Campbell Scientific 4WFBS120, 4WFBS350, 4WFBS1K 4 Wire Full Bridge Terminal Input Modules - Manual (Page 14)

4WFBS120, 4WFBS350, 4WFBS1K 4 Wire Full Bridge Terminal Input Modules (TIM)
Scan (10,mSec,100,0) 'Scan once every 10 mSecs, non-burst
BrFull (StrainMvperV(),3,mV50,4,1,5,7,1,5000,True,True,70,100,1,0)
StrainCalc (Strain(),3,StrainMvperV(),0,-1,GF(),0) 'Strain calculation
CallTable STRAIN
Next Scan 'Loop up for the next scan
SlowSequence 'Slow sequence Scan to perform temperature
Scan (1,Sec,0,0) ' compensation on DAQ
Calibrate 'Corrects ADC offset and gain
BiasComp 'Corrects ADC bias current
Next Scan
EndProg 'Program ends here
Example Program 4.2. CR9000X ¼ bridge Strain with 3 reps and zero offset
This example program starts out with Example Program 4.1 and adds
instructions (highlighted) to perform a zero calibration. As all strain circuits
have a zero or initial imbalance that is related to the circuit rather than the
member undergoing strain, a zero reading is often used to offset or remove this
apparent strain. Again, see the manual and CRBasic editor’s Help file for
more in-depth discussion on the instructions.
The FieldCalStrain instruction takes care of the underlying math for the
zeroing using equation 4.1.2.
The LoadFieldCal instruction facilitates the reloading of the calibration
factors when the logger is powered up. In addition, the programmer should
create a DataTable (we have called this DataTable Calib in the example) to
store the calibration factors each time a calibration is done.
The NewFieldCal is a Boolean flag variable that is only high during the Scan
that a calibration has been completed. It is used in the DataTable instruction’s
trigger parameter to trigger the table to record a record.
The SampleFieldCal output instruction is used to inform the logger to store all
of the calibration factors that are controlled using the FieldCalStrain
instruction.
' Program name: STRAIN0.C9X
Public StrainMvperV(3) : Units StrainMvperV = mV_per_V 'Raw Strain dimensioned source
Public Strain(3) : Units Strain = uStrain ‘uStrain dimensioned source
Public GF(3) 'Dimensioned gauge factor
Public ZeromV_V(3), ZeroStrain(3)
Public ZReps, ZIndex, ModeVar
DataTable (STRAIN,True,-1) 'Trigger, auto size
DataInterval (0,0,0,100) 'Synchronous, 100 lapses, autosize
CardOut (0,-1) 'PC card , size Auto
Sample (3,Strain(),IEEE4) '3 Reps, uStrain, Resolution
Sample (3,StrainMvperV(),IEEE4) ‘3Reps,Stain mVolt/Volt, Resolution
EndTable 'End of table STRAIN
DataTable (Calib, NewFieldCal ,10) ‘Table for calibration factors from zeroing
SampleFieldCal ‘User should collect these to his computer
EndTable ‘for future reference
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