The pull of wireless technologies in manufacturing monitoring and control is strong. You can reach equipment whose motion or remoteness makes hard wiring impractical. You can integrate systems in which physical layouts, overstuffed cable trays or expensive trenching mean that wired alternatives add up to more expense than going to the airwaves. In general, you can add devices faster than is possible with wires, at least if your situation demands new wires.

That said, attaching names to specifics turns out to be hard—at the moment. Few want to put their names to applications. To be fair, the situation is influenced by the fact that wireless control and monitoring offers ways to do things that have not been done before, and some are concerned that speaking up might lose them competitive advantage. Plus, while a good many installations are relatively cut-and-dried, a significant number are literally moving into new territory, at least for the company who is being asked to talk about it. Until the bits and pieces of common experience coalesce into a more or less public body of knowledge, people have a right to be a tad uncertain about the glare of publicity.

But wireless is definitely at work, in three broad categories. The first is a long-established use of radio monitoring for point sensors or field instruments, found in a wide range of distributed systems, from electrical grids to remote sensor monitoring in a variety of manufacturing settings. While these are highly useful (and many have been in place for a long time), they tend to be one-way set-ups (from the sensor to the control system) and are generally not intricate.

The second category includes those installations in which a radio has become a virtual wire—that is, wireless transmission is taking the place of wired communications in a controller or computer network. These are a little more interesting from an automation engineering perspective.

Finally, there is general movement into new kinds of applications—or at least new kinds of benefits—stemming from new capabilities afforded by the technology. Like kids with new toys, engineers have found ways of expanding the envelope.

Still, even the basic, distributed radio-to-a-sensor set-up has interesting wrinkles, primarily because highly focused chips have become increasingly available. In addition, such infrastructure elements as self-organizing broadcast networks, or “mesh” networks, make for rapid deployment. As Robert Shear, director of market development for wireless chip vendor Dust Networks Inc., in Hayward, Calif., said of the latter, “WirelessHart and (the coming) ISA100 standards cover reliability and security issues, and self-organizing [radio transmission] networks adds the flexibility that plant people need. There are always going to be potential interruptions of wireless transmissions, and allowing every sensor the ability to seek and lock on to every possible route means that data can be delivered regardless of obstructions.”

A case in point of the strengths of self-organizing networks is provided by one Emerson Process Management customer, an offshore oil harvester. Emerson, an Austin, Texas-based process controls vendor, employs Dust Networks technologies in many of its wireless sensors. Off the coast of Norway, one of the hydrocarbon harvester’s oil rigs needed ways to monitor wellhead annular pressure, as well as heat exchanger pressure drop. Time pressures added to the challenges—when hard-wired, changes in monitoring required two days to implement. The wireless installation required two hours or less for changes, and the self-organizing network was immediately able to reach a wireless gateway placed above one side of the rig. Pre-installation concerns centered on the dense piping and labyrinthine metal structural elements of the platform: Would they interfere with radio frequency (RF) transmission?

In the actuality, there was no issue, since the sensors easily routed themselves to the access point. Instrument engineers went from a decidedly tentative attitude toward wireless to full confidence in the ability to put sensors in any needed location, and the rig’s wireless network continues to expand.

In the development of the kind of small, cost-effective wireless devices employed in the oil rig application, it hard to overestimate the long-range influence of custom chips. Dust Networks provides a single chip that is embedded in the Emerson devices. The chip combines complete, low-current RF circuitry that requires only an antenna connector, as well as self-organizing network capabilities that allow it to act not only as an end point, but also as a router.

In a similar approach, but with a slightly different focus, ConnectOne’s WirelessHart-compliant iChip line offers Ethernet wireless fidelity, or Wi-Fi, serial communications capabilities, and even a built-in Web server, suggesting ...