Wireless Technology as a Work in Progress
Strategy and tactics: Process industry users, vendors discuss obstacles to implementation, appropriate applications, and standards for plant-level wireless.
ONLINE extra Read other articles in the Wireless Communications for Industry , a supplement to the November 2009 Control Engineering print edition, which contains:-Wireless Enables Huntsman Project Zero-Wireless Technology as a Work in Progress-Plant Deployment Demonstrates Wireless Standard-Transparent Wireless at Cano Petroleum Also see :- Application close-up: Wireless devices support equipment monitoring ; – Wireless networks: Adding cellular technology to the industrial toolbox ;- How to stretch wireless I/O throughout manufacturing ; and- Wireless I/O, module IWLAN, saves time, money .
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What’s holding back broader adoption of wireless technologies in the process industries? A panel of vendor and user experts discussed that and other topics at October’s ISA Expo in Houston. It seems that although technical and attitudinal obstacles to this emerging technology remain, many are being systematically addressed and overcome. Panel members included Peter Fuhr, Wi-Fi Sensors Inc.; Patrick Schweitzer, Exxon Mobil and ISA 100 committee co-chair; Jose Gutierrez, Emerson; Herman Storey, recently retired from Shell Global Solutions; Dave Kaufman, Honeywell; and Ed Ladd, HART Communication Foundation.
One obstacle suggested by panelists was a sense of risk related to communication failures (“Can you hear me now?”). Some users aren’t convinced that the signal will get through when it has to. Another thought was that the discussion has largely moved from technical and reliability issues to disagreements over system ownership, meaning that, from the perspective of plant managers, IT groups tend to latch onto wireless more than other plant level technologies, and then want to exercise control or at least have influence over deployments. IT people know what wireless is, as opposed to something like a fieldbus, and they’re concerned that unmanaged experiments in the plant could interfere with their systems.
While security is still an important concern, the consensus among current and potential users was that technical solutions are possible and are already being implemented. While wireless Ethernet (Wi-Fi) may present an attack surface that hackers understand, instrumentation-level communication would be difficult to penetrate, although users should not rule out that possibility. There were questions about use of wireless technology with safety systems and specific safety devices, such as gas detectors. The panel recoiled somewhat at the thought of using wireless with ESD (emergency shut down) related equipment, but was willing to consider things like gas detectors. Herman Storey made a critical point about safety equipment: You have to ask yourself how you would know if it stops working. If a device isn’t supposed to do anything until there is a problem, you have to be able to verify that it is actually functioning all the time, so it can do its job when there is an emergency.
Users also are concerned about multiple systems interfering with each other, since there is a limited amount of air space. The group did caution against unmanaged deployments of multiple systems in a plant environment, since these can cause problems if not well thought out. There have been cases of deployment interference in discrete manufacturing facilities, but those usually involve older equipment that uses higher-power radios and less effective bandwidth use. Carefully planned systems can support a huge amount of equipment if applied well, particularly given the efficiency of current wireless process instrumentation.
Wireless standards were the most contentious area discussed. The group was roughly split between those favoring WirelessHART and those favoring ISA-100.11a for process field devices. There were parallels drawn to IEC-61158, which has reduced its value as a standard by allowing a whole group of incompatible fieldbus technologies to exist in parallel. Users wanted to know if vendors would offer multiple platforms, in the same way that many devices are available with multiple wired communication protocols.
The responses from the two vendors represented were unequivocal: Emerson says it will only use WirelessHART, and Honeywell says it will stay with 11a. (As a historical sidenote, while there have been suggestions that WirelessHART and ISA 100.11a were, for all practical purposes, designed by Emerson and Honeywell respectively, neither standard reflects the corresponding predecessor in any but the most general ways, and neither of the companies’ earlier proprietary systems is compatible with the standards as approved.) Less aligned individuals suggested that market realities will prevail in time, and that other vendors may not be so doctrinaire. Companies may not want to offer both, but the technologies are similar enough that it certainly is possible. Within the ISA100 committees, there is a group to create a convergence of the two competitors, and hopefully this will bear fruit. However, in the near term, companies will have to make choices — it will not be practical for an end-user to try them all.
Patrick Schweitzer, for example, says that Exxon Mobil has already selected 11a for field instrumentation even though it has been ratified for only a month. It will be interesting to see how the influence of a major user will steer ongoing developments. The ISA 100.11a Wireless Compliance Institute also operates in a wireless instrumentation network following the standard at the Arkema organic peroxide plant in Crosby, TX. (See related article in this supplement.)
One moment in the discussion put things in perspective when Herman Storey observed that users have to approach the whole question with the larger picture in mind. Having something like mobile operators is strategic. Adding one more pressure or temperature reading is tactical. Few technologies have provided so many possibilities to implement plant improvements, from a single process variable to walk-around HMIs. Users need to be more creative and consider what wireless can accomplish in the broader sense, rather than simply doing the same things without wires.
Peter Welander is process industries editor. Reach him at PWelander@cfemedia.com .