It's a daunting challenge to convince design engineers in conventional industries, such as appliances and vending machines, that wireless communications technology is both beneficial and reliable. But component manufacturers continue adding features designed to overcome those roadblocks.
In areas such as laundromats with many washers and dryers or locations where several vending machines are scattered about, wireless links can provide a simple way to add remote diagnostics without the task of rewiring. Each machine can send status information and other data to a single collection system that relays it back to a central office via phone or the Internet. For example, sensors in a vending machine could send a warning message when the temperatures of the soda cans inside are going out of range.
That's the concept being promoted by companies like Xecom Inc. (www.xecom.com), which recently augmented its wireless module line with a new transceiver and base access point. These second-generation modules now support up to 128 nodes, communicating over distances up to 150 feet. They also provide more frequency options.
"Rather than having one frequency within the 900 MHz band, we now have up to 126 frequencies, so people can switch if there's a problem," says Steve Clary, VP at the modem supplier founded in 1983.
The new line also connects directly to analog sensors and control lines, eliminating the requirement for a microcontroller that was previously needed to communicate with sensors. Instead the module's microcontroller now has utilities that handle this task. Two analog inputs and four programmable digital inputs are provided.
While Clary cites these and other benefits of remote monitoring in these applications, he notes that the market is slow to rise. "This is a fairly new market, and it's a conservative field where a lot of people think Ethernet is really sophisticated stuff. They want to be sure the technology is absolutely bulletproof," he says.
Some vending machine manufacturers are now testing prototypes, though many of these companies are like automakers in that they do extensive life testing before adopting a new technology, Clary says. However, around a million vending machines are produced each year, and designs often have fairly long life cycles, making the market attractive, he adds.
Another added feature is "count-off," a time division multiplexing scheme that lets each node send an 8-byte status report during a predetermined time slot. Benefit: Check all 128 nodes in less than five seconds.