GS1 System

EPC Gen2

EPC Gen2 is short for EPCglobal UHF Class 1 Generation 2. Commonly known as the "Gen 2" standard, this standard defines the physical and logical requirements for a passive-backscatter, Interrogator-talks-first (ITF), radio-frequency identification (RFID) system operating in the 860 MHz - 960 MHz frequency range. The system comprises Interrogators (also known as Readers), and Tags (also known as Labels).

The UHF Class-1 Generation-2 air interface protocol V1.2.0 extends the item-level tagging capabilities of UHF Gen 2. In this protocol, 3 optional features have been added. An indicator is now available to show when there is formatted data in user memory. Addition of permalocking on a block level in user memory now protects contents that have already been written. Recommissioning of a tag after POS operations is now available. The recommissioned action is indicated through the inclusion of extended protocol control bits.

In 2004 the Hardware Action Group created a new protocol, the Class 1 Generation 2 interface, which addressed a number of problems that had been experienced with Class 0 and Class 1 tags. The EPC Gen2 standard was approved in December 2004. This was approved after a contention from Intermec that the standard may infringe a number of their RFID-related patents. It was decided that the standard itself does not infringe their patents, making the standard royalty free. The EPC Gen2 standard was adopted with minor modifications as ISO 18000-6C in 2006.

EPC / RFID Tags

EPC/RFID tags use Radio Frequency Identification (RFID) technology to encode GS1 ID Keys in the GS1 Electronic Product Code (EPC). They also enable the EPCIS GS1 Communication Standard.

RFID works via a microchip, which stores the relevant data (including the EPC) and reflects the data to the reader antenna by means of electromagnetic waves. Since these waves can pass through solid materials, the chips may be shielded by adhesive film or integrated directly inside the package or product.

EPC/RFID tags encoding the GS1 EPC can offer a significant time saving advantage over other GS1 Data Carriers. The reader and transponder do not need to be in each other’s line of sight and the transmission/reading process is ultra-rapid, which means that this Data Carrier has bulk data capture capabilities – an entire supermarket caddy could be “scanned” in the blink of an eye without needing to manually pass each item in front of a scanner.

There are two types of RFID tags - active tags and passive tag. A Passive tag is Tag whose microchip is powered by the RF field created by the Reader. An active tag is an RFID device which has the ability of producing its own radio signal not derived from an external radio signal. To generate a radio signal active tags must employ some source of power. Traditionally this has been accomplished by integrated batteries, although designs exist for such devices that employ solar power or harvest ambient energy from the surrounding environment.

There are five different classes of RFID Tags. These are

Class 1 – Read only (the RFID tag can only be read by a reader)
Class 2 – Read, write once (information can be written into the tag once)
Class 3 – Class 2 capabilities plus a power source to provide increased range or advanced functionality
Class 4 – Class 3 capabilities plus active communication and ability to communicate with other tags
Class 5 – Class 4 capabilities plus the ability to communicate with passive tags as well.

Radio Frequency Identification (RFID)

Radio Frequency Identification is a technology which enables data to be transmitted, via radio waves, across an air interface, in compliance with a set of locally or globally agreed laws and standards. It is an established data-carrying technology, used throughout industry in various formats for decades but it is not the ‘solution to all problems‘. It is merely a 'tool’ to enhance accuracy, efficiency and information provision, within or between organizations.

The data contained is often merely a unique ID relating to the item/object and is stored on a tag which is attached to the item/object. A tag on entering a radio field operating at the same frequency, is activated by the energy of the radio waves emitted from the reader creating the field. On activation, the RFID tag sends data relating to the item, stored in its memory, back to reader via radio waves.

The RFID tag enables the chip to receive and respond to radio-frequency queries from an RFID transceiver. There are three types of RFID tags, namely

Active Tags are equipped with a battery that can be used as a partial or complete source of power for the tag's circuitry and antenna. They can initiate activity or response. They can be read at distances of one hundred feet or more. They may have other sensors that can use electricity for power. They can be turned off.
Passive RFID tags rely entirely on the reader as their power source. They are only capable to respond. These tags are read at short range (up to six meters away).They have lower production costs and thus less expensive.
Semi-passive tags operate similarly to passive RFID tags. However, they contain a battery that enables longer reading distance and also enables the tag to operate independently of the reader. It is important to understand that the communication in semi-passive tags is still completely passive; no power is transmitted – the tag simply reflects back some of the power emitted by the RFID reader.

There are three storage types of RFID tags that affect its price, namely: read-write, read-only and WORM (write once, read many). A read-write tag's data can be added to or overwritten. Read-only tags cannot be added to or overwritten -- they contain only the data that is stored in them when they were made. WORM tags can have additional data (like another serial number) added once, but they cannot be overwritten.