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.
Industrial 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:
- The addition of new measurement points at low cost, without using wires, and
- 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.
*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, firstname.lastname@example.org
- 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.
How do you select the most suitable wireless architecture?
Learn more about the XYR5000 and related articles about industrial wireless networks below.