Commentary: Wireless for process moves beyond instrumentation
Systems for process plants are evolving to include more bidirectional functionality.
By Control Engineering Staff
At its recent Honeywell User Group (HUG) the company set out to prove that an entire process unit could be built with no wired devices, except for power in some cases. While the process in this case was nothing more than pumping water from one tank to another, it did involve an impressive number of devices, including a pump, control valve with indicator, radar level gage, pressure sensors, temperature sensor, equipment health monitor for the motor, and a few others. They were not all input devices, several were actuators that required bidirectional communication.
All of this was tied to the controller via a single wireless network with no data cabling to the control system at all. Even the HMI was wireless, including a second walk-around control device via a tablet PC. A few devices had external power, such as the pump and radar level gage, but that was it. While wireless instrumentation has been the area that has generated the most discussion--and often controversy--the idea of doing all communication over the air, regardless of whether it’s input or output, has been slower in coming.
Andrew Nolan, network and wireless consultant for Honeywell, was responsible for designing the display. He explains, “We weren’t trying to show a real process as much as showing that we can do work wirelessly, with input, output, monitoring, HMI, controller, and all those different pieces. The tanks were there to provide a platform for all the different applications that we had.”
While the demonstration was all one system, more than one wireless protocol was in use according to appropriate bandwidth requirements. This concept of using the right tool for the job has been part of the OneWireless system from its launch. The instrumentation and discrete outputs use the ISA-100 ready system that Honeywell is adopting for its devices. The HMI and walk-around control use wireless Ethernet.
I don’t think that Honeywell is the only company that could build such a demonstration, but I suspect no other could have done it with so much of its own equipment. The company certainly seems to have set out to create as wide a wireless system as possible under its own brand, from individual instrumentation devices on up. Others that are concentrating more on one segment of the system will likely also broaden their offerings as demand grows.
“It’s interesting to follow the evolution of industrial wireless,” Nolan adds. “When it first came out, it was strictly monitoring or SCADA type applications. Back then if you asked about wireless control, you got‘no way, we’ll never do that sort of thing.’ By now, all doubt that we will do wireless control is gone—it’s just a question of when. We’ve certainly shown that for the types of processes that can stand one-second latency, wireless is not only feasible, but with ournew R120 release with the redundant gateway, we can do it with no single point of failure. With that kind of reliability and one-second reporting, it’s very appropriate to talk about wireless control. Everything we showed in the demonstration can be done redundantly now. Wireless control is ineverybody’s future.”
Such developments and demonstrations are critical if process users are to move past the idea of wireless being for just instrumentation. The idea that wireless can cover any type of communication that wire can, and probably a whole lot more, is growing. When the communication medium is forgotten and we think only about the exchange of information, that will indeed be a major advance.
Read The Transparency of Wireless .
—Peter Welander, process industries editor, PWelander@cfemedia.com
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