Remember that PLC control functions support "the process" on the factory floor. The ability for controllers to have comm ports to be remotely polled, and functions for timing/sequencing changed externally {and quickly} is a big factor in justifying their existence where cruder, mere hardwired electrical components might easily suffice and take a smaller bite out of the maintenance budget.
Some years back I did electrical training at a cutting-edge plant that had sole-sourced A-B 5/25-series systems when they were the first being offered with an ethernet interface. The firm paid a mint for the equipment and the programming, but thought that the potential realtime production-reporting capabilities would be the norm in the very near future.
VFDs and even plain-vanilla FVNR starters stock with hardened comm ports are becoming old news.
Several years ago I did some training in a very elegant old plant with only about a dozen PLCs, but each PLC cabinet had a piece of electrical tape on its stainless-steel door marked with its dotted-quad {IP} address. At that point, it was the plant lead electrician’s “crazy” idea that often went on the rear burner during most of an eight-hour shift. Ethernet connectivity and IP addresses for PLCs were though a silly novelty by many a dozen years ago.
It’s been “full steam ahead” from there. NEMA-4X Cat-V UTP [soon gigabit fiber] connectors would have been thought a completely ridiculous idea at that point.
Don't loose sight of the "60Hz side" of the picture. Do not forget that in most all cases electrical systems are there to support a mechanical process, and that microprocessors and just about everything else with 5-volt logic is there to support electromechanical components.
Plant machinery seems to be increasingly viewed by some as an incidental peripheral to the front-office {or corporate HQ half a continent over} datacomm/IT system. But electricians still need to know what safe actions to practice if a 4160V feeder trip isolates a section of the plant, regardless of the demands of some snot-nosed production administrator to “get it all moving yesterday.”
I wonder, in the whole scheme of things, if PCS phones really increase production and profits.
