Key things to consider before selecting a PLC

As we have been publishing recent articles related to the different control platforms that you can use in industrial automation projects, we must also take into account that there are factors that have an important weight when selecting a PLC as an automaton.

To begin with, the controller should meet your performance needs today, but keep in mind that the system may operate for the next five to 10 years. During this time, changes to the system may require modifications and choosing a flexible system in advance can help reduce costs in the future.

Second, consider what kind of support is available for your project, especially if you have questions about hardware or software. It can be frustrating and time-consuming if your PLC vendor does not provide in-depth support in a timely manner. Find out what kind of phone and local support you can take advantage of from the manufacturer. Make sure you feel comfortable with your access to help if needed.

Third, think about quality. Everyone wants to know that your system is reliable. Ask your supplier about the warranty. When sales trusts your quality, they back it up with long warranties.

And finally, consider cost. Today, every business, large or small, is looking for ways to be more cost-effective. When selecting a PLC, consider your total cost of ownership. You should always consider hardware and software costs, but think about ancillary costs. Are there annual software licence fees? Are there annual technical support fees? What is the cost of training? All of these costs can add significantly to the total cost of ownership of a PLC.

But beyond these first four considerations, before selecting a PLC for your automation project, the first thing to do is to define your goals and this can be done in four simple steps, or rather, by answering these four questions:

1. Do I want increased productivity, better repeatability, more consistent accuracy?
2. Do you need servomotors or stepper motors? Servo motors will generally have better acceleration and maximum speed characteristics than a stepper. Stepper motors work better at holding a position without hesitation.
3. What type of controller - will a PLC work or do you need a more dedicated motion and machine controller? For basic material and conveyor control, selecting a PLC is a good option. If high-speed electronic gearing, product registration or more complex motion is required, a dedicated motion/machine controller is a better option. If data handling is required, a more dedicated motion/machine controller would be better.
4. Will the controller do the job? It is best to specify a controller that can handle more control axes than you expect, as you may need to add these capabilities later. Make sure the controller has the processor power to perform all the necessary functions. It is common to "run out of gas" when performing multiple tasks simultaneously. Look for a fast processor, sufficient user memory, and plenty of connectivity.

While you're interested in selecting a PLC for your automation project, take a look at the 16 best practices for choosing the right controller for your automation project.

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