01 April 2002
Wireless control? OK, if 'slow' and not critical...
By Jim Strothman
IEEE 802.11b and Bluetooth winning plant floor vote
While traditional hard-wired technologies continue to reign supreme running critical, deterministic manufacturing control applications, standards-based wireless technologies are winning new friends elsewhere on plant floors.
BP refineries going wireless
Petroleum and petrochemical giant BP PLC is implementing wireless mobile computing systems at BP locations worldwide, including the U.S., Singapore, the U.K., and Venezuela.
The BP refineries produce millions of barrels daily of petroleum products. Each location measures several hundred acres. One Texas location ranked among the three largest refinery sites in the U.S., requires one of the largest wireless handheld technology installations ever to cover its nearly 2 square miles.
Holtsville, N.Y.-based Symbol Technologies' wireless mobile computing systems should streamline facilitywide data communications at each location. Symbol's terminals and wireless network provide a data collection infrastructure to transmit and receive information critical to daily operations, in real time.
Bar codes affixed to thousands of pieces of refinery equipment quickly access detailed data on the history and condition of the equipment. Workers scan the bar codes on multiple daily shifts to collect and input process and condition monitoring data.
Symbol business partner Systems Application Engineering, Inc. developed the commercially available software platform for BP's maintenance workforce. Armed with real-time access to equipment data, users can quickly determine if and when equipment maintenance should be performed.
In geek speak, the Institute of Electrical and Electronics Engineers (IEEE) created a family of specifications called the IEEE 802.11b standard for wireless Ethernet LANs in the 2.4-gigahertz bandwidth space. English-language users can think of IEEE 802.11b as a way to connect computers and other gadgets to one another and to the Internet at very high speed, without any cumbersome wiring and at a relatively low cost.
802.11b is basically the same networking technology information technology departments use, so equipment interoperability is rarely an issue.
Bluetooth uses short-range radio frequencies to interconnect electronic devices, including PCs, mobile phones, and other electronic devices. Bluetooth is slower and has distance limitations. Wi-Fi champions, including some 110 companies belonging to the Wireless Ethernet Compatibility Alliance, support a Bluetooth special interest group, and Wi-Fi products are expected to coexist with Bluetooth designs.
"Bluetooth and 802.11b are achieving critical mass," said Sandy Harper, Parker Hannifin senior research and development (R&D) project engineer and the company's wireless solutions project manager. Harper helped Parker pneumatic valve experts in Sweden (Bluetooth's homeland) develop a Bluetooth-controlled wireless pneumatic valve island demonstrated at the 2001 Hannover Fair.
The typical industrial environment has thousands of access points for potential replacement with low-cost wireless sensors. For example, in one industrial valve control system under development at Parker, 14 tiny Bluetooth wireless sensors will replace 14 cables, 28 connectors, and eight I/O modules.
However, "Bluetooth is not yet real time-not deterministic," Harper said. "So for fast control systems, it's not applicable. For slow control, where you have 20 milliseconds or more, it's OK. Motors are fast. Pneumatics and hydraulics are not extremely fast. We're active in a Bluetooth special interest group, and deterministic control is viewed there as the Holy Grail. We're not there yet but maybe later."
Cahners In-Stat Group expects worldwide revenues from 802.11b equipment to surpass $2 billion by 2004. It forecasts the market for Bluetooth-enabled equipment to hit $5 billion by 2005, with the bulk of the opportunities in telecommunications, personal computing, and office and retail environments. However, Parker, Rockwell Automation, Iconics, and other vendors expect a sizable demand from industrial markets as well.
Wireless control and data acquisition applications are already happening.
Doug McEldowney, Rockwell Automation's NetLinx strategic marketing manager, said a Kentucky coal and lime plant that receives and transports more than 5,000 tons of coal per day uses a wireless EtherNet/IP LAN with spread-spectrum radio transmitters to send information between its ControlLogix remote I/O stations and a processor in the control room.
The coal plant, a complex operation that consists of 14 conveyors and belt feeders spread out over miles of terrain, set up three 80-foot towers to mount wireless antennae and ensure interference-free communication. Engineers also installed three separate EtherNet/IP subnetworks to increase the effective bandwidth.
Personnel can operate the system from two places: the coal handling control room and the station's main control room. A PC-based RSView 32 human-machine interface (HMI) station is located in the coal handling building.
Iconics president and founder Russ Agrusa said he is seeing interest in wireless technology for a wide range of applications: oil and gas pump fields, airport baggage handling systems, warehouse conveyors and other material handling equipment, building control systems, water/wastewater plants, automotive test stands, even Disney World. However, most are in data monitoring categories rather than control.
Chevron is using Iconics' Pocket Genesys 6.1, which connects with any OLE for process control server and runs on all pocket PCs, to help monitor 2,500 oil pumping stations at an oil field near Bakersfield, Calif., he said.
Cell towers about a quarter-mile apart provide full coverage for the 25-square-mile oil field. Maintenance personnel in cars use the handhelds to monitor data from individual pumps.
Continental Airlines in Houston is using Iconics' mobile technology to monitor baggage zipping from point to point on high-speed conveyors. "If a bag gets stuck in the conveyor system, they can see it on their pocket PC and fix it," Agrusa said.
Wireless technology can also track boxes on warehouse conveyors; monitor and control heating, ventilation, and air-conditioning systems on campus-sized complexes; control salt and chemical levels in water; and monitor engine performance on automotive test stands. Disney World is considering outfitting maintenance people with wireless technologies to monitor ride equipment and reduce downtime.
In addition to conveyor belts, other materials handling systems, such as overhead cranes, loom large as potential markets for wireless control. McEldowney said Rockwell took part in a site survey for a steel mill. There, "an operator sits in a crane and moves loads from point A to point B. In between, he does a lot of sitting around and waiting. The mill wants to provide some remote access so the operator can do diagnostics and maintenance on his equipment while waiting."
"There's a tremendous amount of wiring in industrial plants. Where you can simplify it, you can save a lot of money," Harper said.
Eliminating miles of cables and wiring should prove attractive to industries such as food and pharmaceuticals, which require ultraclean environments and "don't want nooks and crannies, where dirt can collect," Harper said.
Also, "data can be collected [wirelessly] from behind a glass wall. You can monitor something like a filter in a clean room from the outside. You don't have to worry about going in, which can be very time consuming."
Improved wireless technologies have reduced prior technical concerns. For example, by operating in the 2.4-gigahertz bandwidth space, "background noise" in lower ranges is not an issue. Also, frequency hopping, a technology credited to actress Hedy Lamarr, vastly increases the odds of a clear signal getting through.
Vendors making wireless equipment are encountering one problem, however, that is supply and demand related.
"We first initiated our wireless program two years ago, and it took six months to get going," Harper said. "Electronic hardware is still in its infancy. We have orders for components in low-power systems, but the telecommunications industry was ahead of us and has first dibs on components as they are made. We're behind them with our ideas." WBJ