NExT Gym Card doesn’t work

I’ve just got my NExT registered to be my keycard to my gym. It scans correctly, and it’s registered in the system seemingly correctly. But it doesn’t unlock the door or gates.

I’m unsure if there’s some encryption that my chip is missing, but it’d surprise me as the keycard is just a cheap mass produced rfid card.

Any suggestions to fix it. I have full access to the gym’s computer system, if needed

If you compare an actual card and your NeXT with NFC Tools for instance , do you see any difference?


I’d say step one is to test the door reader with the RDC and see if it’s possibly dual frequency.

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I have an iPhone so I can only read the high frequency NFC, where the keycard is rfid. I can whip up an Arduino reader if that can help me

RDC? What’s that? The door reader reads my chip, and gives off a beep

Ahh the RDC is

You should have gotten one in your NExT kit.

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The purpose of using the RDC is to determine if the reader is multi-frequency. If so, the wrong chip inside your NExT might be getting read by the reader and causing it to beep, but the wrong chip ID is being reported back to the door controller.


Good idea to make RDC an automatic keyword with the link to the page :wink:


I didn’t get anything other than the chip and inserted. But I bought it from a German store so maybe they just didn’t sell that part.

I have a high frequency NFC tag lying around. Could I try that to see if it reads that? Would that be similar?

@Pilgrimsmaster are you able to do this?

Of course the resident AI is able to do it!

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yay RDC now links :slight_smile:


Diagnostic Card
Already was, but who has time to type out the full words :wink:



Not @amal the boss! :sweat_smile:


Hi again. I just tested with another high frequency chip (still don’t have the card) and that is exactly what is happening. The card coder at the gym only reads the low frequency, but the entrance readers will only read the high frequency if offered both.

Is there anything to do without tampering too much with the scanners themselves?

I have this exact issue with my gym card. I don’t think there is a fix besides asking them to disable the HF side of the reader.

As far as I know that isn’t possible. Unless it’s done physically on the reader itself. Do you know how that works?

You need the ability to power cycle the reader and any password if present.