Rs-232 Inputs; Fuel/Air Data Input - Honeywell KLN 90B Installation Manual

BENDIX/KING

1.3 RS-232 INPUTS

1.3.1

FUEL/AIR DATA INPUT

One of the following 4 ASCII formats shall be transmitted. Any data which is not valid shall be in-
dicated by dashes (ASCII 2DH).
Format A
A 13 byte ASCII string shall be transmitted per the following format:
Byte Data
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 its BCD representation. Using BCD arithmetic, sum the 4 BCD val-
ues and convert the low-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/hour)
ASCII-coded decimal format as for Fuel Remaining.
12 Fuel Flow Rate Checksum
Sum of fuel flow bytes computed as for Fuel Remaining.
13 ETX (ASCII code 03H)
This 13 byte record shall be transmitted every 1.6 sec $.16 sec.
Fuel remaining and fuel flow rate information shall be for the complete aircraft.
Format B
A 52 byte ASCII string shall be transmitted per the following format:
Byte Data
1 STX (ASCII code 02 hex)
2 Units of Measure
G = gallons
I = Imperial gallons
L = liters
K = kilograms
B = pounds
3-8 Total Fuel Remaining
Page A-10 10521I05.TDC
KLN 90B
Rev 5, April/2003