Sensors powered by ambient vibration, thermal gradient or RF energy at the measurement point, eliminating battery replacement as a maintenance task entirely.
WirelessHART / ISA100.11a mesh instrumentation
Self-organising 2.4 GHz mesh networks for process instruments, standardised since 2010 and now a routine engineering choice for monitoring points where running a cable would cost more than the measurement is worth.
How the network works
WirelessHART adds a radio to the HART protocol that most process instruments already speak. Devices use IEEE 802.15.4 radios in the 2.4 GHz band, transmit in scheduled time slots and hop between channels from one slot to the next, so interference on any single channel affects only a share of transmissions. Every device can route messages for its neighbours, which gives each instrument more than one path to the gateway. A network manager, usually inside the gateway, builds and maintains the schedule and the routes.
Security is part of the standard rather than an add-on: traffic is encrypted and authenticated with AES-128, and a device can join only with a key provisioned during commissioning. The gateway connects the network to the host system through Modbus, HART-IP, OPC or vendor-specific interfaces.
WirelessHART was approved as an IEC standard, IEC 62591, in March 2010, a few months after NAMUR reported that it met its requirements following a multi-vendor field test at BASF in Ludwigshafen 1. The current edition is IEC 62591:2016 3. Its rival, ISA100.11a, uses the same IEEE 802.15.4 radio with a different protocol stack 2; it was later published as IEC 62734 and remains in use at sites that standardised on it. A device of one standard cannot join a network of the other.
What it is good at
The economics are simple. A wired measurement point in a process plant carries the cost of cable, tray, junction boxes, marshalling, I/O and hazardous-area documentation, and the instrument is often the cheapest part. A wireless transmitter replaces most of that with a battery. The typical uses are points that would otherwise never have been instrumented: tank and pipeline temperatures, local pressure gauges converted to transmitters, steam traps and relief valves, vibration on rotating equipment and corrosion probes.
Reporting rates are configurable, typically from a few seconds to several minutes, and battery life depends heavily on that choice. At update rates of a minute or slower, multi-year battery life is realistic; at a few seconds it shortens considerably. That trade-off is the main design decision on most projects, and it is worth making point by point rather than with one default for the whole network.
Where it is the wrong tool
WirelessHART is a monitoring technology first. It can carry control signals, and some users close slow loops over it, but the reporting interval, the latency and the consequences of a missed update rule it out for fast or critical control and for safety functions. It also has little bandwidth to spare: it carries measurements and diagnostics, not waveforms or video.
A mesh needs neighbours. A handful of devices spread over a large site, or a single device behind a wall of steel, will struggle. FieldComm Group's deployment guidelines cover planning, network design, commissioning and acceptance criteria 4. Following the design rules on device density and gateway placement is the most reliable defence against poor network performance.
Living with it
- Battery replacement is the recurring cost. Plan it as a maintenance route and use the devices' battery diagnostics rather than a fixed calendar.
- The gateway is the critical component. Use redundant gateways where the data matters, and treat the gateway as a networked OT asset in the site's security design.
- Watch the spectrum. Wi-Fi and WirelessHART share the 2.4 GHz band and coexist in practice, but large new 2.4 GHz deployments should be checked against existing instrument networks.
- Decide early how wireless points appear in the control system: as normal tags under the same alarm philosophy, or as a separate monitoring layer.
Evidence timeline
- Nov 2009NAMUR reports that WirelessHART meets its requirements after a multi-vendor field test at BASF Ludwigshafen. 1
- Mar 2010IEC approves WirelessHART as international standard IEC 62591. 1
- 2016Second edition, IEC 62591:2016, published. 3
Why it sits at the Proven in Use stage
This is the most mature entry on the curve: an international standard for more than fifteen years, multiple suppliers of devices and gateways, published deployment guidelines and a long field record. The technology itself is changing little. Growth now comes from new uses, such as condition monitoring programmes, rather than technical change.
We have not found a reliable, recent public figure for the worldwide installed base, and supplier claims vary. The placement therefore rests on the length of the deployment record and the breadth of supplier support, not on a device count.
Adoption signals to watch
- Whether new monitoring points go to WirelessHART or to alternatives such as Ethernet-APL, private cellular or low-power wide-area sensors.
- Energy-harvesting power options that remove battery replacement for suitable points.
- Gateways certified against IEC 62443-4-2 component security requirements.
Questions to ask before committing
- How many devices will each gateway serve, and does every device have enough neighbours for a reliable mesh?
- What reporting rate does each point really need, and what battery life does that give?
- Is gateway redundancy needed, and how does the gateway connect to the host system?
- Who replaces batteries, and where do low-battery diagnostics go?
- If the site already uses ISA100, is a second wireless standard justified?
Terms used on this page
- Mesh
- A network in which devices relay each other's messages, giving several routes to the gateway.
- Channel hopping
- Changing radio frequency from slot to slot to ride through interference.
- Gateway
- The device that connects the wireless network to the host control or monitoring system.
Sources
- Status update: ISA100 & WirelessHART
- WirelessHART vs. ISA100.11a: what's the difference?
- IEC 62591:2016 Industrial networks – Wireless communication network and communication profiles – WirelessHART
- FieldComm Group to host webinar detailing WirelessHART deployment guidelines
Related technologies
See this entry on the full maturity map · All Instrumentation entries · How placements are made. Stage and time-horizon placements are editorial judgements based on the public sources listed above, as of October 2026. They are not engineering, safety or investment advice; see the Terms of Use.