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Pepperl+Fuchs Blog

ISO Standard RFID Tags Decoded

Posted by Tim Cicerchi on Thu, Mar 21, 2013

RFID technology adheres to the ISO/IEC 15693 standard

The Pepperl+Fuchs high-frequency RFID system is open and easy to use.  When I say “open” I mean that it adheres to the ISO/IEC 15693 standard.  We can read anyone’s RFID tags made to this standard and anyone can read our RFID tags.  The openness of the system has allowed multiple manufacturers to produce chips, electronics that are in the tag, making the overall tag price very cost competitive.  Even though all of these chips adhere to the same standard, slight differences in functionality and features mean it is important for our RFID controllers to know which chip will be read before we try and read it.  This one configuration parameter, easily programmed into our controllers, is called the “tag type.”

The tag type is a two-digit identifier from 00 to 99 that represents a specific RFID chip type.  If you buy an RFID tag from us, for example IQC21, that tag type is 21.  The tag type always follows the IQC prefix in the model number.  You don’t really need to know what chip was used to make the IQC21 tag.  You just enter the 21 into the read head parameter field and you are done.

There is an alternative to entering this tag type as a parameter in the controller.  You can use the default tag type of 20.  The type 20 doesn’t represent a chip at all but refers to all ISO standard tags.  The read head will attempt to decode the tag type before the required read or write operation is initiated.

So this is how it works.  Let’s say you want to write 8 bytes to a tag and you are not exactly sure what type of chip it is.  Leave the tag type at the default and perform the write operation.  What happens is the fixcode or UID on the tag is read first.  This is an 8-byte unique identifier.  The manufacturer and chip type can be decoded from this number.  Once the chip is known, the write of 8 bytes is performed automatically.  Reading the code first adds about 20 ms to the overall write time because the UID had to be read first, but everything was done under-the-hood without user knowledge.

The UID is just the unique read only identifier that is on the tag.  This number is unique no matter where you buy the chip.  This is possible because the number is composed of a unique manufacturer number and a unique chip number.  Also, each manufacturer is required to only program tags with unique numbers.  No number can be used twice.  The result is that duplicate numbers on ISO 15693 tags are never produced.  Here is a breakdown on how each UID is coded.

RFID tag unique read only identifierYou may ask why we care about the RFID tag type because all high-frequency tags adhere to ISO/IEC 15693-3 standard.  This is true, but there are mandatory and optional features in that standard, and we believe that it is important for an RFID system to operate as fast as possible.  For example, Texas Instruments makes a chip they call the HF-I Plus and another one they call the HF-I Standard.  The Standard chip requires that the reader access one block of data at a time.  The Plus chip has a read-multiblock feature so the reader can read all the data off the tag all in one large block.  You could always just read one block at a time off of either tag, but if you need a lot of data this wouldn’t be very efficient.  

Another reason to know the tag type is because of the block size.  Certain tags, like the 2 k Fujitsu chip, allow reading of only 8-byte blocks.  If the tag type is set to 33, which is the Fujitsu tag type, then all commands with block sizes that are not in multiples of 8 bytes are rejected before any communication is attempted on the read head.  This makes it easier to determine where the problem was when the failed response comes back.

Here is a list of many of the tag types and their associated chip types that are supported by Pepperl+Fuchs.

RFID Tags and Chip Types
All Pepperl+Fuchs ISO standard systems are open.  This means that no encryption has been enabled by default.  This allows the user to buy a low-cost “slap-and-ship” type RFID tag and read it with one of our systems.  Use the tag type chart above to configure the RFID system for any tag purchased from Pepperl+Fuchs or on the open market.

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Topics: RFID

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