Industrial wireless field units: 12 criteria for an effective technology choice

Industrial plants across the world continuously strive to improve their efficiency, enhance the quality of their products, and extend the lifetime of their installations. These 12 criteria will help you choose the best matched wireless technology to boost efficiency, increase resources, and reduce cost.


Image 1: When the XYR5000 line was discontinued, many users thought they had lost access to an easy-to-use star network wireless technology for hazardous areas. Adaptive Wireless Solutions, original creator of the XYR5000 technology, provides direct XYR50Industrial plants across the world continuously strive to improve their efficiency, enhance the quality of their products, and extend the lifetime of their installations. A common requirement for plant engineers optimizing plant performance is the growing need for process and asset condition information. Modern advancement of industrial wireless technology has enabled engineers of any background to easily add or create new measurement points and levels of safety in their industry at lower cost. 

Mesh architecture and star network transmitters

Data communicated from field units is transmitted to a base radio, which acts as a gateway to the control system over a star network central hub. Star network wireless field units monitor gauge, absolute, and differential pressure measurements, as well as temperature and acoustic monitoring (commonly used to sense ultrasonic noise for gas and steam leak prevention). This topology allows for simple architecture and a very easy installation and startup over the 902-928 MHz frequency band. Efficient use of the wireless power can cover distances between 2,000 and 3,000 ft (line of sight) without repeaters, as designed for large area industrial plants.

Another wireless technology utilizing an ad-hoc "mesh" architecture has become an alternative to star network transmitters. The mesh network relies on field nodes that self-organize to create a route (or multiple routes) for process information transmitted to a control room. With an operating frequency of 2.4 GHz, the reliability and self-healing ability of this network grows with its number of devices; however, so does complexity. The maximum distance the network can cover also depends on the location and number of nodes. In the specific case of WirelessHART, a minimum number of at least five devices is required to obtain the benefits of intrinsic redundancy and the network's ability to self-organize. This requirement may prompt users to add repeaters in their system or externally powered devices, which contradicts the benefit of using wireless devices.

With more choices, instrumentation engineers now face a significant challenge to select the best wireless technology for their plant. Although the technologies are well differentiated, it is not always easy to select one wireless architecture over another without a specific set of criteria.

Criteria for choosing technology

The "needs vs. benefits" analysis that leads to the use of wireless transmitters typically considers:

  1. The addition of new measurement points at low cost, without using wires, and
  2. The ease of installation and commissioning.

Simple star network architecture satisfies even the most basic applications. But in reality, the number of industrial wireless applications grows every day as users continue to discover the advantages and uses of the technology. A deeper analysis of these applications will demonstrate in most cases that star network wireless technology is highly suitable for most users' needs for a lower cost and effortless preliminary configuration. However, other factors may influence the decision in a different direction. The table below provides a list of criteria to be used for the selection of the most suitable wireless architecture depending on the application, the user's technical capabilities, and the budget.

Chart: Chart comparing Star Network, ISA100, and WirelessHART based on 12 criteria. Courtesy: Hector Barresi

*Battery life is directly related to duty cycle, power and efficiency of the radio, battery type and size, existence or not of some energy harvesting device, and more. Above numbers vary greatly, but in general, star topologies tend to be more efficient as the field devices do not have to re-transmit signals from other devices, which is the case in mesh networks.

** The distance covered by the wireless transmitters varies largely depending on a number of factors, such as the topology of the plant, obstacles, repeaters, and type and location of the antennas. In the particular case of WirelessHART and ISA.100, the determination of the maximum distances covered by the devices in the mesh network is even more complex, and different manufacturers provide different figures as well as empiric results from measurements taken across industrial plants.

The industrial spectrum consists of countless requirements and conformity standards. Installing the best matched wireless technology in your facility boosts efficiency, increase resources, and reduces cost.


  • WirelessHART vs. ISA100a, Stig Peterson and Simon Carlsen
  • Field Wireless — Test Report Nbr. 7 — ISA100. 11a, Yokogawa Electric Corporation
  • OneWireless Network Overview — Product Information Note, Honeywell Process Solutions
  • Broadcast Range of WirelessHART Transmitters
  • Emerson Process Experts, Emerson

- Edited by Anisa Samarxhiu, digital project manager, CFE Media, 

Key Concepts:

  • With more choices, instrumentation engineers now face a significant challenge to select the best wireless technology for their plant.
  • Installing the best matched wireless technology in your facility boosts efficiency, increase resources, and reduces cost.

