Campbell 03002, Instruction Manual

Page: 23 / 39

R.M. Young Wind Sentry
14
TABLE 7-3 lists the multipliers (M) and offsets (Off) to obtain meters/second
or miles/hour when the Pulse Count instruction is configured to output the
result in hertz.
TABLE 7-3. Wind Speed Multiplier
(With Pulse Channel Configuration Set to Low Level AC, Output “Hz”)
Model Meters/Second Miles/Hour
03002 / 03101
M = 0.750
Off = 0.2
M = 1.677
Off = 0.4
*When the pulse channel configuration is set to Low Level AC, output “counts”, the
multiplier above is divided by the execution interval in seconds.
7.4.2 Wind Direction
The wind vane is coupled to a 10 k
Ω
potentiometer, which has an 8-degree
electrical dead band between 352 and 360 degrees.
The CR200(X) dataloggers use the ExDelSE() instruction to measure wind
direction. All other CRBasic dataloggers use the BRHalf() instruction.
Some CRBasic measurement sequences can cause the measurement of the
wind direction to return a negative wind direction (–30°) while in the dead
band. To overcome this problem, all program examples use a delay of 20 ms
(20,000 μ s) and set any negative wind direction values to 0.0: If WindDir < 0,
then WindDir = 0.0.
Excitation voltages, range codes, and multipliers for Campbell Scientific
dataloggers are listed in TABLE 7-4 . Appendix D , Wind Direction
Measurement Theory
(p. D-1)
, has additional information on the BRHalf()
measurement instructions.
TABLE 7-4. Parameters for Wind Direction
CR200(X) CR300 Series
CR800,
CR850,
CR1000 CR1000X CR6
CR5000,
CR3000
Measurement Range NA mV2500 mV2500 mV5000 mV1000 mV5000
Excitation Voltage 2500 mV 2500 mV 2500 mV 2500 mV 1000 mV 5000 mV
Reverse Excitation NA NA True True True True
Delay or Settling Time 20000 µs 20000 µs 20000 µs 20000 µs 20000 µs 20000 µs
Multiplier 0.1408 352 352 352 352 352
Offset 0 0 0 0 0 0
7.4.3 Wind Vector Processing Instruction
The Wind Vector output instruction is used to process and store mean wind
speed, unit vector mean wind direction, and standard deviation of the wind
direction (optional) from the measured wind speed and direction values.