Mention RFID (radio frequency identification) to many people and the first thing that comes to mind is Wal-Mart’s application of the technology. Since Wal-Mart is associated with low cost, its use of RFID to track products directly associates with cost savings in its operations. Wal-Mart’s size makes it easier to justify the effort. However, they are certainly not alone. According to the RFID IEEE Survey Report Spring 2007, respondents from a variety of industries indicated that over 60 percent were at some point in implementing RFID from pilot planning to limited or even full implementation.
Implementing any new technology can have problems and RFID is certainly a complex area that can challenge even the experienced engineer who is not familiar with it. According to Gene Fedors, vice president of education programs at the RFID Technical Institute, “If you don’t understand the science/physics behind RFID, you are not adequately equipped to undertake a program.” Even Wal-Mart has had to regroup from its goals for RFID adaption stated in 2003 because of implementation difficulties with its suppliers. The key to success, as in many other instances, is working with a partner who has the required expertise.
Without guidance, the available technologies for RFID require extensive investigation to determine the appropriate choice. According to the IEEE survey, the top three choices used by global companies were Gen 2 (18 percent), low-frequency (18 percent) and high-frequency (16 percent). Clearly, no one technology is an obvious choice and other possibilities including active, low-frequency, battery-assisted passive, microwave, surface acoustic wave and RuBee (IEEE 1902.1) add to the available options. Figure 1 (below) shows a comparison of the strengths and weaknesses of some of the frequency ranges for passive tags.
For industrial applications, many companies are opting to follow ISO 15693 standards for 13.56 MHz. This design provides power to the data carrier through an RF field using inductive coupling (passive RFID) and the frequency is outside the range of industrial interference fields. This frequency is also a worldwide standard for RFID manufacturing applications.
In an industrial plant, RFID provides higher product visibility, eliminates manufacturing errors, enables asset management, potentially can increase production speeds and has other benefits as well. In contrast to simple barcode tracking, multiple RFID tags can be read at the same time as they pass by the reader. In addition, since RFID uses radio frequencies, it is not restricted to line-of-sight reading that limits barcode readers.
Data storage is an important consideration for RFID tags. In general, the RFID tag can store as much as 100 times more data than a barcode. Equally important, information can be both written to as well as read from the tag. In addition to Electrically-Erasable Programmable Read Only Memory (EEPROM), the use of Ferroelectric Random Access Memory (FRAM) allows higher data transfer rates. As a result of reading and writing up to 0.5 msec at distances up to 200 mm, higher conveyor speeds can be used. Also, FRAM can handle more write operations, as many as 1 billion as opposed to EEPROM’s 100,000 cycles.
One of the more difficult parameters in industrial applications compared to more traditional RFID tracking is the temperature range. In addition to standard data carriers for temperatures up to 120C (248F), units are available for temperatures up to 210C (410F). This simplifies the application of the RFID tag and increases its potential usage.
An example of how RFID is making an impact in an industrial environment is demonstrated by its use in automotive assembly. A high temperature RFID tag goes with the vehicle chassis as it travels through the assembly plant including high temperature areas such as the paint shop where the tag withstands the temperature of the bake operation. The customized requirements for vehicles demonstrate one of the unique capabilities of RFID tracking. However, RFID is not just for automotive assembly. Any manufacturing operation that involves higher cost products where tracking is important can potentially use this technology.
A modular RFID system allows a complete system approach to RFID as well as easy coupling to other networks, including PROFIBUS-DP, ProfiNet, Ethernet IP, Modbus TCP and DeviceNet. With the ability to connect to field installable enclosure I/O products, instead of requiring a separate gateway for I/O and RFID, both can be handled by the same gateway with more I/O points.
Ultimately the application dictates the system requirements. To make the application of RFID technology easier, an RFID on-line configurator helps users match the amount of data, distance of the tag from the reader and speed. With this information, the proper tags, system components and options can be chosen.