ISA100.11a rejected at IEC #pauto #wireless #automation @ISA

Feb. 14, 2013

Welcome to another edition of the wireless standards polka. You know, the dance that keeps confusing end users to the point that they don't want to use any wireless devices except 802.11 WiFi.

Welcome to another edition of the wireless standards polka. You know, the dance that keeps confusing end users to the point that they don't want to use any wireless devices except 802.11 WiFi.

Despite extensive rewrite by IEC wireless expert, and Process Automation Hall of Fame member, Tom Phinney, the IEC ballot closed last month without enough yes votes to proceed with ISA100.11a as an IEC standard. There were more yes votes than no votes and abstentions, but the ballot failed to achieve the two-thirds majority necessary to pass the proposal. At the IEC, the voting is done by country, and more than10 countries submitted comments, mostly technical.

These technical comments must be resolved by the TC65 committee and ISA before the ISA100.11a standard can be re-submitted to IEC.

So, then, what does this all mean?

From an end-user or asset owner or integrator's perspective, it means another year of uncertainty over which standard to choose. There are four standards that are being used for field devices: IEC62591-WirelessHART, Zigbee, Wia-PA (the Chinese national standard) and ISA100.11a.

Zigbee has, despite serious flaws, flaws that led directly to both HART 7 and the WirelessHART extension, and to ISA100, been named by governmental fiat the wireless protocol of "smart grid." This has resurrected a standard that in the industrial world was nearly dormant. Several valve and device companies and at least one SCADA vendor have decided to adopt Zigbee as their wireless field device standard instead of either IEC62591-WirelessHART or ISA100.11a.

Yokogawa, the third largest manufacturer of field devices, has led the movement for ISA100.11a, along with Honeywell and a GE division. The rest of GE and almost all the other field device (instruments and control elements) vendors have lined up with IEC62591-WirelessHART.

What should have happened years ago is that ISA should have written at the most a wireless transport protocol that would allow people to wirelessly transmit the digital fieldbus protocols, HART, Profibus, Foundation fieldbus, that they were already using, instead of creating an entirely new wireless fieldbus protocol. 

ISA could still do this, as the ISA100.12 committee report showed. Oh yes, you can't read that report, can you? That's because the ISA100.11a supporters voted to keep the report in committee and not release it. And then they voted to kill the convergence effort entirely.

So what's a poor end-user to do? Don't wait for this pointless dance to finish, because it may never do so. If you think there is benefit to having wireless field instruments, go with the standard that your preferred supplier is supporting. If you have a supplier that supports one, and another supplier that supports the other, you may have to choose between suppliers.

This may get easier, now that Yokogawa has joined the HART Communication Foundation board. Perhaps this signals a willingness to provide whichever standard the end users prefer. So if you already have IEC62591-WirelessHART devices, and millions of dollars worth of them have been sold, you may be able to get the erstwhile ISA100 vendors to give you WirelessHART.

As Ian Verhappen is showing in his Without Wires column every month in Control magazine and on, there is plenty of room for wireless in your control and asset management strategy. 

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