R21C series it's a 13.56Mhz a Desktop Universal MF card Reader( Read only type) with a standard serial port, can read the card serial number and send to computer. Reader distance up to 80mm, it’s not only simple aspect, but also stable and reliable data. Widely used for RFID Radio Frequency Identification system and project, Such as Automated parking management system, Personal identification, Access controller, Production Access control, etc
Ⅰ Technical Parameters

Ⅱ Instructions for use
Method of installation and use
1. Connect with computer through a serial cable directly. When the buzzer sounded, reader into the self-inspection. And the same time, LED turn into red means standby.
2. Open the output of computer software,such as Serial debugging assistant.
3. Put tag on the top of reader, the software will output a data(card number) of the tag. When reading the tag, LED light change from red to green.
Detecting device is connected

Open the Device Manager of computer, If appears Device and “COM” port is OK that means Reader has successfully into computer.

Ⅲ Communication Format
RS232 Communication
9600 bps, none parity, 8 data bits, 1 stop bit
Data Format

The following table describes the packet fields

Example:  02 0A 01 06 00 8E 6D 5D B0 03 
STX: 02
Length: 0A, 9 bytes
CardType: 01, MF
SNR: 06 00 8E 6D 5D, 06 = batch number, 00 8E 6D 5D = 0009334109 (DEC)
BCC: B0,  B0 = 0A xor 02 xor 06 xor 00 xor 8E xor 6D xor 5D
EXT: 03
Ⅳ Precautions
1. Do not install the reader on the magnetic objects and metal objects, they will seriously affect the RF signal.
2. If after reading, the tag is still in the induction zone, the RF reader will not send data and without any hints.
Ⅴ Common problems
1. Operation without feedback: Please check whether the interface plugged in, whether the tag is a valid or whether another RF tag is within the reading range.
2. Data error: Please check Whether the mouse is moved, whether the reader is in a critical state and whether the cable length is too long.