We are using passive RFID tags in a warehouse to identify and track shipments. Each shipment comprises a carton containing our passive tag, along with any items from third-party companies. In some cases, the items contain passive tags attached by those companies. This means our reader will pick up both our tags and the third-party tags. What logic can we use to ignore the third-party tags? We have considered using brute-force mechanisms to avoid those tags, like checking the serial number range, and we would like to find out whether we can identify the tags' owner at the tag level—say, using any memory area of the tag other than the EPC memory, or maybe passwords.
If you and your suppliers are employing serialized Global Trade Identification Numbers (GTINs), then the first few numbers of the Electronic Product Code (EPC) after the header will identify the third-party companies. This is the EPC Manager, and it take up eight to 35 bits of memory. Each GS1 member organization receives a unique EPC Manager number, so you would not need to read the entire serial number to make this determination. You could set up your reader software to pass along data to the back-end system only if a tag began with your EPC Manager number.
If you are not using serialized GTINs for the EPC, you could write a number in the user memory to identify your tags, and then have your readers pass on data only if there were a 1, for example, in user memory bank one. Of course, if your suppliers were to write a 1 in that user memory bank for some reason, then your readers would still think this was your tag and would pass along the information to your back-end system. For that reason, the first option above is better.
—Mark Roberti, Founder and Editor, RFID Journal
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