News and comment: Can WirelessHART and ISA100 converge?
After hearing a number of discussions on the topic of process device level wireless protocols at the ISA Expo last October, and the ARC Advisory Group Summit in February, it appeared to me that there was more heat than light being produced as groups hammer out their protocols and explore the possibilities of convergence.
It seemed that it might be useful to ask the WirelessHART folks what they hope to see from the convergence efforts, so I went to Emerson Process Management for an opinion on the topic. Emerson certainly has "skin in the game" in that it has been the leading vendor proponent of the protocol and was the first to begin selling actual products using WirelessHART.
(If you wonder why we’re offering a single view on the topic, bear in mind that we did the same for Honeywell in 2007, publishing an open letter from Jack Bolick , who was at that time the president of Honeywell Process Solutions . He advocated voting "no" on the WirelessHART protocol and gave his reasons why. We later followed with a response from the HART Communications Foundation .)
Here is Emerson’s suggested path to convergence between WirelessHART and ISA100 , as drafted by Peter Zornio, chief strategic officer for Emerson Process Management:
Emerson believes it is important and possible to both address end users demands for a single wireless standard for process automation and also preserve their significant investments in IEC 62591, WirelessHART products. In addition, Emerson would like to complete ISA100.11a by adding the key element that will make it interoperable. We believe that the best way to achieve convergence between WirelessHART and ISA100.11a is to create a Process Automation Application Profile for ISA1100.11a that incorporates the international standard IEC 62591, WirelessHART, as the Application Profile for process automation.
This approach meets the following requirements of end users:
• Allows convergence between the IEC 62591, WirelessHART global standard and the future ISA100.11a specification which is currently being revised. (A correction/corrigendum to the draft ISA100.11a specification is expected to be sent for vote in late 2010 or early 2011.)
• Protects their significant investment in WirelessHART products and leverages end user extremely positive experience of over 100 million hours of WirelessHART field device operation.
• Leverages the base of 26 million installed HART devices in customers facilities today by extending the use of existing tools and training.
• Allows ISA100.11a to achieve device interoperability.
• As it exists today, ISA100.11a is designed for but does not yet have any Application Profiles defined. In order to be interoperable among a wide variety of suppliers, ISA100.11a needs Application Profiles. Without an Application Profile, ISA100.11a is just a means to wirelessly transmit a message of digital data. There is nothing in the specification to specify how the collection of digital data can be interpreted. Adding a Process Automation Application Profile that is based on IEC 62591, WirelessHART ensures end users have a choice of an open and interoperable application layer supported by the 200+ member companies of HCF.
• The timeline to add a Process Automation Application Profile that is based on IEC 62591, WirelessHART aligns to the ISA100.11a Correction/Corrigendum timeline of Nov 30, 2010.
• The existing ISA100.11a draft is going to be revised because a number of issues were reported by an independently commissioned consultants hired by Shell. The current plan is to complete the revision of ISA100.11a by November 2010.
• Preserves ISA100.11a; other application profiles can be added at a later date.
Emerson is committed to working with ISA100 to address convergence between the IEC 62591, WirelessHART global standard and ISA100.11a.
Hopefully this will stimulate discussion and ultimately advance the convergence process.
-Peter Welander, process industries editor, PWelander@cfemedia.com
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