Automation Standards Are More Like Guidelines

Heads Up, Oysters! The Evolution of IEC 61131-3 and Other Undermined Standards Efforts Are Just Ongoing Misleading and Unhelpful Arguments by Industry Leaders

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Jim MontageBy Jim Montague, Executive Editor

Capitalism is a fantastically positive force that can enable trade and increase the economic utility and mutual well-being of all; that is, until a few million bad apples start to cut corners. Sadly, short-sighted and selfish business interests and their legislative puppets promise to serve their customers and fellow citizens honestly, but then rip them off for one-sided personal gain, and cloak their misdeeds in another round of conservative fiscal promises. These are tumors that Adam Smith's Invisible Hand is supposed to be able to purge from itself.

However, the flypaper of false promises, advertising, spin and other sleight-of-hand combine with semi-conscious customers, voters and other shellfish to make these lesions increasingly purge resistant. Consequently, the old Invisible Hand just can't seem to shake off these parasites, who patriotically sing its praises, and then do all they can to undermine it. No wonder vampires are so popular these days. 

Of course, the process control and automation field is far from immune to this disease. Technical misinformation, dishonest marketing, and products that do more to protect suppliers' market shares than serve customers' needs are longstanding hallmarks of manufacturing. More than 10 years ago, I thought it would be good to write an article comparing programmable logic controllers (PLCs) and other devices head-to-head, if only to make better sense of how one might serve a particular application better than another. What a greenhorn. Not only did I lack the technical resources to do it, but I found it's often impossible to research direct comparisons between control and instrumentation components because of slight, but significant and apparently unexplainable differences in their specifications and operating parameters. Sources at the time told me that many of these differences were unnecessary, and only seemed to be there to prevent comparisons with competing products. How nice.

And, don't even get me started on the long fieldbus squabbles and the resulting, eight-headed IEC 61158 non-standard standard. It was like watching a bunch of clowns arguing on a railroad track until the Ethernet Express came through and mowed them all down. Of course, a few of the more nimble acrobats survived by jumping on the bandwagon with their own Ethernet versions, which they've been using to dilute, I mean, make Ethernet rugged enough for the plant floor ever since.

"I weep for you," the Walrus said. "I deeply sympathize." With sobs and tears he sorted out those of the largest size, holding his pocket handkerchief before his streaming eyes. —Lewis Carroll, Through the Looking-Glass and What Alice Found There, 1872 .

One of the most unfortunate examples of these misleading and unhelpful arguments is the ongoing development of the IEC 61131-3 standard for programming PLCs. Introduced in 1993 and revised in 2003, its five parts include software rules for ladder logic diagrams, function block diagrams, structured text, instruction lists and sequential function chart.

However, many programmers, developers and users believe it too,is another non-standard because many of its rules are so generally stated, and because it allows so many exceptions and proprietary software extensions that its initial definitions and original promise of portability of software between devices is unfulfilled.

"I've maintained all along that I don't believe it is a standard as much as a guideline for vendor product development," says Jeremy Pollard. Our longtime "Embedded Intelligence" columnist in Control Design and contributor, has written extensively on the difficulties with 61131-3 and the benefits it can still provide. You can read all about it at www.controldesign.com/articles/2008/107.html.

Sadly, much of the evolution of 61131-3 and other undermined standards efforts reminds me of Capt. Barbossa in Pirates of the Caribbean. When talking about the pirates' "Code of the Brotherhood," he rolls his eyes and says, "Well, they're more like guidelines."

So, to any other oysters out there, I say be cautious around suppliers that want to help you with some standards, just as you should beware of weeping legislators and rattlesnakes. They're probably both working for bankers; all of them are hungry; and you look delicious.

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