Garmin MX20 - Appendix A - I;O Specifications; Moving Map Input

I/O Specifications
MX20 Installation Manual 560-1025-09 Rev E A-1
APPENDIX A - I/O SPECIFICATIONS
This appendix includes the RS-232 serial port interface specifications.
A.1 Moving Map Input
The format of the moving map data output is shown below. Definitions of the input data is included in
Table A-1 and Table A-3. A sample output message is included in Figure A-1.
Baud rate: ...............................................9600
Data bits: ................................................8
Stop bits: ................................................1
Parity: .....................................................none
Output rate: ............................................approx. 1 seconds
Message length: ......................................variable, approx. 83 to 484 characters
The serial output messages are in the following format.
<STX><id><data><it><id><data><it>...<id><data><it><ETX>
<STX> ....................................................ASCII “start of text” character (1 byte, 02h)
<id> ........................................................item designator (1 byte, from following table)
<data> .....................................................item data (format listed in following table)
<it> .........................................................item terminator (1 byte, 0Dh)
<ETX> ...................................................ASCII “end of text” character (1 byte, 03h)
Table A-1. Moving Map ASCII Navigation Data
ID Data Format Length Description
A sddmmhh 9 Present latitude
s =sign: N for north, S for south
dd = degrees
mm = minutes
hh = hundredths of minutes
B sdddmmhh 10 Present longitude
s = sign: E for east, W for west
ddd = degrees
mm = minutes
hh = hundredths of minutes
C ddd 3 Track (magnetic): ddd = degrees
D ddd 3 Ground speed: ddd = knots
E ddddd 5 Distance to active waypoint: ddddd = nm x 10
G sdddd 5 Cross track error:
s = sign: R for right, L for left of course
dddd = distance off course, hundredths of nm
I dddd 4 Desired track (magnetic):
dddd = degrees x 10
K ddd[dd] 3 to 5 Active waypoint identifier:
ddd[dd] = ASCII waypoint identifier
L dddd 4 Bearing to active waypoint (magnetic):
dddd = degrees x 10
Q sddd 4 Magnetic variation:
s = sign: E for east, W for west
ddd = degrees x 10
T ---A----- 9 Warnings: The 4th character will be an “A” when the
navigation data is flagged, otherwise, all characters will be
dashed. All other navigation data will be dashed when it is
flagged.