Mid-Range Technologies

- Fast & Accurate -

EPC was created at MIT by the Auto-ID Center as a solution to the limitations of UPC, or bar codes.

With this in mind it should come as no suprise that this technology is designed to allow reading a huge number of tags at the time, with great speed. The technlogy is also unique in several ways, situated between the vehicle focused long range technologies and the access control focused near touch technologies, EPC blends the two together and adds many interesting capabilities.

EPC also allows each item to be identified individually, instead of simply as part of a group allowing attributes such as colour, cut and any other feature to be tracked accurately within inventory, allowing you to make smarter business decisions.

EPC RFID Gen 2 - What is it?

EPC stands for Electronic Product Code, the GS1 replacement standard for the older UPC (Universal Product Code) barcodes. UPC first started in 1963 and has been pushed past it's limitations in terms of scaleability and feature set. EPC resolves these modern demands with careful through given to future expandability and demand.

EPCglobal is the trade organization leading development of global industry standards and adoption of EPC RFID for today's information hungry trading networks. EPCglobal organizations are in every country that is working towards making EPC the end to end supply chain standard.

Gen 2 or EPCglobal Class 1 Generation 2 defines the physical and logical requirements for a passive-backscatter system, where the Interrogator (RFID Gen 2 Reader) Talks First (ITF), somewhere between 860 MHz - 960 MHz frequency range depending on the country. Prior EPC tag standards were known as Class 0 and Class 1 of which neither was widely deployed. EPC Class 1 Gen 2 represents a major step in standardization, performance and quality.

As with most technologies, the lengthy name Electronic Product Code Class 1 Generation 2, has been shortened into a number of trade names including Gen 2, EPC Gen 2, and EPC C1G2.

It's important to note that while the EPC standard operates across the entire 860 MHz ~ 960 MHz frequency range, there are a number of Organizations and Governing bodies that regulate the frequency and transmission power in the different countries. As such no country can legally operate over the entire band. The two most common frequencies of operation are 860 MHz ~ 868 MHz which is recognized through most of Europe, and 902 MHz ~ 928 MHz which is used in North America and various other countries.

EPC also uses FHSS (Frequency Hopping Spread Spectrum), a technique which rapidly switches the carrier among many frequency channels during the radio signal transmission, to get the best possible read from the tag. Using FHSS the reader can get several different reads from the tag and then compare the results to determine if the read was successful or not.

Gen 2 Readers

Gen 2 readers come in two main flavors - EPC Gen 2 Certified and Gen 2. Both types of readers are capable of reading and writing to Gen 2 tags. In some cases the readers may also read and write to the earlier Class 0 and Class 1 tags (ISO 18000 - 6B).

EPC Gen 2 Certified readers use the same O/S (operating system), low level reader command set (LLRP), and are totally interchangeable with other manufacturers without any changes. Simple swap in and swap out. The differences between manufacturers relate to enhanced functionalities not in the Gen 2 standard such as enhanced read and write sensitivities or tag direction sensing.

EPC Gen 2 Certified readers have 3 reader modes (single, multiple and dense) which are required by the Gen 2 standard for using the reader in different environmental situations. The EPC Gen 2 Certified readers are firmware upgradeable to ensure full compliance with all of the still unfinalized EPCglobal specifications. Gen 2 Certified readers also have 2 read modes; fast which can read over 1,600 tags per second, and slow which reads less than 600 tags per second. The read speed is set automatically and depends entirely on the actual read conditions. The high speed read is called FM0 Baseband and reads tags at a speed of  40 ~ 640 Kbits/s and the low speed read is called Miller and operates at 5 ~ 320 Kbits/s. Miller low speed is automatic when the reader senses a tag but can not read it using FM0 Baseband.

Gen 2 readers are capable of reading all Gen 2 tags, but are not interchangeable between manufacturers and may not even be interchangeable between models by the same manufacturer. Other differences are that they usually do not have the read rate of the Gen 2 Certified readers, their power ratings may be less. Their pricing reflects these differences, usually coming in 30% to 50% less than a Gen 2 Certified reader.

EPC Tag Classes

EPC tag capabilties are broken down into classes and each class has specific capabilties and is backward compatible to the preceeding class.  Each higher class maintains the previous capabilities and characteristics and adds new capabilities.

EPC Class 0 Tags

EPC Class 0 is Generation 1 also called Gen 1.  Generation 1 are tags that you can write once and read many times (WORM). This class of tag is factory programmable and not field programmable.

