In the world of radio frequency identification, “generation” refers to the version of the standard employed. EPC Gen 2 was the second version of the air-interface protocol standard for passive ultrahigh-frequency (UHF) tags developed by GS1/EPCglobal. The EPC Gen 2 standard is incompatible with Gen 1, and has many additional features, so Gen 2 was a way of differentiating hardware based on the two different standards.
The term “class” was used by the original Auto-ID Center to differentiate among the capabilities of different types of tags. Here is a breakdown of the classes as originally proposed.
• Class 1: a simple, passive, read-only backscatter tag with one-time, field-programmable non-volatile memory
• Class 2: a passive backscatter tag with up to 65 kilobytes of read-write memory
• Class 3: a semi-passive backscatter tag with up to 65 kilobytes of read memory (essentially, a Class 2 tag with a built-in battery to support increased read range)
• Class 4: an active tag that uses a built-in battery to run the microchip’s circuitry, and to power a transmitter that broadcasts a signal to an interrogator
• Class 5: an active RFID tag that can communicate with other Class 5 tags and/or other devices (essentially, tags that can form ad hoc mesh networks)
—Mark Roberti, Founder and Editor, RFID Journal
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