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Serial Interface Specifications
Apollo GX50/60/65 Installation Manual
67
ALTITUDE ENCODER/CONVERTER INPUT
The format of the altitude input is as follows. Definition of the input message is included in
Table 11. Several sample messages are illustrated in Figure 19.
Baud rate: ......................................... 1200
Data bits: .......................................... 8
Stop bits: .......................................... 1
Parity: ............................................... none
Expected input rate: .......................... approx. 1 second
Message length: ................................ 17 characters
Table 11 Altitude Input Data
Byte Data Format Description
1 “#” ASCII “#” (023h)
2 “A” ASCII “A” (041h)
3 “L” ASCII “L” (04Ch)
4 “ “ ASCII space (020h)
5 “+” or “-” Altitude sign: ASCII “+” or “-” (02Bh or 02Dh)
6-10 ddddd Altitude in feet, right justified with leading zeros
11 “T” ASCII “T” (054h)
12 “+” or “-” Temperature sign: ASCII “+” or “-” (02Bh or 02Dh)
13-14 dd Internal altimeter temperature
15-16 dd Checksum of bytes 1 through 14, computed in hex, output in
ASCII format (i.e., “FA” hex)
17 <CR> ASCII carriage return (0Dh)
The altitude input can decode several status or error codes. These codes would be in place of
the altitude data in characters 5 - 10 as follows.
“-09980”............................................ Heater not ready: expected during encoder warm-up
or if there is a loss of signal from the encoder.
“-09981”............................................ Possible hardware problem: expected from encoder
indicating a temperature greater than 55°C or if data
is invalid.
“-09982”............................................ Altitude out of range: expected from the encoder
indicating that the altitude is outside specified range
of the encoder.