The modern era of manufacturing is largely an outgrowth of controls. And that migration has had a long history since the relay logic and Computer Numerical Control systems of the 1950’s. (CNC for any younger readers that might not know what some of these crazy acronyms actually stand for). Would high speed automation of manufacturing be possible without control systems?
Probably not. And since all business is ultimately governed by return on investment, what are the implications on manufacturing processes when control systems cost in the tens of thousands of dollars as they did in the Seventies? Or over time, as the cost of control has decreased, are we justified in putting a controller on everything?
Is the alphabet soup of industrial control the basis of real distinctions in functionality? Or is it a matter of keeping the domain of a particular field of application in the hands of a few suppliers of proprietary solutions? In the early days, I think a lot of new control frontiers were driven by the demands of particular industries, Military and Aerospace applications of CNC’s where speed and precision were required, and high costs were acceptable. This stimulated the creation of a whole universe of equipment which, as with all things electronic, have become more affordable over time.
There’s the SCADA (sequential control and data acquisition) market that has been largely architected by the use of “loop controllers” and PID (proportional, derivative and integral) control models. In an early generation there were mainframe computers talking to remote hardware in process plant applications with huge wiring and infrastructure costs. The amount of time needed for the hardware to respond to changes in the process was a critical concern.
Scada applications seemed very different from PLC (programmable logic controllers) which were the electronic successor to the giant relay logic cabinets of the sixties and seventies. PLC’s promised the ability to do what relays did faster and cheaper and with programmability that would insure the systems were never obsolete. But the PLC’s kept getting faster and cheaper, so it became economically justifiable to replace and update them. And the ladder logic programming language that documented the labyrinth of relays is still the most popular language for programming control systems.
So it was a most peculiar event a few years ago when the new (at the time) Honeywell process controller platform was an Allen Bradley Contrologix. And now, (roughly) seven years later, Rockwell seeks to reinvent itself as a process control supplier.
So excuse me if I wax philosophical, but looking backwards, which you can never do except as you get older, its interesting to see that all the forms of control are based on relatively similar mathematical models of real world systems whose models execute on microprocessor based controllers. And our primary means of performance improvement is throw faster and faster processors at the problems. But processors just keep getting cheaper thanks to those magicians of silicon in the semiconductor industry. So is there a practical limit where the business opportunity is no longer profitable?
And looking forward, where are we headed? More and more applications are becoming data intensive. Many industries are able to solve the mechatronic challenges, control system challenges, but find their business governed more by the data system because of regulatory demands for traceability or the long term data needed to impact the precision of a critical process. Semiconductor, Pharmaceutical, Food and Beverage industry, Aerospace, you name it.
So is it a control system or a computer? What are the real differences? Reliability, speed, resistance to harsh operating conditions? In the early generations of CNC and PLC had very costly memory making data storage impractical. Hard disk drives today are offering 1Gigabyte of storage for 33 cents. So when is a control system a computer by another name? And where are we going over the next 5 to 10 years in the controls arena?
More to come.
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