Ah, I see. That's probably all in software, so you can define any kind of access control based on the card readings in your own particular use case. Just got to be careful, because these cards are scanned and clones pretty easily (at east in this case, only reading the serial number). Might combine with an NFC enabled app, as this reader seems to be able to use NFC too, and there you have more degrees of freedom to set up your security system.

What kind of generality and security features you have in mind? Curious how others would extend this very simple proof of concept.

Thanks! Planning to make it into a cleaner setup and maybe into some kind of kit to make it reusable...