ANSI ISA 100.11a Approval Stalled

Jan. 8, 2010
Dispute over appeals process derails process and may affect IEC acceptance.

Dispute over appeals process derails process and may affect IEC acceptance. Further convergence confusion as ISA 100.11a stumbles at ANSI while WirelessHART gets a boost from NAMUR.

Transformation of the recently approved ISA 100.11a standard for device level wireless networks in the process industries into an IEC standard, thought by many to be a formality and certainly presented as such at the Honeywell European User Group meeting in Lisbon in October, has suffered something of a set back with the failure of the American National Standards Institute (ANSI) to approve the new standard at its November meeting. Opinion seems divided as to whether ANSI approval is an absolutely necessary precondition for IEC acceptance, but the organization's role as the official U.S. representative to IEC makes it unlikely that the international body would give its approval so long as the relevant national body had reservations.


ANSI's concerns are understood to relate to the ISA 100 committee's handling of at least one of the appeals against last September's approval. It has been suggested in some quarters that one of the appeals was rejected without consideration on the grounds that it was submitted after the deadline for submissions, despite it being the committee's own delays in responding to the decision to appeal that had been responsible for the deadline being missed. How long ANSI might now take to resolve its concerns and accept ISA 100.11a as an ANSI standard is not known, but the suggestion is that it might take some time.

Nor is that the only apparent contradiction in the news of developments on the wireless standards issue given to the press in Lisbon. Readers may recall that much was made of the opinion expressed by Dick Caro, co-chair of the ISA 100.12 committee charged with converging the ISA 100.11a and WirelessHART standards, that the two are "inherently incompatible" and that a single standard "will never happen." That statement was not only alluded to a number of times in Honeywell EMEA sales support director Jean-Marie Alliet's Honeywell technology update, but the document was also presented on a slide in the presentation on the standard given by ISA 100.11a technical editor Rama Budampati.

Hardly surprisingly, given Caro's position as co-chair of ISA 100.12 and Budampati's role in ISA 100.11a, INSIDER and a number of other publications reported Caro's statement as the view of the committee. Not so, apparently. At least one publication, the U.K. magazine Process Engineering, received a distinctly frosty communication from Caro's fellow co-chair, Paul Sereiko. Process Engineering had quoted Alliet as saying that "The ISA100.12 committee concluded that the merger of the two technologies will not happen," which was a pretty fair if not exactly precise representation of what Caro had been quoted as saying in the document presented by Budampati. Sereiko, however, berated Process Engineering editor Patrick Raleigh for not verifying his sources, asserting that the "statement made is patently false.” What is even stranger is that he added that that he was not sure what the source of Alliet's information was, despite the fact that Alliet was, in effect, quoting his own fellow co-chair.

Recommended Practice

Sereiko then went on to set out what is actually occurring in ISA 100.12, which is pretty much as was reported by INSIDER in our last issue and indeed by Process Engineering: first the development of a Recommended Practice to be released in the first quarter of 2010 to enable field devices to be able to support either standard, the so called "dual boot" solution; second, the preparation of a white paper on coexistence of the two standards within the same facility and radio space; third, the preparation of a comparison document to enable users to query vendors during procurement.

It's in describing a longer term aim for this third document that Sereiko seems to part company with his fellow co-chair since, in his view, it will also "provide a starting point for technical teams from both the ISA100.11a camp and the WirelessHART camp to begin the arduous process of converging the two specifications.” Caro, on the other hand, it will be recalled, is quoted in the Budampati document as saying that "Both technologies are so different that I don't know of anybody who is interested in writing a standard that tries to put them together."

To judge by the mood at last month's Emerson Process Management presentation in the Netherlands, the issue of whether convergence between the two standards will or will not be achieved is being seen as increasingly irrelevant by the leadership of the Wireless HART camp, or at least by Emerson, which may or may not be the same thing. Indeed chief strategic officer, Peter Zornio, went so far as to say, "We don't talk about standards any more; we're past that point with WirelessHART," and added in support of that assertion that WirelessHART had passed the latest "IEC barriers” only the previous week.


The case for WirelessHART, at least as presented by Emerson, is that it has now achieved such momentum and has such a lead over its rival that it is inconceivable that ISA 100.11a can make up the lost ground. Point out, as does the ISA 100 camp and its chief cheer leader, Honeywell, that ISA 100.11a has major user representation, whereas WirelessHART has been developed solely by vendors, and Zornio simply sweeps the argument aside by pointing out the user support implicit in the 1000+ installations―"not just devices or gateways but complete installations”―which Emerson alone can claim to date. Moreover, he adds, "The world's number one DCS supplier, the world's number one device supplier and the world's number one valve supplier have all agreed on WirelessHART," although he conceded with a slightly sheepish smile that two of those are, of course, Emerson.

