The Need for Speed (on Wireless Networks for Control)
Currently there is a limitation to do true contol with wireless technology. What are the barriers we face to get to true control with wireless?
If we had the capability today I would be interested to know how many would use it, for what types of control, and why?
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Also at the Emerson Exchange
Also at the Emerson Exchange this fall, there will be a demo showing control of a distillation column with WirelessHART devices. The demo will be at the "Wireless Pavilion" during the Technology Exhibit.
Control Using WirelessHART
At Emerson Exchange this fall two presentation will be given on installations where WirelessHART is being used in control applicatiions:
Stripper and Absorber Control Using WirelessHART Transmitters - discusses how WirelessHART flow and pressure transmitters were used in steam flow and column pressure control.
WirelessHART Benefits Single-Use Disposable Bioreactor - presents detail on how WirelessHART pH and temperature transmitters were used in the pH and temperature control of a bioreactor.
WirelessHART was designed to support control applications. The exception reporting that is defined by the WirelessHART specification allow quick updates as the process responds to load disturbances or setpoint change but minimizes the number of transmissions required during normal operation. For example, the number of transmission in the absorber flow control example were reduced by a factor of 8X using exception reporting. To effectively utilize exception reporting in PID control, the reset calculation should take into account that the control parameter is not being updated on a periodic basis. This is a standard feature in DeltaV v11.
If you would like to learn more about how WirelessHART is being used in control, then you may the following presentations and paper to be of interest.
Greg McMillan, “Is Wireless Process Control Ready for Prime Time?”, Control, May, 2009
Scott Broadley, Bob Karschnia, Mark Nixon, Terry Blevins “Using Wireless Transmitters in Single-Use Disposable Bioreactor Control”, IFPAC Conference, January 25-28, 2009, Baltimore, Maryland, U.S.A
Greg McMillan, Michael Boudreau “Techniques for Wireless pH Control of Bioreactors”, Interphex Conference, January 25-28, 2009, Baltimore, Maryland, U.S.A
Mark Nixon, Deji Chen, Terry Blevins, and Aloysius K. Mok, “Meeting Control Performance over a Wireless Mesh Network”, The 4th Annual IEEE Conference on Automation Science and Engineering (CASE 2008), August 23-26, 2008,, Washington DC, USA.
Chen, Nixon, Blevins, Wojsznis, Song, Mok “Improving PID Control under Wireless Environments”, ISA EXPO2006, Houston, TX