Gen 2 RFID tags are comprised of an antenna and a chip (more accurately called an integrated circuit, or IC). The ICs for Gen 2 tags contain four types of memory:
* Reserved memory
* EPC memory
* TID memory
* User memory
When starting your application and selecting a tag, in order to know about how much memory is on each tag’s IC, you can check the specifications page on each tag’s data sheet. To learn the properties of each memory bank, we have outlined them below:
This memory bank stores the kill password and the access password (each are 32 bits). The kill password permanently disables the tag (very rarely used), and the access password is set to lock and unlock the tag’s write capabilities. This memory bank is only writable if you want to specify a certain password. Most users do not use this memory area unless their applications contain sensitive data. It cannot store information besides the two codes.
This memory bank stores the EPC code, or the Electronic Product Code. It has a minimum of 96 bits of writable memory. The EPC memory is what is typically used in most applications if they only need 96 bits of memory. There are some tags that have the capability of allocating more bits to the EPC memory from the user memory. EPC memory is your first writable memory bank.
This memory is used only to store the unique tag ID number by the manufacturer when the IC is manufactured. Typically, this memory portion cannot be changed.
If the user needs more memory than the EPC section has available, certain ICs have extended user memory which can store more information. When it comes to user memory, there is no standard in how many bits of memory are writable on each tag. Typically, the extended memory is no more than 512 bits, but there are some high memory tags with up to 4K or 8K bytes of memory. This is the second writable memory bank for Gen 2 ICs.