Rats, Danish royalty, and wireless
What do a 10th century Danish king and the common rat have to do with the move to wireless on the factory floor? The rat typifies the problems inherent with physical wiring. One of my OEM customers lost the Ethernet connection to a machine several years ago. Unable to find anything wrong with the equipment itself, he tracked the Cat 5 Ethernet cable back to its source.
What do a 10thcentury Danish king and the common rat have to do with the move to wireless on the factory floor?
The rat typifies the problems inherent with physical wiring. One of my OEM customers lost the Ethernet connection to a machine several years ago. Unable to find anything wrong with the equipment itself, he tracked the Cat 5 Ethernet cable back to its source. He lifted the ceiling panels to discover that a rat living in the rafters had chewed through the cable.
Nearly every company has experienced a shutdown like that, whether caused by rats or corrosion or carelessness. It's one of the reasons industry is embracing wireless technology.
Advances introduced by automation and control suppliers over the next few years will do much to alleviate the remaining concerns about the reliability of wireless technology. That's where King Harald Bluetooth comes in. Researchers at a number of Scandinavian electronics and telecommunications companies were responsible for much of the early development work in wireless technologies. They affectionately named their new short-range wireless standard after the Danish king.
Bluetooth provides a simpler way to allow all the electronic devices on the modern factory floor to talk to each other. The new Bluetooth standard lets any sort of electronic equipment—from computers to PLCs and drives—make its own connections without wires, cables, or any direct action from a user.
Bluetooth is intended to be a standard that works at two levels:
It provides agreement at the physical level—Bluetooth is a radio-frequency standard.
It also provides structure with regard to products agreeing on when bits are sent, how many will be sent at a time, and how the parties in a conversation can be sure that the message received is the same as the message sent.
More than 1,000 companies now participate in the Bluetooth Special Interest Group and are developing hundreds of new Bluetooth compatible products for consumer and commercial applications.
Bluetooth hardware is based on a very small radio module that can be attached to or embedded in a control device. Bluetooth communicates using a technique known as "spread spectrum frequency hopping" that is less vulnerable to interference than other wireless modulation techniques. Connecting is instantaneous, and there's no need to reprogram components or rewire production lines if requirements change. It's also inexpensive. Bluetooth doesn't require doing anything special to make it work. The devices find one another and communicate with little or no user input.
Bluetooth will become the short-range alternative to wireless Ethernet. With an effective range of up to 30 feet, it will be an ideal technology for providing secure operational productivity on the factory floor. Imagine the time that could be saved if you could monitor or reprogram a PLC or drive without opening a control panel or returning to a central control room.
With the rapid introduction of Bluetooth-enabled control devices that can be expected over the next few years, network or software compatibility will become less of an issue. That's important for operators or control engineers, and for the plant engineering staff that have had to maintain, update, and pay for costly automation software license renewals every year.
Adoption of Ethernet, Bluetooth, and other open wireless technologies means monitoring and controlling the devices in automated manufacturing systems will become as simple as making a cell phone call is today. The reduction in engineering time and costs these technologies are making possible will significantly improve manufacturing productivity in every industry.
Valerie L. Tur is a senior application and control engineer with Schneider Electric;
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