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1.8 Serial Communication Protocol :
Protocol is user selectable by grounding or leaving open pins 2 ,9 or 10 of the 15
pin D-Subminiature connector, or by selecting protocols via software see
'4.6. Hardware jumpers override software settings!
Leaving pin 9 and 10 of the DA-15S connector open results in the default
protocol compatible with UPS Aviation Technologies= (IIMorrow) Navigation
devices. At a baud rate of 1200 bps the Digitizer sends a seventeen byte message
beginning with # AL, then a space followed by five altitude bytes; the letter AT@
and the number A25@; two checksum bytes and a carriage return.
Examples of serial messages for (IIMorrow) devices:
Message:
#AL+00800T+25D8 r
Grounding pin 10 of the DA-15S connector results in a protocol compatible
with some navigation devices manufactured by Trimble and Garmin. At a baud
rate of 9600 bps the Digitizer sends a ten byte message. The message begins with
ALT followed by a space and five altitude bytes; concluding with a carriage
return. Examples of serial messages for Trimble or Garmin devices:
Message:
ALT 99900 r
ALT 10500 r
Grounding pin 9 of the DA-15S connector results in a protocol compatible with
some navigation devices manufactured by Northstar and Garmin. At a baud rate
of 2400 bps the Digitizer sends a 10 byte message. The message begins with ALT
followed by a space and five altitude bytes; concluding with a carriage return.
Examples of serial messages for these devices:
Message
ALT 02500 r
ALT -2500 r
Grounding both pins 9 and 10 of the DA-15S connector results in a protocol
compatible with some navigation devices manufactured by Magellan. At a baud
rate of 1200 bps the Digitizer sends a seventeen byte message beginning with
$MGL, followed by a +/- sign and five altitude digits, then T+25, a checksum and
concludes with a carriage return. Examples of serial messages for Magellan
devices:
Message
$MGL+02500T+25D6 r
Definition:
Altitude 800 feet.
Definition:
Digitizer disabled.
Altitude 10,500 feet.
Definition:
Altitude 2500 feet.
Digitizer disabled.
Definition:
Altitude 2500 feet.
-8-
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