Campbell Scientific CR9000X Measurement and Control System - Manual (Page 219)

Section 6. Data Table Declarations and Output Processing Instructions
WindVector (Repetitions, Speed/East, Direction/North, DataType,
DisableVar, Subinterval, SensorType, OutputOpt)
WindVector processes wind speed and direction from either polar (wind speed
and direction) or orthogonal (fixed East and North propellers) sensors. It uses
the raw data to generate the mean wind speed, the mean wind vector magnitude,
and the mean wind vector direction over an output interval. Two different
calculations of wind vector direction (and standard deviation of wind vector
direction) are available, one of which is weighted for wind speed.
When used with polar sensors, the instruction does a modulo divide by 360 on
wind direction, which allows the wind direction (in degrees) to be 0 to 360, 0 to
540, less than 0, or greater than 540.
The ability to handle a negative reading is useful where a difficult
to reach wind vane is improperly oriented. For example, a vane
outputs 0 degrees at a true reading of 340 degrees. The simplest
solution is to enter an offset of -20 in the instruction measuring
the wind vane, which results in 0 to 360 degrees following the
modulo divide. NOTE
When a wind speed sample is 0, the instruction uses 0 to process scalar or
resultant vector wind speed and standard deviation, but the sample is not used
in the computation of wind direction. The user may not want a sample less than
the sensor threshold used in the standard deviation. If this is the case, Write the
datalogger program to check wind speed, and if it is less than the threshold set
the wind speed variable equal to 0 prior to calling the data table.
Parameter
& Data Type Enter WINDVECTOR PARAMETERS
Repetitions
Constant Number of wind vector averages to calculate.
Speed/East
Dir/North
Vars or Array The source variables for wind speed and direction or, in the case of orthogonal sensors,
East and North wind speeds. If repetitions are greater than 1 the source variables must be
arrays containing elements for all repetitions.
DataType A code to select the data storage format. Read More: See Section 4.2.4.4 Data Types
Constant Alpha Code Numeric Code Data Format
IEEE4 24 IEEE 4 byte floating point
FP2 7 Campbell Scientific 2 byte floating point
UINT2 21 2 Byte unsigned integer
Long 20 4 Byte Integer value
DisableVar
Constant,
Variable, or
Expression
A non-zero value will disable intermediate processing. Normally 0 is entered so all inputs
are processed. For example, when the disable variable is 0 the current input is not
included in the total. The total that is eventually stored is the total of the inputs that
occurred while the disable variable was 0.
Value Result
0 Process current input
≠ 0 Do not process current input
Subinterval
Constant
Number of samples per sub-interval calculation. Enter 0 for no sub-interval calculations.
SensorType The type of wind sensors
Constant Value Sensor Type
0 Speed and Direction
1 East and North
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