ACS ACK30 Smart Keyboard - Manual (Page 17)

ACR30 Reference Manual
Version 3.3 January 2009 Page 17 of 44
ACR30
Card Status Message for Card Insertion
byte 1 2 3 4 5
Header SW1 SW2 Data
length
Checksu
m
01
H
FF
H
01
H
00
H
FF
H
Card Status Message for Card Removal
byte 1 2 3 4 5
Header SW1 SW2 Data
length
Checksu
m
01
H
FF
H
02
H
00
H
FC
H
A card status message is transmitted only once for every card insertion or removal event. The reader
does not expect an acknowledge signal from the computer. After transmitting a status message, the
reader waits for the next command from the computer.
NOTE - If the card is being removed from the reader while a card command is being executed, the reader will
transmit a normal response to the computer with the response status bytes indicating the card removal during
command execution (see Appendix B: Response Status Codes).
8.5. Transmission Protocol
The start of a command (to the reader) or a response (from the reader, including the Reset Message
and Card Status Messages) is indicated by the respective party through the transmission of the single
byte Start-of-Text (STX) character with the value 02
H
.
The end of a command or response is indicated through the single byte End-of-Text (ETX) character
with the value 03
H
.
Within the command and response transmission only ASCII characters representing the hexadecimal
(hex) digits 0...F are used. Each byte of a command or response is splitted into its upper and lower
halfbyte (nibble). For each halfbyte is transmitted the ASCII character representing the respective hex
digit value. For example, to transmit the data byte 3A
H
, two bytes are actually sent on the interface,
namely, 33
H
(ASCII code for '3') followed by 41
H
(ASCII code for 'A'):
Data byte value 3A
H
Transmitted values 33
H
= '3' 41
H
= 'A'
The following example shows the transmission of a command with instruction code A2
H
and one data
byte with the value 3D
H
. The command has the following structure: