Campbell CR3000 Micrologger, Руководство оператора

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Section 7. Installation
280
CRBasic Programs and Notes
PT100 BrHalf4W() Four-Wire Half-Bridge Calibration
'This program example demonstrates the calibration of a 100-ohm PRT (PT100) in a four-wire
'half bridge with voltage excitation. See adjacent procedure and schematic.
'Declare constants and variables:
Const Rf = 100000 'Value of bridge resistor
Public X 'Raw output from the bridge
Public RS0 'Calculated PT100 resistance at 0 °C
BeginProg
Scan (1,Sec,0,0)
....'Measure X:
'BrHalf4W(Dest,Reps,Range1,Range2,DiffChan,ExChan,MeasPEx,ExmV,RevEx,RevDiff,
' SettlingTime,Integ,Mult,Offset)
BrHalf4W (X,1,mV50,mV50,1,Vx1,1,4160,True,True,0,250,1,0)
'Calculate RS0:
RS0 = X * Rf
NextScan
EndProg
PT100 BrHalf4W() Four-Wire Half-Bridge Measurement
'This program example demonstrates the measurement of a 100-ohm PRT in a four-wire
'half bridge using current excitation. See previous procedure and schematic.
'Declare constants and variables:
Const Rf = 100000 'Value of bridge resistor
Const RS0 = 100000 'Resistance of PT100 at 0 °C from calibration program
Public X 'Raw output from the bridge
Public RS 'Calculated PT100 resistance
Public RS_RS0 'Calculated ratio of RS/RS0
Public DegC 'Calculated temperature
BeginProg
Scan (1,Sec,0,0)
....'Measure X:
'BrHalf4W(Dest,Reps,Range1,Range2,DiffChan,ExChan,MeasPEx,ExmV,RevEx,RevDiff,
' SettlingTime,Integ,Mult,Offset)
BrHalf4W (X,1,mV50,mV50,1,Vx1,1,4160,True,True,0,250,1,0)
'Calculate RS and RS/RS0:
RS = X * Rf
RS_RS0 = RS/RS0
....'Calculate temperature from RS_RS0:
'PRTCalc(Dest,Reps,Source,PRTType,Mult,Offset)
PRTCalc (DegC,1,RS_RS0,1,1.0,0)
NextScan
EndProg