Great to see your March 2014 piece on the PLC ("Live Wire," p. 17 ). Quite a statement. This is something I have been saying for some time, although coming from a slightly different context. I got dragged into a silicon start-up specializing in embedded motor control and got exposed to the power and cost of these devices. Five years ago it was possible to make a PLC work on a $6 processor with Ethernet already built into it.
The PLC may be on the verge of extinction as a hardware proposition. The fact that CoDeSys has pretty well co-oped the entire industry is nothing short of amazing. So now that the logic is software-based, there's not much market basis that will sustain hardware. The only thing that will endure is the need for I/O and the ability to host the application for the point of use. How that is implemented can be anything if the application is software-based.
The other thing to factor in is the ladder diagramming language. We've predicted the demise of ladder logic for decades. And it's still here with us. Too much installed base and no obvious replacement.
Manufacturers using the cloud? I don't think this is likely on individual machines. Plant network? Yeah. Corporate IT? Hell, yeah. Why pay for owning all that overhead if someone will host it for you for cheap?
Thanks for taking the risk to say it, I am impressed with your candor. The industry needs more honesty. Let's give it to them.
Solid Tech Inc.