Programmable logic controllers (PLCs) are complex pieces of equipment. If there is a vendor trying to tell you that a particular PLC will solve all of your challenges and is set to meet all of your needs, that is certainly a red flag. The truth is PLCs are much more complex by nature.
Manufacturers have been trying to achieve a common programming language through standards like IEC 61131. Even though the equipment works in a similar way, different manufacturers utilize different software. This software goes about tackling the challenges in different ways. With this in mind, one of the most important pieces of information when selecting a PLC is the ongoing support you’ll receive. There is always a learning curve with a PLC, despite the universal standard. Thus, ensuring that the support is going to be there is critical.
Although, some may wish for there to ultimately be program-less PLCs, but this desire would ultimately eliminate the PLC’s flexibility, which is one of its most attractive features. The more attainable and desirable goal, however, would be to achieve common programming among manufacturers. This would help simplify the programming from the end user’s perspective.
When every product has a different language, different programming philosophies and different needs, it becomes increasingly difficult to properly program them. We do, in fact, use something called Ladder Logic, which is a universal language for PLCs, but once we add in the element of motion control, differences occur.
The software development environment is another factor to consider. Just like comparing a Windows OS to a Mac OS, different programming environments facilitate different approaches. Although the controls are similar, the way they are implemented may be a bit different. As PLC manufacturers are always updating their products using the same language as previous versions but with new features, confusion can ensue.
Along with my colleague, Ray Marquiss, I wrote a comprehensive article on this topic for
Chemical Processing Magazine last year where we discuss this topic more in depth. I encourage you to check it out if you haven’t already.
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