All Weather Inc 8339, User Manual, Page: 24 / 69

Model 8339 Ceilometer User’s Manual
18
8339 ASOS CA Command
The 8339 ASOS CA command supports the ASOS regular polling for sensor data. The sensor data
contains sensor status, cloud height information or hits, and monitoring data.
Table 13. Responses to ASOS CA Command
Position Description Value
1 Start of
Transmission
STX
2 Sensor ID (ASCII) C
3 Command Identifier A
4 Sensor Status P or F (Note 1)
6–68 Cloud Height and
Monitoring
Information
AAAAAA HHHHH TTTT VVVV RRRRR
AAAAAA is the status message
(see
Troubleshooting for definition)
HHHHH is the reported cloud height layer (Note 2)
TTTT is the penetration depth in feet (Note 2)
VVVV is the vertical visibility in feet
RRRRR is the range setting in feet
70 Sensor Heater
Energized
0 off
1 if heater is energized
72–73 Checksum CC (Note 3)
74 End of Text ETX
75 Carriage Return CR
76 Line Feed LF
Note 1: "P" (Pass) indicates all diagnostic tests have passed and the sensor is functioning normally.
"F" (Fail) indicates one or more of the diagnostic tests have failed.
Note 2: Cloud height information contains four pairs of height and depth for the detected layers.
Note 3: The checksum is a two-byte field containing an ASCII encoded hex value reserved for a
modulo 256 checksum. The checksum begins with Sensor ID and ends at the last character
before the checksum.