GTN 625/635/650 TSO Installation Manual
Page B-5
190-01004-02
Rev. C
B.2 GTN RS-232 FUEL/AIR DATA INPUT FORMAT
B.2.1 Electrical Interface
The input signals are compatible with RS-232C. Data is input at 9600 baud with a word length of 8 bits,
one stop bit, and no parity. One message is received per second.
B.2.2 Shadin Altitude Sentence
The Garmin GTN is capable of receiving the following 17-byte message from Shadin Altitude Encoders,
Altitude Serializers, and Altitude Converters:
RMS<sp><+/->12345T<+/->12ul<CR>
Where:
RMS
ASCII characters
<sp>
space (0x20)
<+/->
sign indicator (0x2b["+"] or 0x2d["-"])
12345
altitude in feet
T
ASCII character
<+/->
sign indicator
12
sensor temperature
ul
checksum of bytes 1 through 14 in hex ASCII (i.e., "FA")
<CR>
carriage return (0x0d)
Note
: Checksum is calculated by adding each byte in the message (1 through 14).
B.2.3 Icarus Altitude Sentence
The Garmin GTN is capable of receiving the following 10-byte message from the Icarus Altitude
Serializer:
ALT<sp>12345<CR>
Where:
ALT
ASCII characters
<sp>
space (0x20)
12345
altitude in feet
<CR>
carriage return (0x0d)
