At the dawn of the Age of Industrial Controls computers were programmed with punch cards in Fortran and programs were run in batch process. Computer hardware was the size of a small building and the heat generated required substantial air conditioning in order for the machine to operate. Massive, complex, expensive hardware that required a controlled environment to operate. Not practical for real world situations.
In order for the first Computer Numerical Control systems to be implemented the computer hardware had to be crafted specifically for the task, scaled down in size, and made rugged enough to operate in workshop environments, typically 90 degrees Farenheit with oil mist and debris in the atmosphere. Custom logic boards, primitive math engines and hand wound wire memory were the order of the day. Had it not been for the Navy’s ability to fund advanced manufacturing initiatives after World War 2, the entire CNC industry might have started elsewhere.
Fast forward 60 years to a hand held computer that costs less than what early calculators cost and which can outperform most laptops. With built in screen, microphone, camera, wireless interface, external hard drive support and cellphone communications capability.
If you haven’t noticed, the specs on your cellphone probably outperform the most powerful industrial controllers on the market in terms of compute capability. Load Linux OS on one of these processors and a generic PLC engine and you are ready for business.
Control systems exist based on what they do, not how they are made. When processors and memory were expensive, the solutions were limited. Other constraints on PLC hardware were the need to execute control programs emulating the behavior of actual relay panels. In the early days, the “if/then” behavior of relays was created by forcing the control system to update all inputs, then solve the logic, then set the outputs. Specific controllers for specific industries used unique hardware and programming solutions in order to create controls that worked in each field.
Cascading PID loops in a DCS are solved differently than sequential logic in a PLC. Multi-axis motion control is math intensive and must be solved at millisecond update rates in order to machine parts in CNC. But when processor power is infinitely faster and more powerful than the most demanding applications, everything changes. Lower cost means that the “intelligence” can be implemented in almost any product or process. High processing speeds mean that events and behaviors in the system under control must be understood much more thoroughly.
All of which is creating the worldwide acceleration in control technology that we are seeing today.