RFID is Radio Frequency IDentification. These readers are used to read the unique sequence number present in EM4100 family transponder tags. The reader can be connected to a PC through the serial port. The baud rate of RFID reader is 9600 bps and it can be changed. All communication is 8 data bits with no parity bit and one stop bit. Usually any tag using EM4102 protocol can be used.
RFID transponder tag is a passive tag. It become active when it receive radio frequency wave from the RFID reader. The range of activation is 10-15 cm from the reader. When a tag is brought near a reader it continuously sent the unique sequence present in it. The unique sequence is 10byte long and with a starting and stopping byte, thus a total of 12 bytes. OA1F4320B0 is an example of the unique sequence number.
The electrical specification of the reader is a current less than 110mA and voltage range of 7 to 9V. It produce a radio wave of frequency 125 KHz.
When the reader is powered a green LED will be ON on the board. When the built in antenna starts transmitting the red LED starts blinking. The tag must be brought parallel to the reader. The red LED starts blinking rapidly when the reader starts reading the sequence.
We have to write a code to extract this sequence to our embedded board or PC. Then we have to sent this sequence to the appengine. It must be stored there along with the name of the reader and time of reading. The data should be available for later manipulation.