Five years ago some of the brightest minds in the automation industry began working on a revision to the HART 6 standard that would include the ability to construct wireless sensor networks on the HART protocol platform. Unfortunately, some of those same bright minds also to begin work on an ISA wireless standard that was envisioned at the very beginning to be completely incompatible with HART. The result was acrimony, and we got us a wireless standards war—just like we had with fieldbus, and just like the FDT/EDDL conflict we are hopefully close to resolving with the Field Device Initiative (FDI). End users really hate standards wars.
Siemens has become the latest major field-device vendor to release products certified for WirelessHART. Most of the major field-device vendors now have products that are either in the certification process or in the final release to shipping. All the major field-device vendors are scheduled to ship some WirelessHART-certified products by the end of this year.
To top it all off, the IEC has approved WirelessHART as IEC 62591Ed. 1.0, the first global standard for wireless sensor networks.
ISA100.11a, although approved by ISA last October, has not been approved by ANSI as an American National Standard. ANSI made some suggestions. Clearly, since the ISA standard is already far behind, this wasn't ISA's first choice.
Shell did a test of a use case that was presented at the ISA100.11a meeting in February, which indicated that some serious problems existed with the ISA100.11a standard. This simple use case, two temperature transmitters and a gateway basically did not work. Other use cases might, but this one did not.
Rather than continue the argument with ANSI, the ISA100 committee is working on a "maintenance activity" to clean up the technical issues and handle the procedural violations that have kept the standard from being approved by anybody but ISA. The plan is to have a revised standard available for approval in October by ISA and sent to ANSI thereafter.
Meanwhile, the end user community has gotten so fed up with the wireless standard war that it spoke out vigorously at the ARC Forum/ISA100 meeting in February on behalf of a single wireless standard.
Everybody once believed that ISA100 would be that standard. Now however, it is becoming difficult to see where a revised ISA100.11 standard fits.
If vendor politics would permit, the sensible thing would be to declare WirelessHART the field device standard, and continue with the less contentious Backhaul, Power Harvesting, Discrete Manufacturing and other committees of ISA100.
My belief is that the success of wireless sensor networks depends a great deal on how easy it is to select and install them. Multiple sensor network standards clearly disrupt and damage the market, and as the fieldbus standards war has shown, seriously slow the adoption rate of new technologies.
There are things I wish WirelessHART would do that ISA100 was supposed to do, and probably will, when the "maintenance activity" is completed. But that is going to take another six months to a year before working products are released. By that time, there will be thousands of WirelessHART devices installed and working in end-user plants.
Given that the lifecycle of field devices is between 10 and 20 years on average, who's going to rip out WirelessHART devices to replace them with incompatible ISA100.11a devices? Somehow I don't see that happening, do you?
So, my fellow ISA100 committee members, let's think about the possibility of doing something for the end users, shall we?
