RFID component - what interface?

Hello Forum,

Complete newbie here, excuse me if I use wrong terminology. I just purchased a few components to do a project with, I intend to build an automated counting station for our sheep. It has to be able to read each sheep's RFID and log each session onto an SD card.

This is the first stage, once I get more familiar with the system I would like to have a gsm shield send the data to a server where I can access the data from anywhere or poll the SD card.

I found a reader that looks decent (Wiegand extender module [WIEG-EXT] - $44.00 : Priority 1 Design, Electronics design and manufacturing) but it's available with a RS232 port, usb port and TTL. My question - what interface would be best to get or is it all the same in regards to talking with the Arduino board?

Well, the USB is out. The other two depend on the distance from sensor to Arduino. If only a few feet, or a meter or two, TTL is easiest.

Paul

Thanks, They will be sitting in the same box so TTL it is.