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By Walt Boyes , Editor in Chief
Once again, dear end users, weíve handed you a mess. We, of course, are the members of the ISA100 Wireless Standards Committee (including this commentator), who have been locked into a fight-to-the-death over the field-instrument portion of the standard for almost two years now. While pausing every so often to put out feel-good press releases about working with other standards, weíve been at it hammer-and-tongs, making sure that there are at least three wireless standards for field instrumentation. Actually, there will be six. Six!
WirelessHART devices have already started appearing. At least 14 companies say theyíll have products on the market by first quarter 2009; and they have a strong first-mover advantage, a huge wired HART installed base, interoperability between manufacturers, and end-user familiarity. ISA100 will release a standard later this year or early next year, and at least Honeywell will have products ready instantly. Zigbee has issued an updated version, ZigbeePRO, thatís starting to make inroads, especially in pressure and temperature products. Bluetooth is being used in factory automation for communication between field devices such as proximity sensors, encoders and programming tools. And, for backbone, there are the ubiquitous WiFi (802.11xx) and WiMAX.
Confusing? You bet.
In our cover story, weíve tried to give you some help. One of the things that the ISA100 committee hasnít done, even though that was its official, original purpose and charter, is to provide documentation, benchmarks, best practices and coordination between other standards, so that you know how to install wireless systems. These topics will be taken up by ISA5 and ISA20 in Houston in October for the very first time.
In the final analysis, though, it is you who will have to do more engineering to select the kind of wireless network you want, make sure that bid specifications are written, so that you donít get some of WirelessHART, some of ISA100, some Zigbee and so on when you have a plant constructed. You are going to have to make decisions, and you are going to end up with more than one wireless network in your plant unless you are very careful.
Should you wait?
Thatís a decision in itself. The ISA100 standard will not be an inclusive one. It will be unable to interoperate with WirelessHART and Zigbee, even though it uses the exact same radios. If you were waiting for the ISA standard to make everything right, you might as well stop. It isnít going to happen. Not any time soon.
One of the anonymous respondents to the Control/ISA100 survey just completed said it best. ďISA and my wireless vendor need to specify what plant wireless surveys I must conduct prior to designing my new wireless network. They must tell my how to do it and provide the tools, or they need to do it for me. They need to develop engineering guidelines, so I know how to mount my field instruments and field routers to get a reliable wireless network. ISA needs to develop wireless documentation requirements, such as symbology for P&IDs, network diagrams, ISS sheets, tag naming and others, so I can adequately document my system. When I spec and purchase my instruments, I need to know what factory configuration is required to make sure they will be plug-and-play. I donít want to be forced into site configuration. My vendor needs to tell me how to configure wireless devices in my offline project DCS databaseóincluding use of displays, engineering config, use in logic, etc. And finally, I need to understand what are the appropriate SAT and FAT tests required for wireless devices, if any.Ē
Letís give the man what he wants.
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