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NI 9219 Calibration Procedure
Figure 5.
Quarter-Bridge Accuracy Verification Connections to the NI 9219
2.
Acquire an
Ω
ref
measurement.
a.
Create an AI voltage channel in the 1 V range on the NI 9219.
b.
Commit the task to place the NI 9219 in voltage mode. This prevents the module from
interfering with the resistance measurements of the DMM.
c.
Configure the DMM for a 4-wire resistance measurement in the appropriate range
according to the appropriate test point from Table 16.
d.
Enable Auto Zero on the DMM.
e.
Acquire a resistance reading with the DMM. Record this measurement as
Ω
ref
.
f.
Clear the task.
3.
Disconnect the DMM from the resistor to ensure that the terminals on the DMM do not
interfere with the resistor while the NI 9219 makes measurements.
4.
Acquire and average samples.
a.
Create an AI bridge (V/V) task on the NI 9219 according to Table 14.
b.
Configure the AI bridge (V/V) task timing according to Table 15.
c.
Start the task.
d.
Acquire 20 unscaled I32 quarter-bridge readings with the NI 9219.
e.
Record the average of the readings as data
unscaled
.
f.
Clear the task.
Table 14.
NI 9219 Configuration for Quarter-Bridge Accuracy Verification
Measurement Type
Minimum
(V/V)
Maximum
(V/V)
Strain Config
Nominal Gage
Resistance
Quarter-Bridge 350
Ω
–0.025
0.025
Quarter-Bridge
350
Quarter-Bridge 120
Ω
120
Table 15.
NI 9219 Timing Configuration
ADC Timing Mode
Sample Timing Type
High Resolution
On Demand
Ω
Ω
S
EN
S
E
HI
LO
HI
LO
R
TestPoint
NI 9219
DMM
HI (3)
LO (5)
Ch
x