If the future of the control industry could be compared to a weather report, it would have to be “fair to partly cloudy”. Figuring out what direction things are headed in is very to to predict with any clarity.
The first problem is what categories of control to consider. In the industrial arena the most common control is the programmable logic controller. Despite technological advances in the computer industry, the PLC continues to survive despite predictions of it’s demise. While various re-packagings of the personal computer have made great headway in recent years, and the soft PLC has emerged with significant market share, the PLC in a variety of forms continues to survive.
The PLC was born out of the need to create electrical control systems that exceeded the capabilities of the relay control systems they were modeled from. To make an orderly transition from the relay world to the transistor world, the common programming language of ladder electrical diagrams had to be converted to a software editor that would compile the ladder diagram described by the programmer. The processor and execution of the code could be anything, but the key ingredient was being able to program based on the descriptive language of ladder electrical diagrams.
The surprise here is how slowly the markets change. Perhaps the explanation is in the size of the market itself combined with the risk-averse nature of the users who put electronic controls in charge of every conceivable manufacturing process. The PLC market is in excess of $10Bil worldwide and if you add process control, motor speed controls, plant wide networking, motion control systems, well, you get the idea. This is really big business. These control systems serve in applications where the consequences of failures can be severe, sometimes catastrophic.
After 40+ years of application, the PLC continues to exist in many forms. From the pocket sized units from Panasonic that sell for less than $200 to the multiprocessor PC based PLC available from many suppliers like Beckhoff and Wago. However, what keeps these products on the market is their language. I remember many discussions of the merit of other programming languages like flowchart, C (and it’s variants), etc. At the end of the day, the massive installed base of equipment using ladder diagramming and the enormous number of people maintaining and using it continues to support the basic technology.
Not hardware driven, language driven. More on this next week.
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