User Manual

Chapter 3
Byte Stream Protocol
Chapter 3
Chapter 3 MR400 RFID Reader Module, Integration Guide
Byte Stream Protocol With the MR 400
The Byte Stream Protocol can be used to communicate with the MR 400 reader, using a two wire serial link
TTL at 115200 baud rate.
Request and Response Packets
The byte stream packet follows generalized packet format for request and response packet. This section
describes the packet format which most request and response examples in this document will use. In practical
implementation, most of the times, these packets are arrays of bytes where elements are arranged as per
specified format.
A general request packet that is being sent to MR400 over host interface must be formatted as follows:
Table 3-1 Byte Stream Packet Descriptions
Field
Number of
Bytes
(Size)
Value Description
SOF 1 0x01 Start Of Frame
Node Address 1 0~0x1F i.e. 0 to 31. Node address that had been set on the reader
Packet
Length
1 See
Description
Size of the packet that is being sent. This should not include the
size of SOF but should include the size of CRC.
Command 1 See
Description
Each Reader API Command corresponds to a number. This
number tells the reader which command to fire. Populate this byte
with the value of the command which you want the reader to fire.
Data Variable See
Description
Depending upon the command you are executing you may need
to send different number of bytes formatted differently. See the
definition of the command you want to execute for more details. A
Typical Request data packet can be 0 to 64 bytes.
CRC 2 (1 for
LSB & 1
for MSB)
Dependent Bitwise inversion of the 16-bit CCITT-CRC of the packet excluding
SOF, with the LSB (Least Significant Byte) first.