It seems like "dejavu". In the last couple of decades of the 20th century the big giant process instrumentation companies did battle to see who was going to be able to drive the standards for communication protocols. The big battles were between HART and Foundation Fieldbus that emanated out of the ISA SP50 committee. If memory serves me, HART had become a defacto standard long before the SP50 was finished with their work and the first commercial products were available. The fight between Emerson/Rosemount and Foxboro, Honeywell and others was a classic.... and the user was not served very well if you ask me. There are still three primary field instrument communication standards, e.g. HART, Foundation Fieldbus and Profibus. A recent research study reported that the first Fieldbus device was installed in 1997 and there are now almost 1.4 million Fieldbus devices installed around the world. However, this pales by comparison to HART. If you don't know how HART works, click here.
In his blog post from March 2007 Walt Boyes (editor of CONTROL magazine) estimated there were roughly 22 million HART devices installed. He also puts the Fieldbus device total closer to 500 or600 thousand. No matter, 22 million HART devices simply dominates the installed base of digitally connected devices. Another third party study indicates that HART represents 71% of process instruments purchased each year in North America with digital connectivity. It appears obvious that HART had become, and still is today, the defacto standard in wired digital protocols. That's important to understand because for small process instrument companies with limited resources we can focus in on the development and marketing of a single digital protocol and provide a marketable device that will meet the needs of a vast majority of the market. No matter how hard the HART opponents fought or how much money went into opposing HART, it is still the market leader. It may be decades before it is replaced as the leader. NO, I am not going to get into the argument of HART's disadvantages or advantages. YES, I know it is not technically a "fieldbus", but I am not claiming it to be..... it provides digital connectivity for process instruments.
So, what's happening with wireless? The same thing? Maybe. HART recently (September 7, 2007) formally announced the WirelessHART standard. The attacks began before the formal release and intensified in trade publications. However, check out the information about what WirelessHART can do at this web link.
The typical attacks against WirelessHART can be summed in the editorial written by Tim Bourke of Honeywell and published in the October/November issue of PETRO Industry News on pages 18 and 19. The summary of conclusions is that 1) not all bus standards will run on WirelessHART and 2) there is no case where WirelessHART will work that the ISA100 standard will not. Not a very convincing argument today for the small size process instrument company that can afford only a single implementation to drive and meet user demand.
However, there is a possible difference between how the wired standards were developed and handled and how the wireless standards seem to be emerging. At the recent ISA show last month it was decided, by HART foundation members and members of the ISA100 committee, that the ISA standard approach would work to integrate WirelessHART in its first release through a dual gateway architecture and then a more integrated approach in release 2. Maybe the pundits on both sides will behave differently this time. If so, the user will have a much better offering to look forward to. Time will tell. If not, we will likely see WirelessHART dominate the market of installed wireless connected instruments just as it does today for the wired digital connectivity.
Joe Lewis
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