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

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)
ID Data Format
A sddmmhh
B sdddmmhh
C ddd
D ddd
E ddddd
G sdddd
I dddd
K ddd[dd]
L dddd
Q sddd
T ---A-----
MX20 Installation Manual
Table A-1. Moving Map ASCII Navigation Data
Length Description
9 Present latitude
s =sign: N for north, S for south
dd = degrees
mm = minutes
hh = hundredths of minutes
10 Present longitude
s = sign: E for east, W for west
ddd = degrees
mm = minutes
hh = hundredths of minutes
3 Track (magnetic): ddd = degrees
3 Ground speed: ddd = knots
5 Distance to active waypoint: ddddd = nm x 10
5 Cross track error:
s = sign: R for right, L for left of course
dddd = distance off course, hundredths of nm
4 Desired track (magnetic):
dddd = degrees x 10
3 to 5 Active waypoint identifier:
ddd[dd] = ASCII waypoint identifier
4 Bearing to active waypoint (magnetic):
dddd = degrees x 10
4 Magnetic variation:
s = sign: E for east, W for west
ddd = degrees x 10
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.
560-1025-09 Rev E
I/O Specifications
A-1