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

Here’s an inside look from some of the participants on the making of the first in an expected family of industrial wireless standards to be developed through the ISA/ANSI standards-making process.

Dave Gehman. Contributing Editor

Jul 3rd, 2009

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.

“有很多人提供意见，”供应商Honeywell Process Solutions的无线业务经理兼凤凰城委员会成员Dave Kaufman同意。“最终分析，最好的技术意见来自世界各地的专家。我对向我们提供的专家信息感到敬畏。”考夫曼补充说。“这些人没有说，‘如果您不这样做，这可能会发生什么，’那是，‘这就是将会发生的事情。这就是原因。’”

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.

从宝洁（P＆G）的角度来看，雷兹纳（Reizner）在较早的采访中谈到了相同的起点，标准化的动力相同：“我们是如何确定所需标准的？看看4-20 MA [有线]标准。它不仅定义了电流水平，还定义了从可互换的各种供应商制造系统和仪器所需的许多方面。”

“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.”

对于怀特黑德（Whitehead）来说，参与ISA100.11A的发展是“我第一次深入研究标准过程。作为较晚的细木工，我可以欣赏一切都不仅仅是多数共识的方式，而且我知道很多人为结果感到自豪。”

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查看工厂自动化，其中包括流程和离散制造的高速，较低延迟控制，” Whitehead解释说。“我们的主要目标是定义问题，不一定是定义解决方案。这样一来，一旦挑战被整理和优先考虑，最有能力进行技术创新的人将具有坚实的开发试金石。”

根据ISA, WG 16正在调查:无线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).

第一阶段（提案和论文的提交）于4月底公布。因此，该过程再次开始。

根据怀特海（Whitehead）的说法，每个新标准都会带来新的可能性。他说：“就无线应用程序而言，我们只是在冰山一角。随着标准的发展，越来越多的工程师将通过必要的基本信息毕业，越来越多的人将能够直接进行实施，而不是对问题空间感到困惑。当这种情况发生时，无线适用性将起飞，从现在起五年后，我们将从今天甚至没人能看到的申请中受益。”