This is the same ol' argument about "My guy in a Red suit can beat your guy in a Blue suit".
What people seem to miss is that if you take off the suits, they're both just a couple of guys.
Each is capable of doing the same thing.
A CNC, PLC, and a PC are controlled by the same kind of critter... although there is no doubt that the PC is using the latest and greatest version of that critter.
I wonder if there are many PLC's out there still being controlled by the 8088 (or close to the 8088).
I wonder what the average age is of the CNC and PLC technology.
I know that NASA has a hard time moving away from that era of CPU... with good reason. I think that, maybe, the 8088 is the definition of "solid".
As I recall, the advent of a math co-processor is a relatively new thing for higher-end PLC's. (Some of you younger guys can't even relate to the idea of a processor without a co-processor... however, there was a time...)
Be that as it may...
The primary difference between the PLC and the PC is the "package" around the processor.
The "package" consists of harware components and software components.
You can go with either a PLC Manufacturer sanctioned package or you can build your own. If you go with a PLC Manufacturer sanctioned package then you are also using their software.
If you build your own, then you are not necessarily bound to one software package or another... you have access to a variety of packages. Those software packages are much more un-restricted in terms of their access to the processor (and co-processor) than the manufacturer-provided packages.
As always, this is good news for the Formula-1 Racer Mechanics, and not of much interest to the backyard-mechanic.
Depends on what you want...
However, in terms of what you can afford, there is a lot to be said for generally available, and reasonably priced, components and generally available, and reasonably priced, ways to control them.
Ultimately, the game is reliability. The PLC Manufacturers promise reliability. That is fine, until the particular component fails. Believe it or not, it happens!
Aside from DOA's (and soon to be almost-DOA's, regardless of why), all system-reliability depends on how equipment is used. This boils down to the developer and his skills.
Any idiot can design a piece of **** that is bound to fail. This can happen with PLC Manufacturer sanctioned components as well as generally available PC controlled componets.
The bottom-line is the skill of the developer... not the package delivered.
The DOW lost .52 this month!
The Red Sox, the Packers, the DOW... all of the superstitions are on our side, Tim!