Behind the Transmitters: How ISA100.11a Nears Its Journey's End

What better time to revisit standards for industrial wireless applications than right now? The WirelessHart standard, published in September 2007 by the Hart Communication Foundation, and blessed by the International Electrotechnical Commission (IEC, as publicly available specification IEC/PAS 62591Ed. 1) exactly a year later, has moved into the industrial world (see “WirelessHart Moves Forward”). More recently, in April 2009, the International Society of Automation’s ISA100 Standards Committee on Wireless Systems for Automation voted to approve the ISA100.11a “Wireless Systems for Industrial Automation: Process Control and Related Applications” standard.

Some steps remain for ISA100.11a, which took the longest to arrive, but most of the hard work is over. Final comments gathered during the voting are going to be assessed, possibly resulting in some tweaks. Then, the ISA Standards and Practices Board must officially approve the standard, which is still technically a draft. According to those in the know, that could happen as soon as August of this year.

The follow-on steps will happen when the American National Standards Institute (ANSI) ratifies and publishes the standard, which could be relatively quickly. Plans are to take the standard global, so the IEC will duly deliberate, and in its own good time pronounce it yea or nay.

This business of making standards is a slow one, and time has indeed passed. ISA announced the formation of the ISA100.11 work group in May of 2006. Time is required to reach consensus around something that has hundreds, if not thousands, of technical details. April’s ISA100.11a yes-vote garnered 81 percent of the more than 600 voting members. Among these were 23 of the 24 end-user members.

 “Actually, while it’s an exciting announcement, looking back on the final vote, it was sort of a non-event,” says Cliff Whitehead, manager of strategic development at automation vendor Rockwell Automation Inc., Milwaukee, and an ISA100.11a committee member. “That doesn’t mean it was a foregone conclusion, but the previous ballot on the draft last October failed by only one vote. The changes that were made since that vote must have been pretty persuasive—65 percent voted ‘for’ in October, but this time, it was 80-plus percent.”

The dynamic nature of standards building is highlighted by this final, rolling record of agreement. Asked how consensus can prevail among technologists—who usually know their minds and are not quick to change them—Whitehead explains, “First of all, there is a detailed roadmap from ISA and ANSI that guides the whole process. It is essentially parliamentary procedure, which means that everyone theoretically has a chance to have his or her say.”

Whitehead delineated some of the procedural facets that helped smooth the process. First, the role of the leader of each work group was “less about participation and creation, and more about coordination. The objective was to hear all the sides of the issues—or at least, the biggest aspects—and maintain order.”

The concept? Let everyone have a say, and ideas find their own level. In reality, it does not work quite so smoothly, but eventually, rough edges are polished and the better concepts work their way to the top. Through it all, documentation and accountability help keep an even keel. “The leaders are kept accountable for steady progress,” Whitehead explains. “Participants were held accountable for good behavior as well. Everything was documented, and there was a very active Web site for work and document sharing.”

The latter was especially important because, as he says, “We all had our day jobs, and the personnel in attendance at any given meeting or teleconference could be different from the next get-together. We had to keep tabs on what had happened and what was on the table for discussion.”

The documentation itself, Whitehead says, was impressive. “The highly technical editors involved should take pride in their work. The tech committee, editors and authors really did their due diligence in going through literally thousands of comments from committee members, reviewers, vendors and users. The objective behind all the words and graphics was to set up a clear roadmap for equipment builders and end-users. Like everything else, this was and is an iterative process. We’ll see further revisions as everyone gets down to cases and uncovers areas that need more clarification.”

A rational process is fine, but perhaps more important was the basic technology and information gathered under the guidance and control of that process.

“There were many, many people who provided input,” agrees Dave Kaufman, wireless business manager for vendor Honeywell Process Solutions and fellow .11a committee member in Phoenix. “In the final analysis, the best technical input came from experts around the world. I’m absolutely in awe of the expert information presented to us,” Kaufman adds. “These people didn’t say, ‘Here’s what might happen if you don’t do thus-and-such,’ it was, ‘Here’s what will happen. And here’s why.’ ”

The expertise flowed from two primary sources. The first was technological information from people doing pure research—that is, from universities and think tanks. The second was from the cross-section of member companies. “You’d think we’d be at each others’ throats because we’re competitors,” Whitehead says, “but in the meetings, we basically acted as peer technologists trying to establish some common ground.”

