Campbell Scientific 110PV Surface Temperature Probe - Manual (Page 20)

110PV Surface Temperature Probe
BeginProg
Scan (1,Sec,3,0)
' Measure 110PV-L probe
BrHalf (T110PV_mV,1,mV2500,1,Vx1,1,2500,True ,0,_60Hz,1.0,0)
' Convert mV to ohms
T110PV_Res=4990*(1-T110PV_mV)/T110PV_mV
' Subtract off cable resistance (see 110PV-L cable for R_cable)
T110PV_Res= T110PV_Res-R_cable
' Using the Steinhart-Hart equation to convert resistance to temperature
T110PV_Temp_C = (1/(A+B*LOG(T110PV_Res)+C*(LOG(T110PV_Res))^3))-273.15
'Convert Celsius to Fahrenheit
T110PV_Temp_F = T110PV_Temp_C * 1.8 + 32
'Call AvgTemp data table
CallTable AvgTemp
NextScan
EndProg
5.1.1.3 Sample 4-Wire Half BridgeProgram for CR1000
'CR1000 Series Datalogger
'This example program measures a single 110PV-L probe utilizing the
'BRHalf4Winstruction once a second and stores the
'average temperature in degrees C every 10 minutes.
'110PV-L Wiring Configuration
'Lead Color CR1000 Channel Description
'Black ------ VX1/EX1 ------ Voltage Excitation
'Red -------- DIFF1H ------- Signal
'Purple----- DIFF1L-------- Signal Reference
'Blue ------- AG-------------- Signal Reference
'Green ----- DIFF2H ------- Sense +
'White------ DIFF2L-------- Sense -
'Clear ------ AG-------------- Shield
'Declare variables for temperature measurement using Half Bridge configuration
Public T110PV_mV
Public T110PV_Res
Public T110PV_Temp_C
Public T110PV_Temp_F
'Declare constants to be used in Steinhart-Hart equation
Const A=1.129241*10^-3
Const B=2.341077*10^-4
Const C=8.775468*10^-8
'Declare variable units
Units T110PV_mV= millivolts
Units T110PV_Res=Ohms
Units T110PV_Temp_C=Deg C
Units T110PV_Temp_F=Deg F
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