INDUSTRY 4.0/IOT/AI
BRIDGING THE INDUSTRY 4.0 DIVIDE
Why WirelessHART remains the pragmatic choice for harsh process environments, by Liam O’Donnell, Senior Software Engineer, ByteSnap Design & Dan Lees, Hardware Engineer, ByteSnap Design
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n heavy processing plants, chemical facilities and offshore platforms, generic wireless deployments have a habit of falling apart. Dropped packets, batteries dying months ahead of schedule, signals degrading the moment they encounter dense steel infrastructure, competing RF traffic, and electromagnetic chaos all can occur in heavy industry. Standard commercial wireless protocols were designed for offices, warehouses, and consumer devices, not environments where a failed reading can mean a missed alarm, and a missed alarm can mean something far worse. Expecting them to perform reliably in a refinery or a chemical plant is a bit like specifying outdoor furniture for an Arctic drilling platform. Technically, it’s still furniture, but it was never really built for the job. Closing the gap between digital ambition and operational reality means rethinking the foundations. Engineering teams that have done this successfully have stopped treating connectivity as an afterthought and treat it as a discipline in its own right. For process instrumentation in hazardous areas, that discipline has a well- established standard at its centre: WirelessHART.
Challenges for wireless signals When deploying wireless instrumentation in a process plant, designers face severe radio frequency (RF) propagation challenges. Heavy industrial environments, dense matrices of structural steel, concrete, and high-voltage machinery, present three distinct challenges for wireless signals: • Radio signals reflect off steel structures, creating multiple transmission paths that arrive at the receiver out of phase, effectively cancelling each other out.
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• High-power pumps, switchgear, and variable speed drives generate localised electromagnetic noise that can cause interference and “blind” standard wireless receivers.
• Physical changes, like a crane moving into a sightline or the installation of temporary scaffolding, can create obstructions that, however temporary instantly sever static point-to-point wireless links. WirelessHART addresses these challenges
through its architecture, thanks to operating on the 2.4 GHz ISM band, using time-synchronised channel hopping (TSCH) alongside a self-healing mesh topology. Because every node can act as a router, the network automatically redirects data through alternative paths if a localised obstruction occurs.
Overcoming the intrinsic safety power dilemma For hardware developers working with industrial device manufacturers, designing a WirelessHART instrument introduces a complex design constraint, the “intrinsic safety power trilemma”. Engineers must balance three competing requirements simultaneously. They are high RF performance, an operational battery lifespan that can reach 10 to 13 years at conservative update rates, and strict adherence to ATEX/IECEx Intrinsic Safety (Ex ia/ib) standards.
Under Intrinsic Safety regulations, the total energy stored in the circuitry of a device must be limited to prevent any possibility of a spark igniting an explosive atmosphere. Because energy storage is governed by the equation E = ½CV², adding large bulk capacitors to handle the high current surges required during wireless transmission is not always allowed. Instead, design teams must apply
PROCESS & CONTROL ENGINEERING | JULY/AUGUST 2026 “ Industrial
wireless instruments have to keep working in conditions that would kill a consumer device within weeks
strict design constraints to device hardware and firmware techniques.
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A common technique is to reduce voltage rails in line with the IEC 60079-11 permitted capacitance (table A.2). For Group IIC apparatus, halving the rail from 12V to 6V increases the permitted capacitance from 1.41µF to 40µF, a factor of around 28. Dropping further to 4V increases the allowance to around 600µF. As voltage rails in the 3.3V to 5V range are common in modern low-power MCUs, there is significant design headroom for the energy reservoir RF transmission bursts required. Where design constraints stop it being possible
to reduce the rail voltage, a protection concept of encapsulation is used. This method permits the stored energy limits, set out by IEC 60079-11, to be exceeded. As long as it can be shown that it is not possible for the explosive gas to be exposed to the energy under fault conditions.
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