Commercial wireless networks have their place, but a different type of wireless network is needed for industrial applications.
Bob Karschnia, VP of Wireless at Emerson Automation Solutions, writes in his article, Wireless Infrastructure for Industrial Applications in IT Infra World magazine, that “The IIoT in process plants requires very reliable and consistent connectivity from hundreds or even thousands of sensors to host systems. The sensors measure plant operating parameters including temperature, pressure, level, flow, vibration and many others.”
This measurement data is sent via a wireless network to a host system where it’s used to help plants increase uptime and throughput, reduce energy use, improve safety and make other operational improvements.
Unlike commercial networks, industrial wireless networks have to deal with multiple obstructions in the form of equipment, metal buildings, trucks, etc. They also have to cover very large areas, up to a few square miles for mining operations or big chemical plants, operate for years without any maintenance, and deliver data at consistent update rates regardless of network loading.
“Decades of research and real-world application experience have shown the best way to meet these challenges is with a self-organizing and self-healing mesh network, such as WirelessHART®", Bob explains.
“Another big difference between industrial and commercial wireless networks is required uptime. The ability to run for years without maintenance is critical for industrial facilities as many operate 24/7/365, with maintenance shutdowns typically scheduled years apart,” he notes. “This requirement is made even more difficult by the harsh environments often found in industrial plants where wide temperature swings, heavy vibration, corrosive atmospheres and other adverse conditions are common.”
Update or communication rates are another area where industrial and commercial wireless networks differ. The communication rates of most commercial wireless networks slow significantly as more users join the network, and as users load the network with more traffic. This can slow the network to the point where use is impractical.
Bob explains that industrial wireless networks require stable update rates, defined as how often a sensor transmits data to a gateway. “Typical update rates for sensors range from one to five seconds, and the update rate at each sensor can be set individually. Once set, the update rate will be stable regardless of network loading.”
Once a WirelessHART or other industrial mesh network is installed, plants and facilities can begin to realize the operational benefits of the IIoT. Adding new sensors is quick, easy and inexpensive—so plants can quickly expand their IIoT installations to meet new operational challenges.