ACS AET60 BioCARDKey, Reference Manual

Page: 10 / 24

6.1.2. Extended Command
A command consists of six protocol bytes and a variable number of data bytes and has the following
structure:
byte 1 2 3 4 5 6 ... N+5
(N>0)
N+6
Header Instruction Data Length = N Data Checksum
FF
H
Data Length
N
Header Always 01
H
to indicate the start of a command.
Instruction The instruction code of the command to be carried out by the BioCARDKey.
Data Length Number of subsequent data bytes, and is encoded in 3 bytes. The first byte is FF
H
.
The second byte and the third byte represent data length N.
Data Data contents of the command.
For a READ command, for example, the data bytes would specify the start address
and the number of bytes to be read. For a WRITE command, the data bytes would
specify the start address and the data to be written to the card.
The data bytes can represent values to be written to a card and/or command
parameters such as an address, a counter, etc.
Checksum The checksum is computed by XORing all command bytes including header,
instruction, data length and all data bytes.
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AET60 Reference Manual
Version 1.7
Page 10 of 24
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