Patching and Upgrading PLC Systems

A certain well known vendor of PLC equipment has been earning some heat from me recently. I’m not mentioning names because frankly, all of these big name vendors are facing the same problems.

The issue is that even if we didn’t find sufficient reason to patch programs in a PLC, we’re finding that we have to upgrade processors and upgrade programs to new platforms at least once every five years. Our programming environments can’t continue to run on older versions of Windows.  The versions we use now are facing a looming deprecation date.

This places us in a terrible situation. We can have a choice of allowing our programs developed under an earlier version to continue on an unsupported OS and an unsupported firmware set, or we can upgrade a lot of things, and go through extensive, expensive testing to prove out a newer PLC processor that will work on a newer I/O controllers, newer peripheral cards and a newer OS with a newer development environment that might continue to have support for another five years.

At this rate, why are we dealing with the expensive vendors? There are cheap ones out there that will do the same things for literally about 20% of the price.  If we’re going to have to throw away so much hardware and do so much testing, what are we paying for?

Let me remind everyone, especially vendors: Patching, hardware upgrades, and testing cost far more than the product itself. We shouldn’t even need to patch in the first place. If you’re going to justify your higher prices and big dollar support contracts, be ready to explain what we get for all this effort, because right now, I’m having a very hard time explaining it to my leadership.

With more than 30 years experience at a large water/wastewater utility and extensive experience with control systems, substation design, SCADA, RF and microwave telecommunications, and work with various standards committees, Jake still feels like one of those proverbial blind men discovering an elephant. Jake is a Registered Professional Engineer of Control Systems. Note that this blog is Jake's opinion ONLY. No Employers, past or present were ever consulted with regard to these posts. These are Jake's notions. Don't blame anyone else for them.