Though end-users accounted for less than 5 percent of the total committee membership, their input held far more sway than the numbers would suggest. “The voice of the user was first-person in the ISA process, and that makes it unique,” Whitehead says. “Yes, you can argue that there’s user input when standards are created by vendor companies—vendors don’t make products in a vacuum, and most of them are trying to answer some real need or other—but there, the user voice is second-hand. We heard directly about the problems and challenges from people who focused directly on such issues as product quality and plant safety.”

One of the end-users on the ISA100.11a committee, Jim Reizner, a technology section head in corporate engineering at The Procter & Gamble Co., in Cincinnati, provided input on the end-user’s side of the process in an interview that took place a year ago. At that point, he said, “Most end-users are not shy about talking with vendors when problems happen.  What we are not so good at is being an active part of standards-making bodies to address challenges before they become issues.”

Reizner became part of the end-user initiative early in the ISA100.11a process. “My company was gracious enough to allow me to be a part of the process,” he said. His participation did provide give-and-take: “We knew that with participation, the standards would be developed in a way that met the specific needs and challenges of Procter & Gamble—something that might or might not happen without our involvement. Beyond this, by being a part of the development of these wireless standards, P&G is developing excellent first-hand knowledge of what the standards do and do not cover—the strengths and holes in the standards. This means P&G will be better able to quickly apply and appropriately leverage these wireless technologies as they become available.”

There was also a personal gain. “The last area of benefit—and perhaps most important for me—is the access I have to technology leaders in other end-user companies. During the development process, I was working day-to-day with people from Exxon-Mobil, Shell, Chevron, BP, Intel and many other companies. We were able to share learnings with one another in an open and informal way, thanks to our involvement.”

Given the difficulty and the time investment, way back at the beginning, there had to be some overriding force calling for the development of the standard. In talking about it, spokespersons returned again and again to the 4-to-20 milliAmp (4-20 mA) standard in wired automation controls.

In his earlier interview, Reizner talked about much the same beginning point, the same drive for standardization, from P&G's point of view: “How did we decide that standards were desirable? Take a look at the 4-20 mA [wired] standard. It defines a lot more than just electrical current levels—it defines a multitude of aspects required to make systems and instruments from various vendors interchangeable.”

 “Our focus was on a standard that provides performance commensurate with wired automation in a wireless world,” says Kaufman. “We were trying to keep everything, from data reliability to speed and usability, as close to wired as possible—to become the wireless 4-20 mA replacement. We think the result is possibly even better, because we had to account for the fact that a wire’s routing is completely under your control, but radio frequency signals can go to anyone with a receiver. So we had to create new layers of security.”

For Whitehead, participation in the development of ISA100.11a was “my first deep dive into the standards process. As a late joiner, I can appreciate the way everything resolved down to a more than majority consensus, and I know a lot of people take pride in the results.”

There must have been something compelling about the process: Whitehead is now co-chair of the ISA100 Working Group 16—like .11a, focused on industrial wireless, but now moving beyond process monitoring with 100 millisecond (ms) and slower response. Begun officially last November, it is known as the Factory Automation Working Group.

“WG 16 looks at factory automation that includes higher-speed, lower-latency control for both process and discrete manufacturing,” Whitehead explains. “Our primary objective is to define the problems, not necessarily to define the solutions. That way, once the challenges are codified and prioritized, the people most capable of technical innovation will have a solid touchstone for development.”

According to ISA, WG 16 is investigating: wireless sensing and/or actuating, possibly involving multiple hops; low latency in the range of 2-50 milliseconds; low power vs. line power trade-offs; security comparable to ISA100.11a; and leverage of existing technologies including hardware (chip sets) and software (communication protocols).

The first stage—submission of proposals and papers—closed at the end of April. With that, the process began all over again.

Every new standard brings new possibilities, according to Whitehead. “As far as wireless applications are concerned,” he says, “we’re only at the tip of the iceberg. As standards evolve, more engineers will be graduating with the necessary basic information, and more and more people will be able to move straight to implementation rather than puzzling over the problem space. When that happens, wireless applicability will take off, and five years from now, we’ll be benefiting from applications that nobody can even see today.”

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