Imagine a radio frequency identification (RFID) label replacing or supplementing a barcode. Now, imagine that this RFID label is permanently attached to a pallet, a snowboard or even a PC and that the RFID label can be used from production to retail. RFID systems are now providing the data capture foundation for supply chain systems. RFID tags can be attached directly to products or transport carriers, providing the products with intelligence. �Intelligent� products will now instruct manufacturing on how they should be built or communicate to logistics on how they should be distributed.
What is RFID? Historically, a transponder (commonly called an RFID tag), which contains a coil antenna and a programmed silicon chip, is used either as an identifier or to contain larger amounts of variable data. Tags come in a variety of sizes, memory capacities, temperature survivability and read ranges. Certain tags can be small enough to inject into animals or can be the size of a desktop for long-range applications. Nearly all tags are encapsulated for durability against shock, fluids, dust and dirt. While tags are immune to most environmental factors, their read/write ranges may be affected by close proximity to metal and electromagnetic radiation.
RFID � The basics
An RFID system involves tags, antennas and controllers, which can be either passive read-only, passive read/write or active read/write systems. In its most basic read-only form, RFID is an alternative technology in environments too harsh or dirty for optical barcode systems. The read-only tag consists of a small integrated circuit with a fixed code and a small coil or foil antenna. The tags are usually powered by the RF signal from the antenna. The systems also use a variety of RF carrier frequencies from very low frequency (50-500KHz) to microwave (0.9 -2.5Ghz). The application architecture of read-only systems is very similar to that of a barcode system, whether in a manufacturing or distribution environment. Read-only tags are particularly useful in asset identification since their identifiers cannot be changed.
The passive design of a read/write system uses the RF field from the antenna to power the tag, eliminating the need for batteries to power the response, although batteries may be incorporated to maintain memory. Tags from different manufacturers vary in the time they take to power up and respond, a fact often overlooked but extremely important when researching passive systems.
A process using read/write RFID can continually update information in tag�s memory, keeping a record of the process that can be acted upon immediately or uploaded later for analysis. The data remains with the product or container, providing a new, simplified concept in flexible manufacturing and distribution where host computers are no longer involved in the low-level management and exchange of information on the shop floor or warehouse. The data residing in the tag�s memory can be accessed by the host system when necessary for global management functions, while other functions are carried out at the local level by handheld readers or the RFID controllers.
Active read/write tags are powered by an internal battery and are generally larger in size than passive read/write tags. Encompassing all the properties of passive read/write systems, active systems typically employ advanced digital signal processing techniques that allow data transmission speeds of 3,000 bytes per second of fast, random access memory. Active tags typically have greater range than passive tags, although achieved or allowed range is dependent on the frequency range of the system and regulatory issues.
RFID � The next generation
While existing systems have been used successfully in a wide range of applications, a new generation of RFID tags is coming into even wider use. Passive read/write systems adopting Philips Semiconductor 13.56 MHz (ICODE based) frequency have quickly become the supply chain RFID solution of choice. Tags no longer need to be encapsulated. In fact, RFID tags need not be tags at all, but now take the form of paper or polyester labels, which can be adhesively applied to any product imaginable. The Italian Post Office has adopted such a system for its mail sack tracking application.
These new tags do not contain miniaturized radio stations as have previous generation tags. They operate on a different technology called �backscatter,� which not only allows for much smaller tags but greatly reduces costs as well.
Antennas can now read and write data to hundreds of labels at once. For instance, the Italian Post Office RFID application, the first such RFID installation in the world, can read/write informa-tion up to 24 labels as they pass through the tunnel antenna (the labels are inside the mail sack) and all the labels can be identified in seconds. Each tag is a unique entity and different information can be written to each tag, if required.
In addition to passive read/write RFID labels, printed circuit boards (PCBs) can be used for more environmentally challenging applications. In the first of its kind, one of Europe�s largest pallet manufacturers is embedding an RFID PCB directly into a pallet. Using a robotic arm and PCB dispenser, each PCB is placed inside a plastic pallet before it is ultrasonically welded together. The RFID PCB will now be permanently part of the pallet and can be tracked from location using industrial antennas. Pallet companies routinely lose millions of dollars each year in unreturned and misplaced pallets. By embedding an RFID PCB inside the pallet, the company can determine where the pallet was last shipped and cross-reference this to the returned pallets. PCBs are preferred in pallet tracking applications over RFID labels, since the pallet production process requires the tag survive high temperatures. PCBs can also be used for tracking wood pallets.
