Late last year, produce grower/marketer Mills, Inc., of Salinas, CA, established wireless communications between a plant PC and four Diagraph ink-jet printers (see story on p. 17). In doing so, the firm became one of the first to bring wireless connectivity to the world of packaging machinery.
“There’s a transmitter at the PC and a receiver at each of the four ink-jet printers,” says Mark Tolhurst, director of manufacturing information systems at Mills. “The signals are sent like radio signals right through the air.”
Computer networking consultant Superior Tech Systems played a key role in designing and implementing Mills’ wireless solution.
“Because Mills moves its entire operation from one location to another based on harvest conditions, we had to make sure that anything we did electronically for data transmission and collection could be moved and set up again in less than eight hours,” says Superior Tech’s Scott Scribner. “That’s why a wireless solution was so appealing. What we do is collect data from and send signals to the Diagraph printers via a wireless Ethernet connection. It’s the same 802.11b protocol used in home and office networking.”
Scribner says he opted for point-to-point wireless connectivity, which means four individual wireless networking cards in the PC, each dedicated to one Diagraph printer. A multipoint arrangement—one radio communicating with all four Diagraphs—might have left room for interference in the radio signals being sent.
Like just about any IT connection these days, the one at Mills is already being eyeballed for improvement. Next up, says Scribner, is the adoption of 802.11g, a new wireless protocol that is said to be five times faster than 802.11b.
Also being studied is the use of remote desktop software to turn a handheld Personal Digital Assistant (PDA) into a wireless extension of the PC that controls the Diagraph printers. This will simplify the setup considerably, because right now the PC controller has to be inside the refrigerated room where the produce is packaged. To protect it from possible damage caused by condensation, it’s encased in an insulated “ice box.” The use of a PDA will obviate any need for the ice box.
