VRD-485 RFID READER WITH RS-485 INTERFACE
Revision number: 1.01
Review date: 1 December, 2021
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COMMUNICATION PROTOCOL
Data transmission is performed through the RS-485 interface in asynchronous mode at a baud rates from
2400 to 115200 bit/s. Port setting are: 1 start bit, 8 data bits, parity can be configured, 1 stop bit.
Communication
exchange is organized in packets according to the ‘Master
-
Slave’
principle. Command
packets are transmitted from the control device. Reply packets are sent from the reader to the control
device.
The reader control protocol is Modbus, but it is also possible to operate the reader in a simplified mode, in
which it transmits the code of the read RFID identifier without following the Modbus protocol immediately
upon reading the card. This is done to simplify the work of programmers when a complex solution to a
simple problem is not required.
The reader uses "Holding Registers" to store the basic settings, the code of the identifier, which is in the
field of action and to set the indication. The 0x03 command is recommended to read the identifier code. To
set the reader address and baud rate, use the 0x06 command. To set the indication and reset the RFID
identifier value, use the 0x10 command.
The default reader address is 0x01, the baud rate is 19200 baud, none parity.
If there is no RFID identifier within the reader's field of action, the value of the read RFID identifier is filled
with zeroes.
