Garmin Apollo CNX80 Installation Manaul - page 143
Appendix B - Serial Interface Specifications
GNS 480 (CNX80) Installation Manual
560-0982-01 Rev L
B.1.2.3
“PC-12” Data Format
The format of the fuel input is as follows, which conforms to the PILATUS PC-12 format serial message.
Definition of the input message data that the GNS 480 uses is included in Table B-45.
Baud rate: ............................................... 9600
Data bits: ................................................ 8
Stop bits: ................................................ 1
Parity: ..................................................... none
Expected input rate: ............................... approx. 1.6 second
Message length: ..................................... 13 bytes
The serial input message string is expected in the following format.
Table B-5. Fuel Data Message (PC-12 Format)
Item
Desig
Message
Format
Message
Mnemonic
Field
Width
(bytes)
Message Description
Start
STX
1
Start of Transmission
Units d
UNIT
1 Units
4BH = Kilograms
42H = Pound
Fuel
Quantity
Remaining
dddd
FQ
4
Fuel Quantity Remaining
ASCII-coded decimal format, LSB first.
Example: A fuel remaining value of 432 would be sent as
“2340” (32H,33H,34H,30H)
Fuel
Quantity
Checksum
d
FQCK
1
Fuel Quantity Checksum
Break each decimal value into its BCD representation. Using
BCD arithmetic, sum the 4 BCD values and convert the low-
order PCD digit to and ASCII coded numeric digit.
Example: Checksum for a value of 432 would be “9” (39H)
Fuel Flow dddd
FF
4
Fuel Flow (units/hour)
ACSII-coded decimial format, LSB first. (Same as FQ)
Fuel Flow
Checksum
d
FFCK
1
Fuel Flow Checksum
Sum of fuel flow bytes computed same as FQCK
End
ETX
1
End of Transmission
Note: When for any reason any data is not available is shall be transmitted as dashes (2DH).