Unplugged: Developing Standards for Wireless Automation

ISA 100.11a and WirelessHART both seek to become the global standard for industrial wireless automation.
May 02, 2008
Volume 32, Issue 5

The great disadvantages of new technology are that its commercialization involves a high degree of risk and its future holds an even higher level of unpredictability. Wireless industrial automation has been slowly embraced by some petrochemical and chemical processing companies. Meanwhile, the highly conservative pharmaceutical industry has so far, and not surprisingly, taken a wait-and-see position—and for good reason.

Which wireless?
To build the most robust and secure wireless devices, suppliers build according to an approved standard. Wireless Internet communications, for example, all comply to the familiar IEEE 802.11 (b, g, and n) standards. Currently, both the HART Communication Foundation (HCF, Austin, TX) and ISA (Research Triangle Park, NC) are involved in putting forth an industrial wireless standard at the basic "bits and bytes" level (i.e., sensors) (see sidebar, "Which wireless?"). HCF released its standard, WirelessHART (HART generation 7), in September 2007. To date, ISA is continuing to develop a draft of its standard, officially noted as ISA 100.11a (often referred to as SP 100).

Both organizations aim for global acceptance, including by the pharmaceutical industry, which thanks to the move toward quality by design, is preparing for increased in-process monitoring. Both HCF and ISA agree that a wireless standard is the right step to advance process automation and communication. Both are aware they are competing to achieve the same objective. And of course both would argue that their standard is the most beneficial, robust, and secure.

Brief history

Dual standards are not new to process automation. For example, the original wired HART digital standard was developed more than 15 years ago to be carried on top of the existing 4-20 mA analog signal. At that time, HART was an emerging communications protocol. "If you look back 10 years, HART wasn't supposed to be where it is now. I recently looked at the articles that were written and they said HART was an interim technology and by 2005 it was supposed to be dead or dying from a technology standpoint," says Ed T. Ladd, Jr., director of technology programs at HCF. HART is now worldwide and is the most used protocol for field devices in the process industries. HCF built upon that technology when developing its WirelessHART standard, which was reviewed and approved by its membership and ratified by its board for release on Sept. 7, 2007.

Figure 1: Prestandard wireless transmitters are now in use, and Emerson Process Managment has announced the availability of SmartWirelessHART transmitters. (PHOTO COURTESY OF EMERSON PROCESS MANAGEMENT)
Emerson Process Management is currently the only company that has announced the availability of WirelessHART devices (see Figure 1). Although none have been installed at this time, prestandard wireless devices continue to be in use. "To date, we know that member companies are actively developing WirelessHART products to be offered for sale by the end of the calendar year," says Ladd. "Major vendors, including ABB, Emerson, Endress +Hauser, and Siemens, have all committed to support the technology."

At the time WirelessHART was released, ISA had been working on ISA 100.11a. "ISA began to work on a wireless standard in 2004. I'm not sure what the motivation was on the part of the people who decided they would not wait for ISA 100 but would build on available technology and develop WirelessHART," says Richard Caro, certified automation professional, CEO of CMC Associates, and chair of a user-working group for ISA. "ISA 100.11a is beginning to develop rather quickly and at this point is almost complete. The standard is scheduled for voting and approval by the end of 2008."

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