Personal Computers Lose the Pretty Face

PC-based control gains acceptance with new and more practical form factors

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One of the main problem areas has been the Windows operating system. Desktop Windows is primarily designed for non-real time and non-critical applications. Earlier versions of Windows (prior to NT) were especially plagued by unexplained glitches, the blue screen of death, and frequent re-boots.

As detailed in our May 2002 cover story, this problem has largely been alleviated by the use of real-time PC-based operating systems. In addition to the various embedded versions of Windows, such as CE and embedded XP, real-time PC operating systems are also available in Linux. Firms such as VxWorks (, QNX (, and LynxOS ( also offer rock-solid real-time operating systems.

Table II: Industrial Grade PCs vs. Office PCs

Features to consider

Industrial Grade

Office Grade

Can it withstand extended temperatures?



Can it withstand shock & vibration?



Is it dust proof, or does it have filtering?



Is it splash proof?



Does it have RFI/EMI shielding?



Does it have power surge protection?



What type of chassis construction?

Cold rolled steel, rigid

Flimsy, often plastic

Does it meet industry classifications?

NEMA/IP, MIL, etc.


What type of security does it provide?

Locking doors & drive bays


How much lifecycle technical support?

3-5 years

6-12 months

Does it provide Intrinsic Safety?



Mean Time Between Failure Data

Sometimes provided

Not provided

Mean Time to Repair

5-15 minutes

1-2 hours plus

Mounting & enclosures

Multiple Options

desktop or tower style

Is it fault tolerant?




How reliable are these systems? The control engine for Westinghouse's Ovation DCS ( is the VxWorks operating system running on dual redundant PCs. Ovation DCSs are used to control power and water/wastewater plants worldwide with some systems controlling over 10,000 I/O. The VxWorks operating system also is used to control the NASA Mars rover. The QNX operating system is used to control robot hands in surgical applications.

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