What about the ISA100 camp argument that ISA 100.11a is part of a much broader family of standards which will address almost every aspect of the use of wireless in process plant environments? It's a red herring, argues Zornio. It's only at the device network level that the unique requirements of the process industries have to be addressed, while the rest of the ISA 100 effort is essentially considering how those industries should adopt and adapt existing IT standards. Whether the field device level network is ISA 100.11a or WirelessHART is irrelevant to those higher level network functions, he suggests

Three words

What is absolutely critical now is the rate of adoption. Zornio argues that three words now sum up the field device network issue―"multi-vendor, interoperable and products.” Both standards can, or at least will be able to fulfil the first two, but it's the third that is now key. And while Emerson already has, arguably, the widest portfolio of wireless devices of any vendor, with the introduction of the HART Wireless Upgrade Module or THUM, it can now not only retrofit any existing wired HART device with wireless in the field, but "Every instrument we deliver can now be wireless." Moreover, he's anticipating a huge upsurge of installations as the industry, prompted by incidents such as Buncefield, appreciates how Emerson's newly introduced wireless valve position monitors have the potential to increase confidence and safety in applications such as tank farm automation.

As to the question of how support for the rival standards might best be achieved, Zornio says that Emerson's preference would be for "a dual mode gateway” rather than for Caro's "dual boot" solution. What he made clear was that the Emerson approach would be essentially pragmatic. Thus, when asked whether Emerson would ever offer ISA 100.11a-compliant products, he said, "We never say never.” If customers made it clear that they wanted them and "It's a big if," then Emerson would meet their needs.


One reason why Zornio doesn't think that's very likely, however, is the recent report produced by the German user organization NAMUR, which the HART Communications Foundation (HCF) has described as saying that WirelessHART technology meets the requirements for wireless sensor networks in process applications. The report is based on multi-vendor field tests at BASF's Ludwigshafen facility in Germany using products from ABB, Emerson, Endress+Hauser, MACTek, Pepperl+Fuchs and Siemens and designed to verify the technology's compliance with the NAMUR Recommendation NE124 on "Requirements for Wireless Automation" and its Working Document NA115 on "IT Security for Process Automation Systems." The HCF quotes Martin Schwibach, senior automation manager for BASF and chairman of the NAMUR working group responsible for the field test, as saying that "Our tests prove that WirelessHART is an appropriate technology for applications within the NAMUR use class ‘Monitoring' for wireless sensor networks. WirelessHART technology provides a good alternative where wired networks are too expensive or too difficult to install. This field test verified the alignment of the WirelessHART standard with the NAMUR requirements for wireless automation in process applications."

  • Vendors are still reluctant to go beyond recommending wireless for anything other than non-critical applications of which there are of course huge numbers potentially. However it's clear that, as Emerson's Peter Zornio put it, "Customers are doing serious applications," particularly now that full redundancy is available. Indeed the claim is that "WirelessHART is field-proven for control applications," supported by evidence that the response in wired and wireless applications is identical. But what about "Control in the Field (CIF)” over wireless? According Zornio, "We really haven't thought about it too much, since we haven't had any customers ask about it." However, Bob Karschnia, described by Zornio as Emerson's "head wireless guru," says that all of the basic building blocks for CIF are already in place in the HART7 specification of which WirelessHART is a part. Emerson has been doing long-time constant control using WirelessHART since it introduced the products, obtaining the input data from a sensor wirelessly and then passing it to the gateway and up to the DCS, where a control algorithm drives an output to a valve. "To do CIF, we will be upgrading our network manager (part of the gateway) in 2011 to allow for peer-to-peer communications to be scheduled ... This is only a software upgrade to our gateway, and no device upgrades are necessary. "
  • Reminding us that WirelessHART and ISA 100.11a are by no means the only wireless games in town, Prosoft Technology has announced release of its new RadioLinx intelligent cellular solutions, designed to provide wide-area and even global wireless connectivity for industrial devices. The Intelligent Cellular Gateways use the existing cellular infrastructure to connect devices across geographically diverse locations and can also connect devices through the Internet to one or more locations.

The solutions combine robust industrial cellular technology, industrial protocol templates and ALEOSTM software for persistent connection management, enabling real-time device status and health information including network connectivity, throughput and signal strength to be monitored. A further utility supports local or over-the-air device configuration and diagnostics while downloadable configuration templates support such protocols as DF1 and Modbus.

Editor's note: Control's editor in chief, Walt Boyes, is a party to the appeal in question, and has, therefore, recused himself from discussing or writing on the subject.