Garmin Apollo CNX80, Installation Manual

Page: 119 / 168

Appendix B - Serial Interface Specifications
Apollo CNX80 Installation Manual 560-0982-00 Rev D B-3
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 CNX80 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
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)
<checksum>...........................................the message checksum, same format as message
<ETX> ..................................................ASCII “end of text” character (ETX = 03h)
Table B- 3 - Fuel/Air Data Message Data (S Format)
Item
Desig
Message
Format Message
Mnemonic Field
Width
Message Description
SA ddd IAS 7 Indicated Air Speed in knots
SB ddd TAS 7 True Air Speed in knots
SC ddd MACH 7 Mach Speed in thousandths
SD sdddd PALT 9 Pressure Altitude in tens of feet, +/- sea level
SE sdddd DALT 9 Density Altitude in tens of feet, +/- sea level
SF sdd OAT 7 Outside Air Temp - or “Total”, in degrees Celsius
SG sdd TAT 7 True Air Temp - or “Static”, in degrees Celsius
SH ddd WDIR 7 Wind Direction, 0 to 359 degrees from true north
SI ddd WSPD 7 Wind Speed in knots
SJ sdd TURN 7 Rate of Turn in +/- degrees/second, + is right, - is left
SK sddd VSPD 8 Vertical speed in tens of feet/minute
SL ddd HEAD 7 Heading, 0 to 359 degrees from true north
SM dddd RFF 8 Right Engine Fuel Flow in tenths of gallons/hour
SN ddddd RFU 9 Right Engine Fuel Used in tenths of gallons
SO dddd LFF 8 Left Engine Fuel Flow in tenths of gallons/hour
SP ddddd LFU 9 Left Engine Fuel Used in tenths of gallons
SQ ddd ERR 7 Error Log / Reason Indicator: 001 = temp sensor error; 000