More than one way to go unwired

More than one way to go unwired Not all wireless links are based on Ethernet. Serial wireless can be a simpler alternative. Say the words "wireless link" today and most technologists start thinking about Ethernet wireless protocols. Ethernet has certainly become ubiquitous. But it is not necessarily the best way to implement a link either to remote facilities or mobile platforms. Wireless connections that don't involve transferring a lot of data can often get by with a radio link rather than an Ethernet connection. The typical term for such systems is a wireless serial-communication system. These systems typically communicate using spread-spectrum radio signals in the ISM 900-MHz or 2.4-GHz band. The configuration often used is that of one master station connected with a number of slave stations which contain a combination of input and output points. Examples of such systems include one from Omron Electronics LLC, Schaumburg, Ill., called the WT30 and Trusted Wireless systems from Phoenix Contact Inc., Middletown, Pa. Omron officials say such systems often find use on mobile applications such as AGVs and on factory equipment that gets moved around and reorganized frequently. Here wireless setups can be alternatives to delivering data signals via slip rings or installing guide lines in a factory floor. The Trusted Wireless equipment operates in a similar manner though it incorporates a means of getting to remote facilities via phone lines. Of course, serial links of this nature have their limitations — you wouldn't want to use them for streaming YouTube videos. Similarly, data from an industrial vision systems would overwhelm a serial link. Serial systems like that from Omron operate at 115,000 bps compared to about 54 million bps for WiFi. But the lower rate is adequate for handling ordinary machine I/O. Omron puts the upper limit of its system at 1,000