difference between factory and process automation involves need for wireless mesh, or multi-hop networks, says Read. While mesh networking is called out in process-oriented wireless standards, mesh is often not needed in factory automation, he says, and may, in some applications, be detrimental. “For the most part, what we’re looking for is a short distance between two points, where you’re just replacing a wire for a moving part. The controller is right in the vicinity of the end device, so we don’t need to mesh that across hundreds of feet to the other side of the plant,” Read explains.

Unlike the process world, in which sensor and instrumentation data is often brought back to a central point, discrete manufacturing tends to have more distributed architectures, Read continues. “We’re not running as one big process. We’re running as multiple, small discrete processes.” In a robot work cell, for instance, multiple robots typically all have their own controllers that are having their own conversations with their own end effectors, or the programmable logic controllers that are managing them, Read notes.

This means that any factory wireless standard will need to accommodate these multiple transmissions within a relatively small, physical area while avoiding interference. Standards such as 802.11g offer ways to do this through use of nonoverlapping channels, says Read, while the new 802.11n version of the standard, published last October, will offer even more opportunities for channel separation.

Not waiting

Despite a variety of RF devices currently on the market that may potentially meet factory automation needs, they are not currently interoperable, so development of a standard is vital as a way to ensure multi-source availability, Read emphasizes. But even without a standard, Read says he has heard of some end-users who are already deploying wireless control for robot end-effectors. And if a standard can be put in place, he expects that discrete manufacturers would move quickly into broader use of wireless for factory control.

“Once we’re able to demonstrate that these are reliable devices, and that they’re deterministically providing updates, I don’t see a reason not to fully jump into it as an input and output media,” Read concludes.

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