MagTek SWIPE READERS WITH 3-TRACK - Manual (Page 14)

Swipe Readers With 3-Track SPI IntelliHead
8
CARD DATA TRANSMISSION TIMEOUTS
The SPI bus timeouts, when card swipe data is available for transmission, are identical to that of
the start up message. When card data is available, after a card swipe, the DAV line will be
asserted high. The Host should respond (transition the SCL line) within 400 mS to prevent a
timeout.
To collect all successive data bits, the Host should respond within 100 mS (i.e., should transition
the SCL line at least once every 100 mS). This corresponds to a new bit collected every 200 mS
for a minimum data rate of 5 bits/second. The maximum collection rate is 100 Kbits/second.
After the card data is transmitted, the reader will erase the card data from its memory and await a
new card swipe. If a timeout occurs during transmission, the remainder of the card data will not
be sent, the card data memory will be erased, and the reader will await a new card swipe.
DATA OUTPUT FORMAT
After a card swipe (forward or reverse), the data is transmitted in the following order:
<CR> <LF> [track 1 data] [track 2 data] [track 3 data] <00h>
Where:
<CR> is an ASCII carriage return (0Dh)
<LF> is an ASCII line feed (0Ah)
[track 1 data], if present, is comprised of a “%” start sentinel character, track 1 card data, and
“?” end sentinel character.
[track 2 data], if present, is comprised of a “;” start sentinel character, track 2 card data, and “?”
end sentinel character.
[track 3 data], if present, is comprised of a “+” start sentinel character, track 3 card data, and “?”
end sentinel character.
<00h> is a binary zero termination character.
If any errors are detected in the card data, for a particular track, the reader will send an “E” for
that track’s card data. For example, if an error is detected in track 3 data, the reader will send
+E? for [track 3 data].
Errors include: character parity error, track data LRC error, and start sentinel found but end
sentinel missing.