EPC Class 1 Tags

EPC Class 1 is Generation 1 and Generation 2, also called Gen 1 and Gen 2.  Class 1 tags are WORM tags but can be read by readers from other companies.  EPC Class 1 Generation 2 (EPC Gen 2 or just Gen 2) are WMRM (Write Many Read Many) tags that have a minimum memory of 256 bits of which 96 bits is for the EPC number. Gen 2 tags have better tag identification, which allows the reader to eliminate duplicate reads during multiple tag scans.  Gen 2 tags can also be read by all Gen 2 readers due to vendor neutral design specifications. Gen 2 tags read up to 10 times faster than Gen 1 and provide extremely high read rates on tags - literally 100%.  In addition the actual I/C (Integrated Circuit - that can contain over 50,000 transisters) is 2 to 3 times smaller than the earlier Gen 1!

EPC Class 1 tags also have a function that can render the tag permanently non-responsive.  Options to Class 1 tags are decommissioning and recommissioning of the tag, passwords protected access control and optional usery memory.

EPC Class 1 Gen 2 Tags

EPC Gen 2 tags come in several different flavours - EPCglobal - meaning that the tag can be read at any frequency between 860 MHz and 960 MHz, EPC Gen 2 860 MHz. ~ 868 MHz, also known as European Gen 2 and Gen 2 902 MHz ~ 928 MHz known as the North American Gen 2.  An excellent flavour of the EPCglobal tag is an EPC World Tag - this world tag has a maximum read deviation of 1.5 dBi over the entire read spectrum from 860 ~ 960 MHz making it perfect for world/global solutions.

Effectively you can use a single tag throughout the world that positively identifies the tagged item directly back to the source, hence end to end supply chain management and visibility.

Gen 2 tags come in a very wide variety of types, shapes and sizes that are usually designed for a specific application.

Generic longevity specifications for Gen 2 IC's are 40 - 50 year data retention and 100,000 write cycles

A pallet tag can have a read distance of over 10 meters when attached to the cardboard or wooden case, but when attached to a metal shelving support the pallet tag has a read distance of zero to 0.5 meters.

For attaching to metal objects a metal mount tag should be used and depending on the type of metal and the type of metal mount tag you can achieve a read range of 10 meters or more when attached to metal. Each metal object does provide a different metal mount tag requirement and depending on the overall environment the reader frequency may need to be changed in order to achive the best read rate and distance.

Tags can also be orientation sensitive due to the inlays used in making the final tag.  Some tags can only be read in a vertical or horizontal postion, some tags will only read on the edge, and then some tags can be read regardless of the orientation.  Just because your friend uses XYZ tag does not mean that this is the best tag for your application.

Each application needs to consider the read and write requirements and then look at the tag that meets those requirements.  Temperature, read distance, working environment, storage environment, read angles, and more need consideration so you can then determine what Tag IC and antenna combination will work the best.

Using the right tag for your application can make the difference between a successful implementation or a failure!

All Gen 2 tags contain the same basic memory features:

96 bit EPC number support (can and is used for many other purposes as has read write capabilities)

32 - 64 bit tag identifier (TID) - identifies the manufacturer of the tag and also has read write capabilities

32 bit kill password to permanently disable the tag

32 bit access password to lock the read write characteristics of the tag and also set the tag for disabling

Some tags include user memory of up to 2048 bits or more depending on the tag.

EPC Class 2 tags are enhanced Gen 2 Class 1 tags.  They contain all of the Class 1 features plus an entended TAG ID (TID), extended user memory, authenticated access control and additional features that will be defined in the Class 2 specification not yet completed.

EPC Class 3

EPC Class 3 tags have not yet been fully defined, but are battery-assisted passive tags somtimes called semi-passive tags in UHF Gen 2.  Anticipated features are a power source to supply power to the tag and/or its sensors and or sensors with optional data logging capabilities.

These new Class 3 tags will still communicate passively, meaning they will require a reader/interrogator to initiate communications and send information to the readder using either backscatter or load -modulation techniques (For a better understanding of RFID communications we recommend you take our 6 free lesson RFID course)

EPC Class 4

EPC Class 4 is active tag technology.  The UHF tag will contain a battery and can initiate communications with a reader or with another tag.  Class 4 active tags will not interfere with the communications protocls of Class 1, 2 or 3 tags. Class 4 tags with contain an EPC identifier, and extended Tag ID, authenticated access control, a power source, communicaitons via autonomous transmitter, have optional user memory and optional sensors with or without data logging capabilities.  This Class 4 tag is still in the early definition stage.

We hope this information has assisted you in the understanding of Gen 2 and how it can relate to your needs.