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B KLN 94
Rev. 4, Jan/2003 10599I04.CDL Page A-3
Fuel/air data input protocol
Fuel/air data sent by the Airdata computer shall be received in a block having one of the following
formats:
FORMAT A (13 BYTE ASCII STRING)
BYTE DESCRIPTION / FORMAT
1 STX (ASCII code 02H)
2 Unit of Measure
G = .1 gallon
I = .1 imperial gallon
L = 1 liter
K = 1 kilogram
B = 1 pound
3-6 Fuel Remaining
ASCII-coded decimal format, LSB first
Example:
A fuel remaining value of 432 would be sent as “2340” (32H, 33H, 34H, 30H).
7 Fuel Remaining Checksum:
Break each decimal value into BCD representation. Using BCD arithmetic, sum the 4
BCD values and convert the lower-order BCD digit to an ASCII coded numeric digit.
Example:
The checksum for a value of 432 would be “9” (39H).
8-11 Fuel Flow Rate (units / hours)
ASCII-coded decimal format as used for Fuel Remaining.
12 Fuel Flow Rate Checksum
Sum of fuel flow rate bytes computed as described for Fuel Remaining checksum.
13 EXT (ASCII code 03H)
NOTE:
1. Fuel remaining and fuel flow rate information shall be for the complete aircraft.
2. This 13 byte record shall be transmitted every 1.6 seconds ± 0.16 seconds.