Once the decision about adopting RFID to the company’s operations has been made, a number of issues need to be considered. This article discusses the issues related to tags and the tag writing; tag features and the communication between the tag and the reader.
Co-authors: Toni Heijari, Turo Rantanen & Mikko
The tag and the reader
The picture below shows a basic model about how a tag and a
reader communicate with each other. In case of passive UHF RFID,
the basic idea is that the tag receives all the energy it needs
from the radio frequency wave that the reader is sending.
Therefore, a passive tag does not need a power source of its
To understand how the demo and tag writing actually work, you
need to understand how the tag itself works.
EPC Global Class-1 Gen-2 UHF RFID tags consist of 4 memory areas,
which are called banks. These banks are numbered from 0 to 3. The
banks and their purpose are described below.
Bank 3 is the user memory, which usually is
empty before the tag is written. Apparently, all the tag types have
the 3rd bank, but the bank does not necessarily have a memory. Bank
3 can be used for various purposes. A retailer can use it to add
product information such as the type of the product, for instance
the type of the product (trousers), color (black) and size (36).
When a customer is asking for black trousers in size 36, the
retailer can use a tag locating application with a mobile RFID
reader and thus search all the available options from all
collections and brands in the store with the requested parameters.
When the information has been written to the tag itself, the
RFID readers can operate without connecting to the business
information system. Therefore, the search can be carried out
rapidly. EPC can be created in a way that it already includes
information about the product, meaning that in some products the
retailer can see the collection, type of garment, color and size of
an item from the EPC. With this kind of an EPC it is possible to
search based on some parts of code (for example 02 for trousers, 01
for black, and 03 for size 36) and search only for tags including
those parts in the EPC. Here the reader asks the tags filling the
condition to respond for calling. By doing this only the tags that
have that part of the EPC code are replying. In this way the search
can be done more rapidly compared to not using filtering at first
place. It is also possible that the tag can send two different
kinds of information. These so-called near-field memory tags tell
their EPC as answer when read from a long distance, but in a short
distance change the memory area and tell some other information
about the tag. There is also a tag which contains areas for public
and private information. Here the user can set the area used.
The content of the tag itself varies between different users.
Depending on the operation that a company runs and depending on the
need to recognize tags, the content of the tag varies. Retailers
who distribute products from several suppliers tend to look for the
supplier to create the tag similarly to how they operate with
barcode these days. On the other hand especially vertical retailers
looking to replace barcodes with RFID tags may initially insert the
numeral series of the barcode which will form a part of the EPC in
blog post about more practical tips to tag writing!