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YeinCM-Qva February 2016

Why is my RFID reader reading an unexistant RFID tag code?

Our team is developing a software application to read RFID tags using an MC3190Z RFID Handheld Reader. We are using EMDK for .Net v2.9 and Visual Studio 2008, testing and deploying directly to the device.

This reader is showing an unknown RFID tag code in every single reading process, even if there are no tags around the antenna range. This is the EPC code always present: A7423000AD47240312719F756E0000F0

This process repeats either using our application, or using any standard applications such as RFID RapidRead/RFID Demo/Tag Locator (downloaded from Motorola website).

We though it could be related with some sort of stored or default information stuck in our reader, but we were using the right mechanism to use the reader capabilities described in the documentation. We also did a cold and hard reset to our device trying to fix the problem but nothing worked.

Any help or comments around this will be very welcome.


oli-ver February 2016

I think this is a quite normal behavior. We use RFID too and the reader we use does send a default value, if there is nothing to read, too. I do not recall what value, because we have a software that generates events in form of messages if the value changes for the application using the data of the RFID reader.

Is it necessary for you to change this default value?

Shain Armstrong February 2016

Interestingly, the issue may be that you are, in fact, reading an existing RFID tag.

I'm not sure if this is still the case but, in the past, the strap that shipped with the MC3190-Z RFID device contained a UHF RFID tag embedded within it. When we first received our handheld, we attached the strap and started reading RFID tags; however, much like you state above, we kept reading a single tag over and over again. No matter how we isolated the MC3190-Z device, we ALWAYS read the same RFID tag.

As it turned out, we were simply reading the UHF RFID tag that came embedded into the strap. Once we removed the strap, everything was fine. If you are using the strap, remove it/isolate it, and see if that helps.

Altneratively, you can set your program to filter out that particular tag ID, but you shouldn't have to do that.

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Asked in February 2016
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