Consider this

How do you select the most suitable wireless architecture?

ONLINE extra

Learn more about the XYR5000 and related articles about industrial wireless networks below.

Jonas , Singapore, 05/23/15 05:29 AM:

I agree that wireless transmitters are excellent for applications such as improving reliability, energy efficiency, reducing HS&E incidents and response time, and improving productivity etc.

I personally believe the first criteria (which was missed out) is that the wireless technology shall be an industrial standard such as IEC 62591 (WirelessHART). Most plants have experienced the pain associated with being locked in with proprietary protocols for their wired transmitters and electric actuators / motor operated valves (MOV), tank gauging systems, and gas chromatographs etc. back in the 1990’s. Plants need not get into that situation again. Make sure to invest in standard wireless infrastructure supported by multiple vendors. WirelessHART is supported by more than a dozen manufacturers.

Drawbacks of proprietary technologies include lock-in to a single vendor, so once the proprietary infrastructure has been deployed, any expansions or replacement required in the infrastructure is now single source so cost might go up. Same goes for the transmitters which also must come from the same single vendor. The single vendor may not have all the type of sensors required to meet all the application demands by all departments in the plant (reliability/maintenance, energy efficiency & loss control, HS&E, mechanical, and operations etc.). Deploying multiple diverse wireless networks to satisfy all application needs becomes a lot more challenging to manage. By using a standard like IEC 62591, users can buy wireless network infrastructure from one vendor, extend it or get replacements from another vendor. Transmitters are also available from multiple vendors, so users can choose from a much broader spectrum of sensors including vibration, valve position, radar level, pH, conductivity, vibration fork level switches, corrosion, and many other things.

Line of sight (LoS) does not exist in most plants because most plants are full of metal; steel vessels, pipe racks, and structural steel which cannot be penetrated by radio signals. When you stand in the middle of the plant unit and look in any direction you cannot see very far; 30-50 m (100-150 ft) at best. For this reason star topology does not work very well inside plants. Star network solutions have existed for decades but never became mainstream inside plants because of the challenges posed by all the surrounding steel. Only when full mesh topology was introduced with WirelessHART a few years ago could the challenges of these canyons of steel be overcome, and as a result of full mesh topology the adoption of wireless sensors in plants is now very fast.

That is, it doesn’t matter if the line of sight distance of the radio is 250, 600, or 1,000 m (800, 2,000, or 3,000 ft) because inside the plant you or the radio signal can never see that far because of all the obstructions. What matters inside the plant full of steel is the ability of the PV transmission to work its way around obstacles. This is where mesh topology comes into play. When the line of sight from one transmitter to the gateway is blocked, the signal from that transmitter can instead ‘hop’ to another neighboring transmitter which in turn retransmits the signal to the gateway directly or alternatively through several other transmitters until the signal reaches the gateway. Sounds complicated? Well, for the user it isn’t, because the routing of the signal happens automatically. It is self-organizing. This also means that if the environment changes (new obstructions like a tanker truck or whatever is introduced), the signal route will automatically be changed to ensure the signal reaches the gateway. Only in cases where there aren’t any transmitters to route through does a repeater have to be deployed. The repeater is also battery powered so it is very easy to deploy. This compares favorably against star topology. In a star topology, if the signal from a transmitter to a base station is blocked by some obstruction, you will simply have to deploy another additional base station which is line of sight from the device. This makes star topology more difficult to use for the user even though the technology is simpler.

WirelessHART works in plants where other wireless technologies have been tried and failed

With 100 devices per WirelessHART network you can achieve 8 second update period. With fewer devices you can go as fast as 1 second.

WirelessHART repeaters do not require external power

The level of expertise required is low because a WirelessHART device can be commissioned using the same handheld field communicator as the plant already have and use for their 4-20 mA and fieldbus devices. They also use the same tool for other configuration, calibration, and diagnostics etc. and it is done the same basic way.

Battery for WirelessHART devices can last up to 10 years.

A meshed networked device can achieve the same distance as a star topology device, or longer if other devices are present or repeaters added

If the plant has deployed Intelligent Device Management (IDM) software part of their Asset Management System (AMS), WirelessHART devices can be integrated with such software which compares favorably against proprietary technologies which requires dedicated software to manage the devices. Learn more about IDM (device configuration, diagnostics, and calibration) here:
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