Safety Systems Meet Automation

May 1, 2009
Manufacturing can be a dangerous undertaking.

Some processes use machines that can cut, grab or sever. Some processes use toxic chemicals as part of the recipe for making useful products. Some processes use or generate volatile gases or liquids that can cause large, devastating explosions. None of us want to be on the front page of a number of daily newspapers or the top hit on a Google search as a result of an accident.

Meanwhile, engineers have been diligently working during the past 20 years or so to automate manufacturing processes, which often adds complexity. Paradoxically, this technical complexity has had the common effect of simplifying the work of manufacturing. The result has been much more efficient and productive plants. Managers have the capability of quickly switching from among a diverse set of products in order to meet market demand and trump the competition. Three major underlying themes behind all of this have been networking, standards and integration.

Networks have proliferated into almost every aspect of manufacturing. And the networking technology of choice is Ethernet, in either its commercial form or in one of the several flavors developed specifically for manufacturing. Let’s take machine control as an example. Controllers may communicate with input/output devices via Ethernet in order to control the performance of the machine. The safety system is a separate, “hard wired” (meaning every point has its own wire running back to a master emergency stop relay) safety circuit. This is not only extra cost, but it ignores the many benefits of digital networks—for example diagnostic information. Understandably, engineers have been working diligently to bring networks up to standard in order to gain all the advantages of digital networks without sacrificing safety.

Standards are a conundrum—especially for safety. If your design meets the applicable safety standards, and then there is a problem, you can point to the standards compliance as part of your due diligence in designing a safe system. On the other hand, standards are not written in marble. And, there exist more than one standard. I asked Contributing Editor Alex Anderson to make sense of the applicable safety standards. It was the “Impossible Dream.” He has summarized them and added some expert commentary, but the gist is that standards can be confusing, but necessary.

Integrating safety and process controllers—or to what degree to integrate them—has been a hot topic for arguments for several years. Integration is apparently winning out in the market, but I’m sure I’ll get lots of letters from people who are not so sure it’s a good idea. But you can see the trends. Automation advances in other area are yielding benefits too large for safety engineers to ignore.

New standards work

Just as I was writing this, I learned from Mike Boudreaux, DeltaV SIS product marketing manager for Emerson Process Management, in Austin, Texas, that he and Bryan Singer, principal consulting engineer for Kenexis Security, in Columbus, Ohio, have instigated the formation of a new standards joint working group through the International Society of Automation (ISA). It’s ISA99 WG7, a joint working group (JWG) for ISA99 (security) and ISA84 (safety). Safety and security run parallel in many ways, and each can learn from the other.

How did I learn about this? Through Twitter ( Twitter is a “microblogging” tool where people broadcast short messages of 140 characters or less to those who follow them. Mike is @MikeBoudreaux, Bryan is @BryanLSinger, and, by the way, I’m @garymintchell. Another way to put this is,, and It’s just another way to have conversations on the Web. Sign up and follow us to join the conversation.

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