Sharing Tag Space

By Ken Traub

Gen2v2 lets supply-chain partners manage their own information.


A passive EPC Gen 2 ultrahigh-frequency RFID tag has user memory that can function as a miniature database, accumulating useful information about the object to which the tag is affixed. Consider, for example, an RFID-tagged aircraft part. The part manufacturer can write the date of manufacture on the tag. The airframe manufacturer can store information regarding how the part was installed and inspected. And over time, the airline can add specifics about maintenance and repair operations.

Some Gen 2 tags have large user memories—up to 64 kilobytes—and can accommodate all this data. But complications arise when supply-chain partners want to put their own data into the same memory. For the data to coexist, all parties’ software must coordinate use of this shared memory. This is difficult because the part manufacturer doesn’t know which airline will use the part, and supply-chain partners likely use different software.

Gen2v2 solves this problem by allowing the user memory to be divided into “files” (see GS1 Ratifies EPC Gen2v2, Adds Security Features, More Memory). The new protocol gives tag manufacturers the freedom to implement the file feature in different ways. Some manufacturers hard-code tags with specific file settings. Others let the first end user configure the amount of memory needed for its file, using Gen2v2 commands issued by an RFID reader controlled by a software application; the next end user can then allocate its file from the remaining memory, and so on.

Each file can be accessed as though it were a separate memory bank. So now the part manufacturer can have one file, the airframe manufacturer another and the airline a third, and each company’s software can read and write its own file without disturbing the content of the other files.

Gen2v2 also allows each file to have its own security settings, with separate passwords to control access. So the part manufacturer can set its file so all parties can read the expiration date but only the part manufacturer can write or alter that data. Similarly, the airframe manufacturer and the airline can set their files with different permissions, based on need.

This means supply-chain partners do not have to worry about their data conflicting with any data previously written to the part. Each partner can use its own software to read or write a file, without any coordination with the others.

To take advantage of this feature, end users must have RFID readers equipped with upgraded firmware capable of issuing the Gen2v2 “file open” command, to select the file to use when interrogating the tag. The middleware or other software controlling the reader also may require upgrading. In addition, the software should be configured to store a Gen2v2 “file ID” value with each file, so each party can identify its own file.

Ken Traub is the founder of Ken Traub Consulting, a Mass.-based firm providing services to com­panies that rely on advanced software technology to run their businesses. Send your software questions to