Section 7. Installation
246
Scan
(100,mSec,100,0)
'Measure Bridge Resistance
BrFull
(Raw_mVperV,1,mV50,1,Vx1,1,2500,True ,True ,0,250,1.0,0)
'Calculate Strain for 1/4 Bridge (1 Active Element)
StrainCalc
(microStrain,1,Raw_mVperV,Zero_mVperV,1,GF_Adj,0)
'Steps (1) & (3): Zero Calibration
'Balance bridge and set Zero_Mode = 1 in numeric monitor. Repeat after
'shunt calibration.
FieldCalStrain
(10,Raw_mVperV,1,0,Zero_mVperV,Zero_Mode,0,1,10,0 ,microStrain)
'Step (2) Shunt Calibration
'After zero calibration, and with bridge balanced (zeroed), set
'KnownRes = to gage resistance (resistance of gage at rest), then set
'Shunt_Mode = 1. When Shunt_Mode increments to 3, position shunt resistor
'and set KnownRes = shunt resistance, then set Shunt_Mode = 4.
FieldCalStrain
(13,MicroStrain,1,GF_Adj,0,Shunt_Mode,KnownRes,1,10,GF_Raw,0)
CallTable
CalHist
NextScan
EndProg
7.7.12.6.3
FieldCalStrain() Quarter-Bridge Shunt Example
With CRBasic example FieldCalStrain() Calibration
(p. 245)
sent to the CR3000,
and the strain gage stable, use the CR1000KD Keyboard/Display or software
numeric monitor to change the value in variable KnownRes to the nominal
resistance of the gage, 1000
Ω, as shown in figure
Strain Gage Shunt Calibration
Start
(p. 246).
Set Shunt_Mode to 1 to start the two-point shunt calibration. When
Shunt_Mode increments to 3, the first step is complete.
To complete the calibration, shunt R1 with the 249 kΩ resistor. Set variable
KnownRes to 249000. As shown in figure Strain Gage Shunt Calibration Finish
(p. 247),
set Shunt_Mode to 4. When Shunt_Mode
=
6, shunt calibration is
complete.
FIGURE 62: Strain Gage Shunt
Calibration Start
Summary of Contents for CR3000 Micrologger
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Page 485: ...Section 8 Operation 485 8 11 2 Data Display FIGURE 110 Keyboard and Display Displaying Data ...
Page 487: ...Section 8 Operation 487 FIGURE 112 CR1000KD Real Time Custom ...
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