Are fieldbus wars heating up again?

It seems the Fieldbus Wars may be heating up again. What's going on and how will it affect your plant and your plant's pocketbook? CONTROL Editor in Chief Walt Boyes provides analysis and commentary.

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 By Walt Boyes, Editor in Chief

R

ecent developments in the digital fieldbus space have us wondering if the “Great Fieldbus Wars” of the 1990s are going to flame up again. Emerson’s Martin Zielinski has been touring media hotspots with the latest on the EDDL standards. The HART Communications Foundation is piggybacking a new user-focused associate membership on the revitalization of the use of HART enabled instruments for asset management and calibration documentation requirements. ModbusTCP has received IEC acceptance as a standard, and the Siemens folks are the fount of a new public relations campaign to introduce Profinet as “the one and only fieldbus you will ever need.”

EDDL vs. FDT-DTM
The recent decision of Siemens to adopt the EDDL standard instead of the rival FDT-DTM standard for electronic device descriptions means that the majority of the large automation manufacturers have decided that EDDL is superior to FDT. Zielinski made the point that the most significant superiority issue is that FDT-DTM is operating system and software program dependent, while EDDL requires much less overhead to produce the same quality of API. (A copy of Zielinski’s white paper on EDDL, "EDDL: The Technology Behind Interoperability," is posted on ControlGlobal.com.) An FDT spokesperson, quoted in Andrew Bond’s Industrial Automation Insider, said that counting out FDT/DTM is premature, saying, “For your information, there will be a few other big names backing FDT in the coming months, so please do not believe all the ‘spin’ at the moment.”

Work-in-Progress Profinet
Profinet is being rolled out, according to Siemens, over the next few years, with machine control being the first of its functionalities to be offered. Process control with Profinet will await final refinement, and, says Siemens is not going to be available until early in 2006. The Siemens tactical marketing team CONTROL met with in November insists that Profinet for process control is not vaporware; it’s just not ready yet. Eventually, Profinet will absorb all other Profibus offshoots.

         



“One fieldbus to rule them all, and in the process, bind them.”


The HART Communications Foundation, previously a vendors-only club, has opened its doors to end users and others interested in furthering the use of HART in process automation. HART appears to be the little protocol that could, and has survived far longer with much more utility than its creators could ever have dreamed. Economically, with the large installed base of HART enabled instruments already wired for 4–20 mADC communications, it is difficult to argue with those, like the HART Plant of the Year, who are connecting their HART instruments to their control and asset management systems digitally, as well as communicating via analog channels. The relative differential in cost between so equipping a brown field plant and tearing out existing instruments to install a “more modern” fieldbus system makes it economically unsound to do so.

More Fieldbus Wars?
Siemens began a public relations campaign last month to introduce Profinet to North America. Their campaign sounded a little like “The Fellowship of the Ring” as they talked about “one network” to rule them all. Is this one of the first shots in a new Fieldbus War?

Not as such, says industry analyst Andrew Bond, “because there’s not a direct standards issue involved this time. In practice all Industrial Ethernet implementations can, in theory, coexist within the same implementation. So what we are going to see is probably what we should have had first time around—a straight fight to establish market supremacy.”

But what does that mean to the typical automation enduser? John Berra, CEO of Emerson Process Management, but wearing his Fieldbus Foundation Chairman hat says, “I don’t think there’s another war, but there will always be controversy. Unfortunately, many customers can’t sort this out, and so they stay away from really good technology.”

“I think the problem is and always has been confusing fieldbus for process with fieldbus for factory automation,” continues Andrew Bond, “and it's further confused when you add in Ethernet.”

Bond points out that Foundation Fieldbus is irrelevant in the Factory Automation market where the issue is Profibus vs. DeviceNet and ControlNet and now Profinet vs. Ethernet IP.  That one, he says, divides on Europe vs. North America lines (with the UK as ever trying to make its mind up in between).

Berra agrees. “Profibus is a world leader in discrete busses,” he says.

On the other hand in the process market, Bond points out,“especially oil & gas, refining and petrochem, Profibus is a non starter if you want to do control in the field because it doesn't support it.”

According to Bond, FF is the only game in town and that effectively shuts out Profinet as well. As for hybrids, as we've seen, people are quite happy to have Profibus DP for the non process part of the plant - controlling drives etc and FF for the process part.

“One fieldbus to rule them all is as much nonsense as Foundation fieldbus for factory automation,” Bond concludes.

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