MaxiProx
®
Installation Guide
Part No. 5375-901, Rev E.1
March 2012
Page 19 of 19
© 2008-2012 HID Global Corporation. All rights reserved.
4.3
RS232 and RS422 Card Message Specification
(Send Mode Only)
When Access Cards (transponders) are presented to the MaxiProx reader, the reader sends a
message. The message is in the following format:
CCDDDDDDDDDDXX<CR><LF>
^ First character sent
All characters
C, D
and
X
are ASCII encoded, hexadecimal digits. (i.e., the hex value
7
is sent as an
ASCII character 7 or the hex value
E
is sent as an ASCII character
E
).
The
CC
field is reserved for use by HID Global Corporation. The valid values are
00
through
7F
.
The
DDDDDDDDDD
field is the transponders (Access Card) data. The valid values are
0000000000
through
1FFFFFFFFF
(ASCII).
The
XX
field is a computed checksum. The checksum is calculated by first grouping the message data
into the pairs
CC DD DD DD DD DD
. Each pair of characters represents one byte of data. Then each pair of
characters is converted from ASCII to their respective hex values. At this point, the 6 bytes are added
together. The checksum is equal to the least significant 8 bits of the result.
<CR>
is the ASCII code for a carriage return. (
0D
hex)
<LF>
is the ASCII code for a line feed. (
0A
hex)
For example, if the MaxiProx reads a transponder (Access Card) that contains the value
CC=00
and
DDDDDDDDDD=01234ABCDE
, the reader will report the ASCII message
0001234ABCDE08<CR><LF>.
Note:
Each of the characters is ASCII encoded. The actual bytes (hex value) that are sent to the host
are:
<30><30><30><31><32><33><34><41><42><43><44><45><30><38><0D><0A>
The checksum was computed by adding
00 + 01 + 23 + 4A + BC + DE = 208
hex. The checksum is the least
significant 8 bits of this result or 08 hex. The communications settings are 9600-75Hz BAUD, 8 bits, 1
stop bit, no parity.
