Fuel /Air Datac - Garmin GNS 480 Installation Manual

Appendix B - Serial Interface Specifications
B.1.2 Fuel/Air Data Computer Input
The fuel/air data input is used to input fuel flow and airdata computer information from the fuel/air data
computer. Both the Shadin "S" format and Shadin "Z" format data are automatically accepted.
B.1.2.1 "S" Data Format
The format of the fuel/air data computer input is as follows, which conforms to the Shadin "S" format
serial message. Definition of the input message data that the GNS 480 uses is included in Table B- 3. A
sample input message is illustrated in Figure B- 2.
Baud rate: ...............................................9600
Data bits: ................................................8
Stop bits: ................................................1
Parity: .....................................................none
Expected input rate: ...............................approx. 1 second
Message length: ......................................variable (512 character max.)
The serial input message string is expected in the following format.
<STX><message><message> ... <message><chksum><ETX>
<STX>.....................................................ASCII "start of text" character (STX = 02h)
<message>...............................................starts with an ASCII "S", then an ID character, followed
<checksum> ............................................the message checksum, same format as message
<ETX> ....................................................ASCII "end of text" character (ETX = 03h)
Item Message
Desig Format
SA ddd
SB ddd
SC ddd
SD sdddd
SE sdddd
SF sdd
SG sdd
SH ddd
SI ddd
SJ sdd
SK sddd
SL ddd
SM dddd
SN ddddd
SO dddd
SP ddddd
SQ ddd
B-4
by the message data, a carriage return (CR = 0Dh), and a
line feed (LF = 0Ah) See the following table. s = a sign
indicator (-,+,E,W). d = a decimal digit (0-9)
Table B- 3 - Fuel/Air Data Message Data (S Format)
Message Field Message Description
Mnemonic Width
IAS 7 Indicated Air Speed in knots
TAS 7 True Air Speed in knots
MACH 7 Mach Speed in thousandths
PALT 9 Pressure Altitude in tens of feet, +/- sea level
DALT 9 Density Altitude in tens of feet, +/- sea level
OAT 7 Outside Air Temp - or "Total", in degrees Celsius
TAT 7 True Air Temp - or "Static", in degrees Celsius
WDIR 7 Wind Direction, 0 to 359 degrees from true north
WSPD 7 Wind Speed in knots
TURN 7 Rate of Turn in +/- degrees/second, + is right, - is left
VSPD 8 Vertical speed in tens of feet/minute
HEAD 7 Heading, 0 to 359 degrees from true north
RFF 8 Right Engine Fuel Flow in tenths of gallons/hour
RFU 9 Right Engine Fuel Used in tenths of gallons
LFF 8 Left Engine Fuel Flow in tenths of gallons/hour
LFU 9 Left Engine Fuel Used in tenths of gallons
ERR 7 Error Log / Reason Indicator: 001 = temp sensor error; 000
= no errors
560-0982-01 Rev A GNS 480 (CNX80) Installation Manual