Campbell Scientific CSAT3 3-D Sonic Anemometer - Manual (Page 32)

CSAT3 Three Dimensional Sonic Anemometer
Ux Input Location: The Input Location to store the first of five data values to
an EDLOG datalogger. The CSAT3 returns the following data after receiving
the “Trigger and Get Data” or “Get Data after a Group Trigger” command in
the option parameter: u
x
, u
y
, u
z
, c or T
s
, and a diagnostic word, where u
x
, u
y
,
and u
z
are the wind speeds along the x, y, and z axes defined by the
anemometer head (see FIGURE 4-1), c is the speed of sound, and T
s
is the
sonic virtual temperature. The wind speed and the speed of sound are in units
of m s –1 , and T
s
is in degrees Celsius. If the Reps option in parameter 1 is
greater than 1, the number of sequential Input Locations used is Reps ∗ 5.
10.4 Diagnostic Word
The fifth output from the CSAT3 is the diagnostic word. The diagnostic word
describes the status of the anemometer and is useful in filtering data. For
example, when the anemometer is locking in on the ultrasonic signals after
receiving the acquire signals command, the NaN or -99999’s it sends to the
datalogger for the science data can be filtered out of the statistics based on the
diagnostic word, see the example program in Section 10.6 and 10.7.
The CSAT3 ()/SDM-CSAT3 instruction (P107), decodes the diagnostic word
and represents it in base 10. The bits in the diagnostic word are grouped
together into three categories. Bits 15 through 12 are four diagnostic flags (see
TABLE 10-5 and TABLE 10-6), bits 11 through 6 represent the range the
measurements are reported in (used by the datalogger), and bits 5 through 0 are
a counter. A detailed description of decoding the diagnostic word is given in
Appendix B.
TABLE 10-5. Diagnostic Word
Diagnostic Word
b15 - b12 b11 b10 b09 b08 b07 b06 b05 - b00
diagnostic flags u
x
range u
y
range u
z
range counter
The following are four specific Diagnostic Words (Base 10) and the situation
that produces them:
NaN or -99999, Anemometer does not Respond. This is the special case when
the datalogger attempts to address an anemometer and the anemometer does
not answer. This occurs if the anemometer is not connected to the SDM bus,
the anemometer is not connected to a 12 Vdc power supply, or none of the
anemometers on the SDM bus are set to the SDM address in the
CSAT3 ()/SDM-CSAT3 (P107) instruction.
61440, Lost Trigger. The anemometer has lost the trigger source, in this case
all the diagnostic bits are set high, the range bits are set low, and the counter
bits are low. This occurs if the anemometer is disconnected from the SDM
bus; e.g. a loose SDM clock line. To bring the anemometer back on-line,
connect the CSAT3 to the SDM bus and execute the CSAT3 ()/SDM-CSAT3
(P107) instruction with the “Set Execution Parameter” Command/Option.
61503, No Data Available. The anemometer has no new data. In this case all
the diagnostic bits are set high, the range bits are low, and all the counter bits
are high. This occurs immediately after the anemometer receives the acquire
signal command from the datalogger, e.g. a CSAT3 ()/SDM-CSAT3 (P107)
instruction with the “Set Execution Parameter” Command/Option. The no new
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