Below are a few suggested tasks you can add to your preventative maintenance checklist:

1. Calibrate analog components

The manufacturer of your PLC should provide an optimal preventative maintenance schedule for your analog input devices, so be sure to follow the guidelines for keeping your analog inputs clean and accurately calibrated.

2. Insulate from debris

There will always be a risk of your PLC being exposed to debris during regular operation. Debris might include corrosive and conductive contaminants that can damage the components of your PLC. Perform regular visual inspections of all input and output devices and look out for signs like black dust. Canned air can be used to blow debris away from the system when necessary.

3. Change filters

To prevent build up of debris and dust, change ventilation filters in any PLC enclosures. The frequency should be determined by environmental conditions and specific needs.

4. Replace worn-out parts

The input and output modules of a PLC are susceptible to general wear and tear. Be sure to follow the manufacturer’s instructions for when to repair or replace modules and how to do so properly.

5. Check environmental conditions

Environmental conditions like humidity levels and temperature can impact the proper functioning of a PLC’s components. Use sensors to help you monitor these conditions around the clock.

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