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Jan. 7, 2010
When COTS Isn't Good Enough: Industrial-Class Network Components Can Be a Better Choice in Certain Applications

By John Rezabek

A decade or so ago, our complex employed a locally legendary controls specialist who was unique in his fixation on nitpicking standard products that lacked some feature he insisted was indispensible. We'll call him Craig.

His co-workers, like me, derived a lot of entertainment from hearing the torment that sales reps experienced in their meetings with him. Craig was extremely knowledgeable and an unabashed instrumentation nerd whose penchant for revealing and deriding all the technical shortcomings of every rep and his or her products was relentless and nearly universally dreaded. Craig was a bit of a loner, so we'll never know whether he derived some pleasure from these floggings or simply felt he should extract some toll from those who asked for a bit of his time.

Curiously, Craig's efforts in the field were often devoid of the intensely demanding requirements he placed on vendors. An improviser, he rarely hesitated to leave convention behind.

One of his more infamous efforts used numerous, daisy-chained, six-outlet power strips to power single-loop controllers and recorders in an old panel. Fortunately for operations, Craig took a plant radio home and lived close enough to monitor the transmissions when he left work. It rarely took a phone call to get him out to the plant to troubleshoot and remedy a fault. To most of us, Craig's job-security obsession with being indispensible was a bit over the top.

Few of us don't value job security, especially these days, but an equally scarce number want to be so indispensible they can't take a vacation or leave the plant radio at work. Craig left us long before the widespread use of office-class Windows boxes and their associated network hardware became an everyday reality. But I wonder how many discount store hubs, routers and PCs we'd find had they been common in his day. For those of us who sometimes use COTS hardware in the plant, it's worth pondering whether we're setting ourselves up to be like Craig or leaving behind a scrambled hodgepodge for our successors. When a component fails, will you be able to troubleshoot it? Will the persons covering for you have a prayer of figuring out what you did?

A week or so ago in our plant, a Moxa access point we'd installed some time ago needed another portable device added to its list of allowed MAC addresses. The AP is managed through a password-protected HTML interface, and we soon realized no one remembered the password. Fortunately, Moxa's website still had the documentation available for download, and we were able to reset the switch and use the factory default password. Had this AP been a no-name generic from an online retailer, I suspect we might be replacing the whole thing right now.

"Environmentally hardened industrial Ethernet components are designed to provide the same lifespan as other automation components—typically 10–30 years or more," offers Bill Wotruba, director of connectivity products for Belden (www.belden.com). "By comparison, typical commercial-grade products for offices are designed for a 5-year average lifespan."
We discovered this when we shopped for a spare 3Com Superstack III switch for our DCS. We were a bit dismayed when we couldn't find a "new" one for sale anywhere—the offerings seemed to be eBay-like surplus and salvage retailers. The huge volume of COTS products makes them lower cost, but their commoditization also means a given model could be superseded rapidly.

When we use network hardware from a supplier whose main focus is industrial applications, we are much more likely to find its technical support friendly to the circumstances we encounter and get competent assistance with a product long after the person who installed it has left.

One of our OEMs determined a switch was needed for a local outdoor control panel last year and sent me a change order for a Hirschmann eight-port Ethernet switch. This little box cost a bit more than a comparable COTS offering but was built for service down to -40 °F, certified for Class I, Div. 2, hazardous atmospheres and DIN-rail mountable to save us from losing the device in the tangle of wire and cable on the floor of the cabinet or relying on double-faced industrial Velcro.

I'm impressed, and it's likely I'll be focusing on similar made-for-purpose industrial-class network devices for future applications.

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