National committees torpedo IEC 61158 in close vote
In a stunning though not unexpected rebuke, the International Electrotechnical Commission's national committees voted Sept. 30 not to publish IEC 61158 as an international fieldbus standard. National members narrowly rejected Final Draft International Standard (FDIS) documents covering IEC 61158's Data Link Layer (DLL) and the Application Layer (AL).
In a stunning though not unexpected rebuke, the International Electrotechnical Commission’s national committees voted Sept. 30 not to publish IEC 61158 as an international fieldbus standard. National members narrowly rejected Final Draft International Standard (FDIS) documents covering IEC 61158’s Data Link Layer (DLL) and the Application Layer (AL).
After more than a decade developing and seeking approval for IEC 61158, its supporters were extremely disappointed by this new setback. However, they vowed to strive on, and perhaps appeal the vote’s results shortly.
IEC 61158’s detractors were publicly restrained and privately jubilant following the vote. They say the ballot bolsters their criticisms of the proposed standard and will allow the market to decide between IEC 61158 and the standard they support, CENELEC EN 50170. IEC 61158 supporters say EN 50170 is actually three standards, not one.
“Rather than a ‘victory’ for any one technology, as some are claiming, the unsuccessful IEC ballot is really a setback for the world’s end-users, who are overwhelmingly in favor of establishing a single, international, interoperable fieldbus standard,” says John Pittman, president of the Fieldbus Foundation (FF, Austin, Tex.), one of IEC 61158’s main supporters. “It’s very unfortunate that Profibus International and its affiliates put so much effort into defeating a standard that is supported by a majority of the world’s national standards committees, virtually every major control system supplier, and an impressive list of end-users. How does this kind of activity serve the industry’s best interests?”
Mr. Pittman noted that more than 70% of the participating members of the SC65C committee, those most involved in developing IEC 61158’s specifications, voted in favor of the DLL and AL FDIS documents. “This fact casts considerable doubt on the unfounded claims by Profibus proponents of technical deficiencies in IEC 61158,” he says.
Mr. Pittman indicated there’s is an opportunity to appeal the ballot as part of IEC’s process, and that FF will continue to work for a single fieldbus standard. “The world’s end-user community can be assured that this battle is not over. We remain committed to an impartial standardization process that will bring consensus and resolution to the fieldbus issue,” he added. “End-users want, and deserve, nothing less.’
Some sources indicated there may even be an effort by one of the national committees to alter the voting rules to discount some of the latest negative votes. If this happens, it might be a turnabout similar to the disqualification of Brazil’s vote in favor of IEC 61158 earlier this year. That vote was later reinstated, allowing IEC 61158 to become a final draft.
“Profibus International remains one of the strongest supporters of international standardization. However, we had major concerns about the quality of the proposed IEC 61158 documents. With the exception of the Physical Layer, which is used by Profibus, we’ve always felt that the remainder of IEC 61158 was far too generic and, in some cases, behind the times,” says Mike Bryant, deputy director of Profibus International (PI, Karlsruhe, Germany) and executive director of the Profibus Trade Organization (PTO, Phoenix, Ariz.). “The whole idea of IEC 61158 is questionable because, instead of having the three-headed monster of EN 50170, we’d end up with the even more multi-headed monster of IEC 61158. We’re gratified that enough voters took the time to examine the proposed standard and see there were some deficiencies that couldn’t be corrected.”
Mr. Bryant added the recent vote gives IEC a chance to reconsider its strategy and implement the recommendations of the Sector Board 3, which include standardizing interfaces, and turning the documents into a Technical Report, allowing time for more work.
“If we had to adhere to IEC 61158, we’d have to change the silicon that all Profibus products in the field are based on,” says Mr Bryant. “No standard should ever be written which excludes a predominant technology. Let the marketplace decide.”
While market rule sounds fair (especially when you’re in the majority), leaving crucial decisions up to market forces may have an unexpected price. Without compromise and one agreed-to standard, manufacturers and users will likely continue a costly struggle that could have been far less expensive, time consuming, and confusing for end-users.
In addition, the growing popularity of Ethernet connections, open buses, and other communications systems may even make many of these struggles irrelevant. So, though it might be logical to protect short-term profits, less infighting now might have given today’s fieldbus developers the time needed to form a viable defense against other communication options that could consume the bickering parties’ markets.
Breakdown by national commitees
|**(Y=yes, N=no, A=abstention)|
IEC 61158 voting results
The following is a summary of International Electrotechnical Commission (Geneva, Switzerland) members votes ending Sept. 30 on the four-part proposal to publish IEC 61158 as an international fieldbus standard. National committee members voted on the proposed international fieldbus standard’s data link service definitions (65C/197/FDIS); data link protocol specifications (65C/198/FDIS); application layer service definition (65C/199/FDIS); and application protocol specification (65C/200/FDIS).
Each committee’s vote was the same for all four parts of IEC 61158, except for China, which voted against the data link service definitions (65C/197/FDIS) and in favor of the other three parts (see chart at right). A late vote from the Philippines on the application layer service definition (65C/199/FDIS) was not counted.
It should be noted that more than 67% of P (participating) members must vote in favor and no more than 25% of all votes cast can be against a proposed standard for it to be adopted. IEC documents say abstentions aren’t counted in favorable vote totals, but IEC rules did allow abstentions and O (observing) member votes to be used to calculate total percentages of votes against IEC 61158.
|*Data link service definitions (65C/197/FDIS)
**Data link protocol specifications(65C/198/FDIS), Application layer service definition (65C/199/FDIS), Application protocol specification (65C/200/FDIS)
Source: Control Engineering with data from the International Electrotechnical Commission, 1998
|P members voting:||25||26|
|Total votes cast:||33||34 or 36|
|P members in favor:||16 (64%)||17 (65%)|
|Total against:||11 (33%)||11 (32%)|