Industrial wireless devices and networks are used for measurement and control applications in areas of process plants where it is too difficult or too expensive to hardwire sensors, transmitters, and final control elements. They are also used for temporary applications, such as in research and development and pilot plants. Although most consumer wireless networks are used for convenience, industrial field wireless networks must be much more reliable, and cannot interfere with other wireless applications in the plant. These networks, and their accompanying wireless devices, must also be simple for existing plant personnel to support. Finally, industrial wireless networks and devices must easily integrate with existing wired devices and networks, and the entire wireless system must be flexible and scalable.
Wireless solutions for the process industry
There are three basic areas in which industrial field wireless networks can operate in the process industry: the global canopy, a site backbone, and a field mesh. The global canopy is the term used for long-range wireless communication. It can be made up of a site-to-site private network joining locations up to hundreds of miles apart, or it can use public networks, such as the Internet, a satellite, or cellular communications. This type of network is used for data transmission over very long distances.
A site backbone is a good solution in cases where data is transmitted from cell-to-cell within a transmission distance of a few miles. Although the distances covered are shorter than with a global canopy, a site backbone network can still be used to transmit data over relatively long distances.
A field mesh or wireless sensor network is used for sending and receiving a few kilobytes (kB) of data over a short range up to a few hundred feet. These field wireless networks are comprised of sensors and actuators, field mobile devices, and field end points—and these types of networks will be the focal point of this article.