Some months ago I bought this 125kHz RFID Reader / Writer from eBay.

enter image description here

I was wondering how can I actually read or write an RFID Tag with it. So I attached it by usb to my computer (running Linux) and saw just this:

[786026.932028] usb 3-1: new full-speed USB device number 3 using uhci_hcd
[786027.092100] usb 3-1: New USB device found, idVendor=10c4, idProduct=ea60
[786027.092107] usb 3-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[786027.092111] usb 3-1: Product: CP2102 USB to UART Bridge Controller
[786027.092115] usb 3-1: Manufacturer: Silicon Labs
[786027.092122] usb 3-1: SerialNumber: 0001
[786027.262224] usbcore: registered new interface driver usbserial
[786027.262243] usbcore: registered new interface driver usbserial_generic
[786027.262257] usbserial: USB Serial support registered for generic
[786027.267525] usbcore: registered new interface driver cp210x
[786027.267546] usbserial: USB Serial support registered for cp210x
[786027.267583] cp210x 3-1:1.0: cp210x converter detected
[786027.376029] usb 3-1: reset full-speed USB device number 3 using uhci_hcd
[786027.522286] usb 3-1: cp210x converter now attached to ttyUSB0

I tried to print characters to serial port echo "blah" > /dev/ttyS0 but nothing is answered by the RFID reader ( with cat /dev/ttyS0 ).

Since it's a chinese RFID Reader not much infos could be retrieved from internet. No usage specifics. Nothing.

I tried to search over internet the model name: HL-208 but I haven't found anything that could help me reading / writing my RFID tags.

I also looked for that cp210x and undercovered that is actually an USB to UART Bridge.

"Bonus" Question: How can I actually determinate which type of RFID tags are these? Is there anything I can do, except trying it with every single RFID Reader specific to the model, to determine which frequency and type they are?

  • \$\begingroup\$ What happens if you try cat /dev/ttyUSB0? \$\endgroup\$ – PeterJ Dec 31 '13 at 8:36
  • \$\begingroup\$ Actually nothing. The file doesn't exist \$\endgroup\$ – Denys Vitali Jan 1 '14 at 12:08
  • \$\begingroup\$ Interesting it looks like it got enumerated as ttyUSB0. One other thing that might be worth trying is listing the contents of /dev recursively without it attached and compare against anything new that appears once it's been attached. \$\endgroup\$ – PeterJ Jan 1 '14 at 12:17
  • \$\begingroup\$ Damn, my fault! Actually it exists but it doesn't give any output. \$\endgroup\$ – Denys Vitali Jan 1 '14 at 12:23
  • \$\begingroup\$ Could be a tricky one then, the 89C is a general purpose microcontroller so they might have used just about any protocol. Did it come with Windows software? From memory I think the free Microsoft PortMon program works with USB to serial adapters and you might be able to see what it sends / receives. \$\endgroup\$ – PeterJ Jan 1 '14 at 12:41

Since the reader actually works on the serial interface you will probably need the communication protocol and that is usually something you can't easily reverse engineer, but if you plan on the first thing you need to do is get it to respond and react in some way. You will probably not get it to do so by just sending random data to it, since it will interpret it as garbage and simply ignoring it. The only reliable step you can take is trying to find more information about the reader starting with the RFID chip, the store you bought it from, etc. Searching the internet this seems to be more or less your reader: RFID Reader

For the bonus question there is no way to know for sure without information directly printed on the tags, but you can restrict the range by excluding some uncommon types from the format of your tags. Given this: 1. The key-fob tag can either be a 125 kHz or 13.56 MHz; 2. Clam shell cards often come at 125 kHz, 13.56 MHz or 433 MHz; 3. The blank card can either be 125 kHz, 13.56 MHz, UHF EPC Gen 2 (860 - 960 MHz). Rarely I have seen 433 MHz cards like this. 4. I do not know about the key tag. If you could provide more information about it (what is it supposed to do).

From my knowledge there is no single reader which can read all these frequencies, the safest bet is one reader per frequency.

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  • \$\begingroup\$ Actually the reader is the one you linked, but as well as you can see there isn't any information about the communication protocol. No datasheet, no documentation. Zero. That's actually the problem. Argh! And for the bonus question, thanks! Anyway, the key tag is a tag that is supposed to be used at the vending machine. It's called "cashless system". \$\endgroup\$ – Denys Vitali Jan 1 '14 at 12:15
  • \$\begingroup\$ Well then, your only solution is to contact either the seller or the producer of the reader. regarding the key your best bet is still a short-range frequency (125 kHz or 13.56 MHz). Good luck! \$\endgroup\$ – Ionut Ciobanu Jan 1 '14 at 20:28

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