25 July 1996
Micro-reader Module
3
.
Communications Protocol
3.1 Protocol PC to Micro-reader
Start Length
BCC
Cmd 1 Cmd 2 Data
Byte
Contents (hexadecimal value)
0
Start Mark (SOH, 01hex)
1
Length
2
Command Field (1)
3
Command Field (2) (optional)
4(3)
Data Field (1)
.
.
N+3(2) Data Field (N)
N+4(3) BCC
Note:
The total number of bytes sent within a protocol frame (including Start Mark and
BCC) is limited to 41 bytes.
Examples are given in Section 6.1.
3.1.1 Start Mark
The ‘Start-Mark’ signifies the beginning of a message. It is represented by the ASCII character SOH
(Start Of Header, 01hex).
3.1.2 Length
The ‘Length’ byte indicates the length, in bytes, of the following Command and Data Fields.
