User's Manual Part 3

Hi-G-Tek Ltd. Microelectronics & Asset Tracking Technology
119
6
RS 485/232 Communication Protocol
6.4. String Formats.
6.4.1. LSC to READERS messages.
Commands & Acknowledge strings:
STX #B R# CMND data CRC ETX
1 2 2 2 n 2 1
# of bytes
#B
CRC
Where:
STX This is the marker for the beginning of the
messages. STX = 02 hex.
#B String length, the string contains the R#,CMND,
the DATA field, and the CRC.
R# This session's READER address .
CMND This session's command code .
DATA The data field contains the data required to execute
the command
CRC This is the cyclic redundancy check for DATA and
fields #B, R#, CMND.
ETX This is the marker for the end of the messages.
ETX = 03 hex.
6.4.1.1. CRC Calculation.
CRC calculations are based on the following CCITT polynomial:
16 12 5
X + X + X + 1
The result is 2 bytes.