See our Wireless Guide at www.controlglobal.com/wirelessguide.html
Some have called it a coming inflection point in the manufacturing industry. Some have called it a curse and a potential weak spot perfect for cyber hackers to exploit. Many are waiting for the hype and the FUD (fear, uncertainty and doubt) Even more are confused.
Here we’ll try to clear up the confusion and help you find your way to the best use of wireless communication technologies in your plant.
We’ve spent the last two years learning about wireless, going so far as to join the ISA SP100 standards committee, and so we’re pretty much up to speed. We’ve even done original research—two surveys—for this article. The first (see sidebar “Survey Snapshots Wireless Users”), undertaken by Control under the auspices of SP100, details the responses of 499 end users over a four-month period. The second was a survey of attitudes toward fieldbus and wireless. It is available at www.controlglobal.com/fieldbusmarketreport.html. Both surveys are original, and the data is presented here for the first time.
We’ve also produced some web-based material that will help you broaden your understanding of how industrial wireless works. At various points in this article, we’ll refer you to the ControlGlobal.com website, where you will find videos, podcasts, and extended versions of parts of this article. For web-based information, look for the .
The important thing, though, is to keep focused on what wireless technologies will do for you. Will they make your job easier? Complicate it unmercifully? Help or hurt?
A Brief History of the Wireless World
Wireless communications in the industrial world grew directly out of the telemetry methodologies developed in the 1950s and 1960s for rocketry and space exploration. Very quickly, industries such as the power, water and wastewater utilities, and oil and gas pipelines discovered that they could use radio to monitor, and in some cases even control, their far-flung assets. Throughout the later 20th century, first with walkie-talkies and then with cellular telephony, end users in utilities, discrete manufacturing, and the process industries found ever more uses for wireless communications.
By the mid-1970s, SCADA systems in water/wastewater, oil and gas and utility service increasingly were using radio communications between RTUs (remote terminal units) and the SCADA head end (the main office), where there were repeater “panel walls” and, finally, computerized command-and-control centers. This writer’s first experience with wireless in SCADA was in 1976 doing a radio survey for a system installed by Northern California’s East Bay Municipal Utilities District for wastewater collection system pump stations. Wireless in control systems has been around for a long time.
The cost of leased telephone lines was the main impetus toward radio SCADA, but later, the lack of available frequencies made it harder to do, especially in developed areas.
All non-licensed industrial and commercial uses of wireless rely on a group of frequencies collectively called the ISM (Industrial, Scientific and Medical) band that were set aside by all governments to make possible the use of wireless for peaceful purposes. The ISM band is a relatively small group of frequencies, and cellular telephones, wireless telephones for home use, wireless Internet and all of the other uses you can think of, other than governmental, military, and emergency service uses, are part of the ISM band. The general rule is that no use of an unlicensed transmitter or receiver in the ISM band should interfere with the operation of any other. Remember this rule, because it is going to become important as wireless becomes more prevalent in process plants.
Wireless in Discrete Manufacturing
Many companies support wireless technologies devoted to the discrete manufacturing industries. Companies like ABB and Siemens have complete wireless networks designed and constructed for the discrete manufacturing sectors.
At the recent ABB Automation World, chief technology officer Peter Terwiesch pointed out that ABB has been a pioneer in wireless technology.“I don’t recommend wireless for critical closed-loop control,” he said, “but in discrete automation, it is very much the other way around.”
In the exhibit area, ABB had a completely wireless robotic manufacturing cell, which even had its power delivered wirelessly. Wireless motion control is very much alive and well in discrete manufacturing, as is RFID (radio frequency identification). Woodhead’s Ed Novotsky believes that this is where the industrial use of Bluetooth technologies will really take off.
Convergence and COTS
The IEEE has led a drive toward consensus convergence standards for wireless, and this drive has been incredibly successful. Most offices and even many homes have wireless networking technologies based on IEEE 802.11x standards. The ubiquity of “wireless Internet” has reduced the cost of components to very low levels.
COTS (commercial-off-the-shelf) wireless networking devices can be bought at pharmacies, supermarkets, hardware stores, and discount stores. Companies like Advantech, ProSoft, Cirronet, and many others make “industrially hardened” versions of theseCOTS networking appliances, and sell them into the industrial markets.