User's Manual

3 | P a g e www.eccel.co.uk
2 Communication interface
2.1 Overview
The RS485 RFID Reader can be controlled using a simple binary protocol available over RS485. This binary
protocol was designed to be as simple as possible to implement on the host side whilst still providing robust
communication.
The default baud rate is 115200bps, and can be changed from 9600 up to 115200. Other protocol settings
are: data bits: 8, parity: None, Stop bits: 1, flow control: None.
2.2 Frame structure
Communication with the module is symmetric. So, frames sent to and received from the module are coded
in the same way. All frames contain fields as described in the table below. The reader should answer only
to commands with an address byte equal to its own device address.
The length of the command is the sum of the Address byte + Command body + 2 bytes CRC.
Frame
STX
Command
length
Command
length XOR
Address byte
Command body
CRC16
1
-
byte
2
-
2
-
1
-
byte
1
-
byte
n
-
bytes
2
-
0xF5
Command
body
length, LSB,
maximum
value 1024
XOR with
0xffff
of
command
length
bytes
Address byte
Command
Command
parameters
Address +
Command
body CRC