Campbell Scientific 237-L Leaf Wetness Sensor - Manual (Page 8)

Model 237 Leaf Wetness Sensor
4. Programming Examples
Each example program measures leaf wetness and outputs a sample resistance
and a time fraction the sensor is wet. In these examples, the output interval is
set to 60 minutes, so a time fraction wet of .33 is equivalent to 20 minutes
during that hour. Wetness threshold is set at 150 kΩ.
4.1 CR1000 Program Example
Public Vs_Vx
Public Rs_kOhms
DataTable(Wetness,true,-1)
OpenInterval
DataInterval(0,60,Min,10)
Sample(1, Rs_kOhms, FP2)
Histogram(Rs_kOhms, FP2, 0, 1, 001, 1 , 0, 150) 'Enter threshold in 8th parameter
EndTable
BeginProg
Scan(60,Sec,
3, 0)
BRHalf(Vs_Vx, 1, mV25, 1, VX1, 1, 2500, True, 0, 250, 1, 0)
Rs_kOhms = (1 / Vs_Vx) - 101
CallTable Wetness
NextScan
EndProg
4.2 CR200(X) Programming
'CR200(X) Series Datalogger
Public Vs_Vx
Public Rs_kOhm
Public ScanIntervalWet
Public ScanIntervalSum
Public TimeFractionWet
DataTable (Wetness,1,-1)
DataInterval
(0,60,min) 'Interval must match IfTime interval (below)
Sample (1,Rs_kohm)
Sample (1,TimeFractionWet)
EndTable
BeginProg
Scan
(1,Min)
'Measure
Wetness
ExDelSE(Vs_Vx,1,1,1,mV2500,500,.0004,0)
'Zero measurement when measurement < 0
If Vs_Vx < 0 Then Vs_Vx = 0
Rs_kOhm = (1 / Vs_Vx) - 101
'Sum
Scan Intervals
ScanIntervalSum = ScanIntervalSum + 1
4