Appendix B Gtr/Gnc Data Format; Aviation Format - Garmin GTR 225 Installation Manual

APPENDIX B GTR/GNC DATA FORMAT

B.1 RS-232 Aviation Format
B.1.1 Electrical Interface
The I/O signals are compatible with RS-232C. Data is generated at 9600 baud with a word length of 8 bits,
one stop bit, and no parity.
B.1.2 General Aviation Output Format
The GTR/GNC RS-232 data has the following general format:
STX - ASCII start-of-text character (02 hex)
t1s - Type 1 output sentences (see following paragraphs for description)
t2s - One or more type 2 output sentences (see following paragraphs for description)
ETX - ASCII end-of-text character (03 hex)
B.1.3 Aviation Output Sentence Type 1
The Type 1 output sentences have the following general format:
id - item designator (single ASCII alphabetic character)
dddd - item data (1 to 10 printable ASCII characters)
CR - ASCII carriage return character (0D hex)
LF - ASCII line feed character (0A hex)[1]
Note:
[1] The line feed character is not output if the RS-232 port is configured as "Aviation Output 2."
Each Type 1 sentence is output by the GTR/GNC approximately once every second.
The track, desired track, and bearing to waypoint angles, and the magnetic variation are output according
to the current mode of the GTR/GNC (automatic magnetic heading, magnetic variation computed at last
known position; true heading, magnetic variation of E00.0°; or user-defined magnetic heading, magnetic
variation as entered by user).
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Rev. F
GTR 225/GNC 255 TSO Installation Manual
Page B-1