Wireless warning

Industrial wireless technology is now moving from pilot and niche project status to full-scale working installations. Finally, the future is bright for plants and factories wanting to ramp up efficiency, increase productivity and improve safety by wirelessly connecting those processes and machines where hitherto hard wiring was either infeasible or too dangerous. Or is it? According to GAMBICA – the trade association for instrumentation, control, automation and laboratory technology – this important progress may be heading for a train crash. Why? Incredibly, an international standards body focused primarily on consumer and commercial activities has come up with a new standard for maximising the 2.4GHz ISM band – which covers millions of devices using WiFi and Bluetooth, but also WirelessHART (IEC 62591), ISA100.11a and Zigbee. However, it's one that may render industrial wireless unworkable. Andrew Evans, technical executive at GAMBICA, is warning of an "imminent major industrial wireless failure". He also believes that the UK could lose some technology leadership – certainly in terms of industrial application – in a market expected to grow 18% annually, with some three million wirelessly-enabled industrial products forecast for shipment next year (IMS Research). How has this come about? Evans explains that in a bid to preserve bandwidth, ETSI (the European Telecommunications Standard Institute) has written a harmonised standard, EN 300 328 v.1.8.1. So far, so good: its move is in line with the R&TTE (Radio and Telecommunications Terminal Equipment) directive – which states that 'radio equipment shall be so constructed that it effectively uses the spectrum allocated to terrestrial/space radio communication and orbital resources so as to avoid harmful interference'. However, its standard, which amends existing rules for all devices using the public radio band, appears to cause problems for industrial wireless control systems. And it comes into force on 1 January 2015. "The problem with the EN 300 328 standard is that it introduces the concept of LBT [listen before talk]," states Evans. "LBT requires each radio device to first check whether another is transmitting, in which case it must hold back until the channel is free. But this causes random and unpredictable communication delays." Time of the essence And hence the problem for time-sensitive plant monitoring and control. "The entire idea is simply non-viable: at times of heavy use, the result is supposedly 'graceful degradation of service'. Unfortunately, if this happens, key wireless devices on industrial devices [will] never be relied upon to report their alarm or status messages in a timely fashion," insists Evans. Industry, he continues, has tried working with ETSI by submitting comments for revisions of EN 300 328 – including suggesting exemptions or optional uses of LBT within defined industrial automation areas. However, these have not been included in ETSI's latest revision of EN 300 328, at v.1.8.1. Further, industrial representatives to IEC (the International Electrotechnical Commission) technical committee SC65C – which is usually responsible for global standards around industrial data communications subsystems and instrumentation – have developed IEC 62657-2 (2013) 'Industrial Communication Networks – Wireless Communication Networks – Pt 2: Coexistence Management'. That compromise standard does what it says on the tin – effectively allowing ETSI's EN 300 328 standard and existing industrial wireless standards to coexist. But, although voted positively by CENELEC (the European Committee for Electrotechnical Standardisation), harmonisation of this standard has been blocked by ETSI. "This stance is likely to make Europe lose significant competitive ground in industrial wireless," warns a clearly frustrated Evans. If a technical and/or political compromise cannot be reached, it also puts at risk all the hard work by equipment developers and manufacturers, as well as process plant managers, engineers and technicians who have been proving that wireless fieldbus communications not only work, but can significantly improve plant productivity and safety, while also cutting costs. All may not be lost, however, according to Ted Schnaare, director of engineering for WirelessHART pioneer Rosemount Wireless (part of Emerson Process Management). "While this continuing [standardisation] effort is underway, we have carefully reviewed the provisions of EN 300 328 v.1.8.1 and have tested our products in accordance with the new requirements... Based on this evaluation, we are confident that our existing products comply and will continue to function reliably after the new standard comes into force," he says. "The new standard does allow equipment that implements LBT to transmit at higher power levels. We are naturally interested in participating in standards efforts that allow maximum transmit power, preserve coexistence and recognise the real-time requirements of industrial wireless systems," he adds diplomatically. Either way, GAMBICA is urging firms providing industrial wireless equipment, or whose services rely on these systems, to contact their UK trade associations or opposite numbers on the continent. "Industry needs to make further efforts to explain the possible consequences of LBT to the European Commission and call for the harmonisation of IEC 62657-2 under the R&TTE directive as soon as possible," insists Evans. "BSI [the British Standards institute] needs to be encouraged to follow their charter by representing the needs of UK industry," he continues. "And BIS [the government's Business, Innovation and Skills department] should also be able to help change ETSI's position." Wireless wonder transmitter Wireless process control technology is still in its infancy, but widely seen as a huge potential growth and improvement area. Indeed, just recently the legendary ultra-precise Rosemount 3051S multi-variable process transmitter was relaunched in wireless format for that very reason. At the launch, developer Emerson made the point that plant engineers could use the device to gain greater process knowledge by monitoring two process pressure variables (differential and static – true gauge or absolute) while slashing installation costs and timeframes. On the one hand, that was because of the two-for-one aspect: one transmitter for two measurements – meaning fewer pipe penetrations and impulse piping. On the other, it was absolutely due to wireless technology – meaning no trenches, ducts, physical I/O connections and the rest. This device, like many others, works with WirelessHART (IEC 62591) digital communications, with Emerson stating that plant users can expect a decade of maintenance-free performance and a 10-year transmitter stability specification. If ETSI's EN 300 328 v.1.8.1 holds sway, then that promise may not be so easy to keep.