LonWorks Solution Dramatically Cuts Wiring Costs for Microsmith CustomersLocated in Scottsdale,Arizona, Microsmith develops and manufactures industrial distributed control peripherals.The company is a subsidiary of Numatics, Inc, a global manufacturer of pneumatic valves, cylinders, and other types of pneumatic products. Microsmith implemented a LonWorks control network for the P. D. George Company and cut its installation costs in half. According to Willy Smith, president of Microsmith, "Our previous proprietary RS-485-based network only accepted devices compatible with the ones we manufactured. Our customers, however, desired increased flexibility when configuring their networks." In addition, a network that uses a large number of wires is very costly to operate and maintain. "The complex wiring hampered our efforts to locate and fix problems during faulty network operations," states Smith. Plant operations could also be affected by lightning damage to the semiconductor front-ends on the network nodes. "Lightning can easily damage or destroy chips," explains Smith. For Microsmith, a viable solution required several key design goals. "They needed to greatly reduce the costs and complexity of their current wiring set-up," says Smith.Another objective was to develop a modular approach that would offer a "plug-and-play" capability for customers as their networks expanded. "We also wanted to provide more robust network nodes," comments Smith. "A transformer front-end not easily damaged by static seemed the appropriate design for a substantially more reliable network." Microsmith Signals Support for Echelon Control NetworkAn advertisement for Echelon products caught Smith’s eye in late 1990. "Echelon offered a cost-effective yet complete solution," states Smith. "In fact, the company carefully considered all aspects of developing a viable control network." The typical network configuration that incorporates Microsmith products and LonWorks technology connects valves and temperature controllers used to manufacture semiconductors, automobiles, appliances, and other types of production facilities requiring distributed control capabilities. The LonWorks control network is responsible for executing a sequence of operations and performing diagnostics. For example, in a dyeing process, when a temperature controller reaches a preset temperature, that information is sent to the appropriate tank. "This tank may contain a dye used in the process," explains Smith. "The dye requires a specific temperature to achieve the correct color, which is applied to a component resting in the tank." The output valve is instructed to wait a set period of time before releasing the fluid in the tank, which is then drained away.The control network also continuously monitors the valves and temperature controllers and transmits alarms as necessary to a centralized monitoring PC. Remote Monitoring Capability Ensures Continuous OperationThe LonWorks technology has been especially helpful to the P.D. George Company, a Microsmith customer based in St. Louis, Missouri. Founded more than 75 years ago, the P.D. George Company is a premier global supplier of specialty polymers for the electrical and electronics industries.According to Victor Smeenk, chemical engineer at P.D. George, "The Echelon control network plays a key role in operating our reactors and thinning tanks." The company’s network configuration consists of more than 200 LonWorks devices including temperature, level, and pressure transmitters; on/off valves; control valves; motor starters and switches; variable speed drives; and heat trace controllers.All devices are daisy chained together in a 78 kbit/sec free topology architecture. Most of the 75 on/off pneumatic valves are used to control various liquid raw material flows from storage tanks to the reactors and thinning tanks.The LonWorks control network continuously monitors the valves, transmitting messages from a supervisory computer and providing valve position feedback to the computer.The remote capability means that only one operator is required to control all the valves and ensure that they are operating correctly. The P. D. George Company Slashes Installation Costs in HalfThe Echelon solution significantly reduces wiring and associated installation costs for the P.D. George Company. "The LonWorks free topology network enables us to daisy chain the valves together, so that only four wires are required for the entire network configuration," states Smeenk. "We no longer have to rely on an unwieldy mass of wires." He estimates that the company saved at least 50 percent of the installation costs as a result. In addition, Smeenk’s team can now easily obtain feedback on the operation of the valves. "Our previous approach required four more wires leading to each valve and two additional I/O modules to accept the limit switch feedback," explains Smeenk. "The extra installation and equipment costs were not worth the expense.The LonWorks based solution enables us to obtain feedback for free." Another key advantage is the ability to rapidly pinpoint and resolve problems. "A complex wiring system significantly impedes troubleshooting efforts,’’ emphasizes Smith. "The programmability of LonWorks based devices allows some of the logic to be pushed down to the device level.This can be used to provide local response during a fault condition," continues Smith, "and therefore keep the complexity of the main control program down, since these functions are usually the same for any device. As a result, network traffic is reduced because fewer changes inside the valve logic need to be propagated back to the central controller." Key Benefits• LonWorks control network cuts installation costs by 50%
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