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Advantages of wireless switches

Posted: 27 Jun 2011 ?? ?Print Version ?Bookmark and Share

Keywords:Limit switches? wireless? RF?

Limit switches have been in the market for decades, protecting heavy equipment and providing significant position information. They are used in everything from crane booms to gates, lifts to storage tanksanywhere there is a need to sense the presence, absence or position of a moving object. In a crane application, the limit switch is located on the end of the boom. The limit switch could be used to indicate to the operator when the cable jib is close to the end of the boom and it is not safe to spool the cable further.

In the last few years, limit switches have become enabled by wireless using technologies such as IEEE 802.15.4 to transmit information from the remote switch to a receiver, which then converts the signal to ones used by standard controllers. Converting switch solutions to a wireless mode addresses a variety of customer needs for lowered cost and increased limit switch installation options, giving early adopters a competitive advantage in the design of next generation industrial and transportation equipment.

Benefits of wireless switching
Wireless limit switches can lower equipment costs in a variety of ways. For one, the cost of manufacturing and installation is reduced. Not only is the expense of wiring eliminated, there are no conduits, clips or connectors required to place a limit switch where it is needed. There are no wire routing problems to solve, no need for pulling wire during installation and fewer restrictions on location and placement of the limit switch.

Wireless limit switches can also reduce maintenance costs. Equipment wiring is less complex with the elimination of wired switches from the mix, simplifying troubleshooting and reducing commissioning time. Further, going wireless increases system reliability by eliminating the potential for having continuity issues with switch wiring or connectors. Switches also become simpler to replace, with no need to disconnect and re-attach wiring and no risk of incorrect wire attachment.

Global limit switches are an essential element of industrial and transportation controls, monitoring position and presence of doors, booms and valves. Conventional wired switches, however, present installation and maintenance challenges, especially in installations that are subject to harsh environments or involve frequent flexing in the wiring. In some cases, traditional wires can represent tripping hazards or can be compromised during normal equipment operation, thus causing expensive machine down-time.

Wireless technology
During the last decade, the telecommunications industry has made phenomenal advances toward replacing wired connectivity with wireless. As the technology evolved, it overcame both technical challenges and political barriers to deployment. A variety of fully defined and robust networking protocols emerged that function well over these wireless technologies. Government agencies worldwide settled frequency allocations and regulatory issues to allow worldwide operation of those wireless networks.

These advances in wireless telecommunications have opened the door for applications beyond telecommunications to "cut the cord" and to go wireless. For instance, one of the protocols that arose, the IEEE 802.15.4 standard, fully defines a robust wireless personal area network (PAN) that specifically targets low-power, low-bandwidth signaling from switches such as those commonly utilized in industrial monitoring and control. Further, wireless telecommunications spurred semiconductor design and manufacturing to develop highly integrated, low-power RF components for wireless communications.

As a result of these achievements, it is now possible to cost effectively convert a basic component in industrial monitoring to wireless: the limit switch. The advent of wireless limit switches also provides equipment developers with an expanded range of applications. By using wireless, designers can now place switches in locations where it is impractical or impossible to run wires back to the control console. They also can increase their design's flexibility by allowing switch positioning to adapt to installation requirements, even if that position must be modified over time.

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