By Jim Montage, Executive Editor
Is radio frequency identification (RFID) for real? If it isnt already, it might be soon.
Once viewed as a mirage appearing somewhere between old-time radios and more-recent barcodes, RFID appears to be carving out a niche for its tags, transceivers, antennas, and software. Never mind that RFID tags are still far more costly than barcodes, or that radios still offer better performance and data handling capabilities. Almost by sheer force of will, some suppliers and users are driving increasingly varied RFID methods onto the plant floor.
Now that the hype of Wal-Mart and U.S. Department of Defense mandates have been scaled back, and had a couple of years to die down, RFID supporters are trying to develop and deploy practical, cost-effective applications.
Still, skeptics view RFID as a documentation and material-handling technology that has no real place in the sense/decide/act triangle that defines control and automation. However, fans say there are many ways for RFID to participate in communicating position and physical property data.
For example, visitors to the recent 2007 Siemens Automation Summit in Orlando, Fla., were surprised to see their names flash on screens as they approached the hall entrance. They learned that pre-programmed, 928 Mhz UHF tags embedded in their name tags were setting off Siemens E&As RFID antennas near the doors, which triggered identifying information for display on the screens.
RFID technology has been in existence for 20 years, but its just starting to make its presence felt in mainstream, industrial applications, says Filomena Wardzel, Siemens E&As automation business manager. The amount of information RFID can capture and transport is growing, and were starting to see benefits. For example, a tag on one item can tell where and when it was made, purchased, consumed, and even discarded. Despite the development of 2-D matrix technology, RFID tags still can contain 10 times more information than any barcode.
Despite these benefits, in his recent Current Trends in RFID report, Helge Hornis, Ph.D., intelligent systems manager, Pepperl+Fuchs, warns that RFID tags need protection on the plant floor. For a tag to be useful in the manufacturing environment it must be housed to withstand aggressive fluids, shock and vibration, dirt and grime, and possibly elevated temperatures, he says. These tags also are expected to operate for many years in abusive applications. And is 99% read reliability really enough for the manufacturing environment? With this in mind, its highly doubtful that a tag satisfying the needs of the industrial sector ever will be available for 25 cents. While the cost of the chips used in tags will continue to come down, most of the cost is tied to construction and housing, and its unlikely those prices will experience reductions.
Hornis adds that potential users also must be aware of the differences in high-frequency (HF) band and ultra-high-frequency (UHF) band RFID systems, and that they must determine how far away their application will be trying to sense tags, or if theyre risking repeat sensing of tags grouped too closely together. They also must decide what read-write capabilities they need.
Any suitable RFID solution for the plant must offer reliable, easy connectivity to the dominant networks supported by PLCs. DeviceNet, Profibus, and Ethernet are the most important industrial networks used with RFID technology today, says Hornis. Among the networks used for automation RFID, Ethernet is clearly the hottest, so Pepperl+Fuchs recently designed an RFID controller that simultaneously supports the Ethernet flavors introduced by Schneider Electric, Siemens and Rockwell Automation, he adds. With Modbus/TCP, Profinet I/O, and EtherNet/IP implemented on the same hardware, users finally can learn it once to address their RFID needs. For users who toyed with the idea of using RFID a few years ago, but decided against it for one reason or another, its time to take another serious look.
Likewise, Turck recently introduced its BLident modular RFID system with built-in I/O capability, reports Mark DiSera, Turcks network and interface products manager. BLident lets users add I/O modules, including up to eight RFID channels on one gateway and additional discrete or analog I/O comprising one node on the network. Built on the ISO15693 13.56MHz HF standard for an open system, BLident can be integrated into existing platforms, and supports Profibus-DP, DeviceNet, Modbus-TCP, Profinet, and EtherNet/IP.
