Windows operating system on a PLC


Thread Starter

Anna M. Mercante

Can anyone tell me the advantages (or disadvantages) of utilizing Windows 2000 Professional vs. Windows XP on a PLC.

Anna M. Mercante
I am by no means an expert on operating systems and have only used XP to limited extent. I can however, tell you as a general rule of thumb that when Windows releases a new OS there are often software conflicts that aren't caught during beta testing. It was the same story when 2000 was first released, I had quite a few conflicts with early Windows 2000 and Siemens Step 7. If you are
set on using XP I would check with the tech support department of the particular PLC/Software manufacturer for any known conflicts before you


david mertens

The use of any windows operating system on a PLC is completely against the idea behind a PLC. A PLC is a computer to control real world hardware in real-time, preferrably with a fixed or at least a predictable scan rate. Windows is per
definition not a real time operating system and it defenitely doesn't have any fixed or even predictable scan rate. Besides a PLC doesn't need all the overhead of windows, it interacts with machines, not people so what use is a
window then?

E. Rodriguez

Since Windows XP recently became available, there might be some "quirks" that have not yet been addressed/discovered. This could lead to unexpected problems. In my opinion, I would use Windows 2000 Professional. Currenly, my
company's IT group is exploring Windows XP to see if they can identify any potential problems our engineers might encounter

Johan Bengtsson

Well, the first question is of course, are any of them really something you would like to run on a PLC?

Other than that I would probably go for W2k, mostly because it have been around longer and most of the problems are probably fixed by now. W2k is relatively stable compared to most other windows flavours, I don't really know about XP, but I think it is a little bit too early for most people to say anything about stability of XP yet.

When it comes to the task scheduler I suppose they both are equally bad (ie not something I would reccomend for a PLC) unless they have changed it in XP the scheduling resoulution is 16ms, effectively meaning no task could be reasonably scheduled better than approx 32ms. The task scheduler could be overriden by some extra add on giving you better real time characteristics and a higher resolution but plain windows isn't built for tasks like that. (This is not a fault - it is a design parameter and relatively well chosen for what the OS is supposed to do)

Then there are the part about activation in XP, could be a problem in your case.

/Johan Bengtsson

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Ranjan Acharya

I actually don't like either of the two since they are not modular, too general purpose and suffer from bloatware problems such as crashing, poor security et cetera. That point aside, NT 5 (aka 2000) is quite established and you should be able to get anything you want from "soft PLC" vendors for that. NT 5.1 (aka XP) is still a little bit new and not all the vendors have released a full suite of tools for XP yet. Also XP has a crazy product authorisation scheme that is not well suited to industrial control unless you have a thick skin, patience, deep pockets and access to unrestricted versions of XP that will let you go anywhere at anytime (I am not implying illegal activity here, just the ability to bring a back-up system on line without a VISA card and a free-phone / toll-free call to the beast of Redmond for your system that is not connected to the Internet). This will get the XP crowd going, but they have not given me a satisfactory guarantee that XP can easily "ghost" or "disk image" and work on not-identical back-up hardware or that the authorisation scheme is flexible enough for machine builders and so on. We always have a standard ghost image for our shop / field laptops that we install on top of new laptops as they arrive. The product authorisation scheme appears to nullify this since even though we have enough licences, we have to use a separate licence on each PC rather than just doing a restore. Perhaps this is just as easy as entering a new product authorisation code when we do the restore, perhaps not. In any case another hurdle as well as service packs (that require a re-boot), security releases (shouldn't this stuff be a little bit more secure before it is released), office software that cannot handle large documents and so on. Enough complaining for now. That's why we still use W2K.

There are also alternative platforms such as QNX, Unix, Linux et cetera that support "soft PLC" solutions with a little bit less baggage than big daddy from Redmond. There are always traditional PLCs too.


Jeremy Pollard

Why would you want to? Not enuff size in ROM, too slow, not real time (as such), most of the benefits (common drivers and DLL's) arent required by a PLC. The lsit could go on but.....
I'm sure will have lots of feedback:)

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Jeremy Pollard, CET
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After the simplicity and robustness of the PLC operating system, I cannot imagine why anyone would want to subject their control system to a Microsoft product.