Also, what companies’ chips utilize this function?
“Margin Read” is an EPC Gen 2-compliant custom command that allows a reader to explicitly verify that the non-volatile memory (NVM) in a tag’s chip has been written correctly. When data is written to a passive UHF Gen 2 transponder, a charge is built up in the memory cell. Once the charge reaches the appropriate level and the information has been successfully written to the memory cell, the tag sends back a signal indicating that the write process is complete.
Sometimes, when people are encoding tags in the field, they do not wait for this confirmation from the tag, and they instead read the data from memory. The problem is that the tag might return the right data, but if not enough charge was stored up, the information might not remain in memory, so Margin Read is a way of ensuring the write operation was properly completed. Margin Read is a feature of Impinj’s Monza 6 chip, though not all readers support this feature.
—Mark Roberti, Founder and Editor, RFID Journal
Who Makes Read-Write Implantable Passive Tags? »