Although not yet widespread, pallet identification offers tremendous opportunities for shipping and receiving operations. While pallet owners can be assured of being able to track their assets, the identification codes in the pallets could also be used to identify shipments in 856 EDI transactions. Because RFID is truly �automatic� identification, shipments could be received simply by driving a lift truck past an antenna.
Taking the next step in RFID applications, a large US sports equipment manufacturer has recently started embedding an RFID label inside snowboards. The RFID label will now be laminated directly inside the snowboard and will be used to track the product through the manufacturing process, and distribution channel and then be used to ensure product authenticity at the retail level. With product counterfeiting operations shaving billions of dollars of profits from legitimate companies, many companies are fighting back, using RFID as the preferred arsenal of choice. The product can also permanently store warranty and customer information for the life of the product. As a side benefit, the RFID system will operate as a theft deterrent EAS system, sounding buzzers if someone attempts to shoplift the snowboard.
In a distribution environment, as more and more products are similarly tagged, accurate inventories could be generated simply by driving or walking down the warehouse aisle with an RFID reader.
RFID Checklist � Find the best solution
The following is an RFID application criteria checklist that will allow you to determine the best RFID solution for your application:
� Frequency � 13.56Mhz has become the standardized frequency for North America and Europe, since it uses harmless, FCC and IATA approved low-frequency waves. The microwave frequency of 900 GHz and higher has severe operating restrictions in Europe, thus greatly reducing the reading ranges. However, other frequencies are available and, if they are to be used only internally, may provide better performance.
� Read-only or read/write � For asset tracking alone, read-only may offer reliable, highly tamper-resistant identification. For other applications, read/write systems that can record a tote�s contents or path through a facility may be required.
� Memory � How much data do you want to write to the tag? Typically 48 bytes is ample for a time/date stamp, including location and product ID number. Assembly applications generally need more memory (8K to 32K bytes) since they write the complete production history on the tag.
� Active vs. passive systems � For supply chain RFID solutions, the popular choice is passive. Since the tags can be in label form, they do not require batteries and are less costly than the active, higher memory tags.
� Mounting � Generally, RFID ranges are greatly affected if the tag, label or PCB is mounted directly to metal. However, there are solutions to deal with this concern. A well-experienced RFID company can provide solutions to tag on metal applications.
� Disposable versus reusable tags � Will the tag/label operate in an open-loop system? If so, this would be a disposable application since the RFID tag will not be recycled within the facility. If the tag is mounted onto a transport carrier or returnable container and will be recycled within the process, this will be a closed-loop system and perhaps a PCB or encapsulated tag is the best solution.
� Line speeds � This point is often overlooked but is critical to any supply chain or conveyor-based application. Different antennas and tags provide different data transfer speeds (e.g. active systems can transfer data at the rapid rate of 3,000 bytes per second).
The following two points are additional considerations for selecting vendors and implementing systems.
� PLCs or PC � So you picked out the RFID system, have all the equipment in front of you and now you realize, �How is my RFID system going to interface to my host network?� It is important to work with a manufacturer or integrator that has experience in PLCs and PC interfacing. Look for a network interface module that interfaces to the majority of the worlds industrial networks (e.g. Allen-Bradley, Modicon, etc.). The RFID company should be more than just selling RFID tags, but should be knowledgeable enough to provide you a complete system interface solution. Even if interfacing to a simple PC, the RFID company should be able to provide you with software support (should you need it).
� Bus networks � Industrial applications often operate with bus networks (e.g. DeviceNet, Profibus, etc.), and it is imperative that the RFID company provide you with a quick plug-and-play interface device to link the RFID system to your bus networks.
RFID systems can play a significant role in warehouse and distribution environments today by providing fast, accurate and automatic identification, tracking and data capture. The next generation of RFID will extend these benefits well outside the walls of the facility, allowing information to travel with items from suppliers all the way through the supply chain to customers.
Stephen Crocker is the global MarCom manager for Escort Memory Systems (EMS). He can be contacted by phone at 831-438-7000 or e-mail scrocker@ems-rfid.com. You can visit EMS on the Web at www.ems-rfid.com.
