System Description
System Description and Installation Manual for MXS ICD10004-01
© Sagetech Corporation 2018 Confidential Proprietary Export-Controlled Page 64 of 160
Pressure Altitude
Byte Offset
Byte Name Field Description
03
ALT0
ALT0 ALT1 ALT2 Pressure Altitude
04
ALT1 0xFF
0x00
0x01
0xFB
0x00
0xEE
0x50
0x00
0xEC
-1200 ft
0 ft
126,700 ft
05
ALT2
Pressure Altitude
The Transponder always provides the current altitude from the current altitude source here. The data is
barometric altitude in feet with reference to a pressure of 29.9213” Hg (101325 Pascals) for zero feet
indication. The MSB is sent first.
The data is a 24-bit signed 2's complement integer, in units of feet. The value 0x800000 is used to
indicate invalid altitude; all other values reported in this message are valid altitudes.
Table 0-2830 Acknowledge Message Example Data
Message Field Byte Values (original) Byte Message Content
(Hex)
Start Byte
AA [ AA ]
Message Type
0x80 Acknowledge Message [ 80 ]
Message ID
An arbitrary number between 0 and 255 (inclusive) that uniquely identifies the
message.
[ 00 ]
Payload Length
6 [ 06]
PAYLOAD
ACK’d Message
Type
Operating Message Type
[ 03]
ACK’d Message ID
0
[ 00 ]
System State Byte
System Fail Flag and Weight on Wheels are set.
[ 0A ]
Pressure Altitude
8,000 feet
[ 00 1F 40 ]
Checksum
8-bit arithmetic sum of message from Start Byte to last byte of the Payload
Data.
[ 9C ]