Instruction manual

CSAT3 THREE DIMENSIONAL SONIC ANEMOMETER
12
-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 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 SDM-
CSAT3 (P107) instruction with the “Set
Execution Parameter” option in parameter 3.
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,
i.e. an SDM-CSAT3 (P107) instruction with the
“Set Execution Parameter” option in parameter
3. The no new data condition also occurs when
the datalogger’s execution frequency (inverse of
the execution interval) is much greater than the
execution parameter the anemometer was told
to use.
61441, SDM Communications Error.
The
datalogger and CSAT3 are unable to
communicate correctly. Extending the SDM
cable beyond the standard 7.62 m (25 ft.) and
not slowing down the SDM clock with Instruction
115 (CR23X or CR10(X)) or 108 (21X) is the
most common cause of this error. See
Appendix D for details on identifying the
appropriate SDM clock rate for a given cable
length.
10.3 SDM-GROUP TRIGGER (P110)
An SDM Input/Output Instruction that controls
SDM devices that support the group trigger
protocol, including the CSAT3. Up to 15 group
trigger devices can be connected to the SDM
bus. With the SDM Group Trigger (P110), all
group trigger devices are triggered to make
simultaneous measurements. The data from
each device is then retrieved with the
appropriate device specific instruction. For the
CSAT3, the SDM-CSAT3 (P107) Instruction
with the “Get data after Group Trigger” options
(Option 97, 98, or 99) in parameter 3 is used to
retrieve the data.
10.4 EXAMPLE DATALOGGER PROGRAM
In the following example, a CR23X is used to
configure and then collect data from the CSAT3
using SDM communications. The CR23X will
trigger each wind measurement over the SDM
bus and retrieve wind speed data. An example
flux program is given in Appendix A.
TABLE 10-5. CSAT3 Diagnostic Flags
Bit Set High Description Comment
b15 Difference in the speed of sound
between the three non orthogonal
axes is greater than 2.360 m s
-1
(~ 4°C @ 25°C)
The anemometer path length may have
been altered or the anemometer head is
broken.
b14 Poor signal lock There may be an obstruction in the
anemometer path or on the transducer
face.
b13 Sonic signal amplitude too high An obstruction, in the anemometer path or
on the transducer face, was removed.
b12 Sonic signal amplitude too low There may be an obstruction in the
anemometer path or on the transducer
face.