User's Manual

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HID Corporation, 9292 Jeronimo Road, Irvine, CA 92618-1905, USA •Tel: [phone], Fax: [phone]
http://www.hidcorp.com MaxiProx Reader Installation Manual 5375-900 REV 06
Page
13
Note
The customer code is never transmitted or displayed.
4.2
4.2 4.2
4.2 Clock and Data Interface Description
Clock and Data Interface DescriptionClock and Data Interface Description
Clock and Data Interface Description
4.2.1 Clock and Data Message Format
The Clock and Data interface consists of three signals, Card Present, Data and Strobe/Clock. The interface is
a serial data stream, which is controlled with a clock/strobe that indicates when data is valid. All signals are
quiescent high. Card Present goes low when data is about to be sent and remains low until the whole data
stream is completed. Data is the signal that determines the “ones” and “zeros”. Strobe/Clock is the signal
that indicates when data is valid for each cycle.
The Track 2 message format is a stream of binary bits that are grouped into HEX characters. The message
starts with leading zeros, followed by a start sentinel, data, end sentinel, LRC and trailing zeros. Each HEX
character has error correction in the form of a parity bit. Each character consists of five bits. The maximum
number of characters for a magnetic strip card encoded on Track 2 are 40, this product will output less than
40 characters. The data consists only of BCD digits, the remaining HEX digits, A to F, are used for the start
and end sentinel, data separators and control. Only hex B and F are used, A, C D and E are not used. The
message will consist of a minimum of 210 bits.
The bits of a character are in the order 1248P, where parity is odd over the four bits. The LRC is the Xoring
of the message, starting with the start sentinel and ending with the end sentinel. The LRC does not include
the parity bits of the characters in the Xoring. LRC does include its own odd parity bit that covers the four
bits that are the result of the Xoring.
<leading zeros><Start Sentinel><data><data>........<data><End sentinel><LRC><trailing zero>
Customer code 0,1, 63, 72 and 73 (existing customer codes) cards will be read and output in the Track 2
format. The data on these cards will be packed into the Track 2 format in segments of three bits, so the
character does not exceed a BCD seven.
4.2.2
Data Timing
The outputs, Card Present, Data and Strobe are low going signals and the following timing chart describes
the timing.
sentinel parity parity
customer code 10 zeros bit even facility code card number odd
[0 0 0 0 0 0 1] [0 0 0 0 0 0 0 0 0 0] [1] [0] [0 1 1 0 0 1 0 1] [0 0 0 0 0 0 1 1 0 0 1 1 0 0 0 0] [1]
| 0 | 2 | 0 | 0 | 4 | C | A | 0 | 6 | 6 | 1 |
Wiegand Output | 0 | C | A | 0 | 6 | 6 | 1 |
Hex code numbers [ 6 | 5 ][ 0 | 3 | 3 | 0 ]
Decimal conversion [ 101 ][ 0816 ]