Are you broadcasting your automation from a station near you? If you are already using wireless, you have already plunged into the basics. But even if you are not currently a wireless maven, you are at least well aware that the topic is very much in the air—pun intended.

Is the technology new? Short answer: no, this is radio. Radio is a technology that has been in development since the 1890s. Hundreds of thousands of electrical engineers, ordinary people, even composers and movie stars have contributed millions of refinements to radio since its infancy. For example, in August 1942, Hollywood beauty Hedwig Kiesler Markey (Hedy Lamarr) and avant-garde composer George Antheil published an early U.S. patent describing frequency-hopping, spread spectrum technology. And the same basic technology—manipulation and harvesting of electromagnetic waves—is behind our cell phones, microwave ovens, radio controlled toys, radar, television and, of course, AM, FM and digital broadcast radio. Bottom line, regardless of the noise and the proliferation of terminology, wireless automation is radio.

Further, while discussion of wireless automation seems to quickly soar into the complex worlds of controller and enterprise networking, the radio itself is just the delivery vehicle. The electromagnetic pulses broadcast by a transmitter and harvested by a receiver are conceptually the same as the high-and-low electron flows sent via cables and circuit board traces in land-based systems. Granted, the type of radio governs how many pulses can be reaped in a given millisecond—and how the electromagnetic waves behave in earth’s atmosphere—but when you come down to it, wireless automation is about sending ones and zeros.

Having said that, there are, in fact, complexities in the details. Wireless solutions differ depending on application. And here, as in every other aspect of automation, vendors seek ways to differentiate their offerings, so there are features to sort out. For the most part, however, the technologies involved in radio are well-established, and perhaps more importantly, the radio world has been standards-based almost from the start. Most of radio’s standards are around the two interrelated facets of its world: the clearest possible reception of a signal and best practices for the prevention of interference.

The term “wireless” captures 95 percent of its benefit: it provides communications without wires. Festoons, slip rings, sliding contacts, conduit, wire runs (and, of course digging through wood, plasterboard and concrete)—all these and more recede into the background when you use wireless technologies.

Unfortunately, when you begin thinking wireless in automation, the biggest challenges are, one, so much has been accomplished on so many facets, and, two, every detail of radio technology has accumulated details as this or that wrinkle has been ironed out. There are a number of interrelated concepts—for example, wavelength vs. data rates vs. interference (short form: the longer the wave, the less problem with walls and trees, but the less data per second—of course, with dozens of provisos and qualifications).

For those plunging into wireless for the first time, the most significant source of anxiety is likely to be the alphabet soup—or, better, alphanumeric soup—of radio nomenclature. Some of the descriptors indicate the frequency band used for transmission (for example, 900 MHz or 2.4 GHz—that’s megahertz and gigahertz, for the uninitiated); some pinpoint the transmission and reception technologies (for example, frequency-hopping spread spectrum). Some are standards-based (e.g., IEEE 802.11x, in reference to a common wireless standard from the Institute of Electrical and Electronics Engineeers). Some of the terminology derives from a related sensor or controls protocol (for example, Wireless Hart), some from the computer consumer world (Wi-Fi, short for Wireless Fidelity) or computer networking (wireless Ethernet). Finally, some terms have even joined the soup from application domains (e.g., wireless SCADA, for supervisory control and data acquisition).

Thus, almost every radio component will have a profusion of headings in its specification sheet: a standards moniker (e.g., IEEE 802.15.4), what we might call the street name (e.g., Wi-Fi), network reach (e.g., WLAN or  WWAN, for wireless local area network or wide area network), automation moniker (e.g., DeviceNet), and so on. The Wireless Landscape diagram at right, provided by the Instrumentation, Systems and Automation Society (ISA) helps bring this confusion under control.

There are a couple of take-aways implicit in the diagram. First, there is a useful convergence of low-power usage, low cost, and low data rates embodied in the IEEE 802.15.4 standard. ZigBee and the soon-to-be-released WirelessHart equipment are found here. The low data rate is ideal for monitoring sensor setpoints and triggering actuators with requirements for momentary or relatively sporadic control. ...