Getting data from an RFID reader

Question

I have a an RFID reader with very scant documentation. It has some wires hanging out and they come from a connector with "+12V", "GND", "NC" , "COM" (or CDM) , "NO", "SW", "D0" , "D1" pins.

I don't know what they are but "+12V" and "GND" are for voltage and ground. Probably D0 and D1 are for I2C communication.

The unit works fine (beeps while reading from RFID card etc) but I'd like to get the info of the cards to a laptop using a serial (COM) port. I don't want to damage the serial port of my laptop. How would I go about trying to receive data from the RFID reader. I can try on another Windows XP laptop which is expendable.

My guess is to connect the D0 and D1 to the serial port but which pins do I connect? What about the voltage? I am familiar with RX and TX port usage. I just want to know that I can get data off the RFID reader and if so I'll write a more robust com send/receive C program.

Answer 1

D0 stands for Data Low pin. D1 stands for Data High pin.

From the description of yours, you might be using Wiegand based RFID reader. The pin connection present here RFID reader. The pins D0 and D1 are used to send data to controller.

1. When D0 and D1 are both Low or 0 that means no data is transmitting.
2. When D0 is Low and D1 is high (1) then the output 0 is transmitting.
3. When D0 is High and D1 is Low then the output 1 is transmitting.
4. When D0 and D1 are both High or 1 that means no data is transmitting.

So when you connect these two pins to some controller, it has to monitor the data from these two pins and has to determine the output (logic 0 or 1) based on the above four points. After controller reading all the data from D0 and D1 (may be 96 or 128 consecutive bits), you need to decode that binary data into ASCII first and then you can extract card number from that data.

Answer 2

Well you'll first need to make the RS232 connector. Your pins are as follows:

+12V: Hot voltage supply GND: Ground

^^Connect those to a power 12V power supply.

NC: Normally closed COM: Common NO: Normally open SW: Switch D0: Data 0 D1: Data 1

There should be at least some documentation with the device as to which pins communicate. Look up RS232 9 pin wiring to see what you should solder where.

Then you'll need a Serial communication program that can send or at least receive communications from the device. Putty would be your best bet.