Tag Reads - Filters
RFID filtering for accurate data

Although the functionality of RFID and barcoding overlap in certain applications, RFID reading operates differently than other technologies.  Barcode scanning operates on the principle of scanning at a critical point – one barcode at a time. Barcode scanning operates on the principle of a scanning at a critical point – one barcode at a time.  In fact, most applications will have a prompt that must be filled by scanning a barcode.  Or the prompt could be manually entered by typing in data.  For example, in an inventory picking application, an employee would be asked to "scan" the part number, then once complete, scan or hand enter the quantity.

In contrast, RFID technology executes that same function in a different manner. One of its biggest benefits is the ability to read many RFID tags at one time.  So when the employee pulls the read trigger or when a pallet of product enters a read zone, many RFID tags are read at once, including duplicate tags being read from more than one antenna. The ability to filter RFID tags allows the application to run smoothly without error.  A barcode application designed to read one barcode would be overloaded with data causing the application to fail.

Filtering

RFID tags must be filtered at the time of reading to isolate the tag reads desired.  Tags must be compiled to a list within the reader and sent to a server or processor.  The server must then review the tag list, identify the duplicates, and apply business logic to the application. The filtering process, correctly reading RFID tags, is what adds the most value to a business and adds the most complexity to an RFID system.

An example of business logic can be displayed in the pallet read process.  If a pallet containing 60 case RFID tags and 1 pallet RFID tag identifying the products in our inventory control system moves into the read zone, the reader will start the process capturing tag reads. Of those reads, we may have seen all 60 case tags and the single pallet tag, but we also got the duplicates as the pallet moved through the zone.  When this happens, users may get a  reader that has received a total of 525 tag reads.  These reads now need to be filtered to eliminate duplication and ensure the application runs correctly.

The reads are gathered into a list in the reader and the duplicates within that list are removed.  This data is in a hexadecimal format and must be converted to ASCII to be held in a database for human use.  The reader sends the list in a file format up to the server or filtering processor to have the business logic applied.  The server’s software must then review the tag list and determine if any of the tags are "pallet" type tags.  These are typically encoded with a different header in the hex value so that it is easily isolated within the server.

If our desire at this point is to read pallet tags and count them to verify shipment counts, then the server would review the pallet tag against a list of valid pallet tags for the shipment.  If this pallet tag is on the valid list, then the shipment count is incremented by one and the server signals to the reader to turn on the green stack light to signal the operator that all is OK.  In this part of the process, the system will also feed a user screen to display the correct count and reduce the inventory while adding the contents to the shipment manifest.

Without the server filtering the tag list, we could not get the value from the RFID system.  Instant, accurate counting with operator validation and data table updating happens automatically without users stopping to scan or manually updating multiple screens or databases.