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National Instruments Corporation
23
NI 9219 Calibration Procedure
Full-Bridge Accuracy Verification
Complete the following steps to verify the full-bridge accuracy of an NI 9219.
1.
Connect the NI 9219 to DMM1 as shown in Figure 15.
Figure 15.
Full-Bridge Accuracy Verification Connections to the NI 9219 (Configuration 1)
2.
Create an AI bridge V/V channel on the NI 9219. Configure the channel according to Table 22.
3.
Commit the task.
4.
Configure DMM1 for a voltage measurement in the 10 V range.
5.
Enable Auto Zero on DMM1.
6.
Use DMM1 to measure the excitation voltage from the NI 9219. Record this measurement as
V
ExcitationModule
.
Note
The excitation voltage on the NI 9219 may be off if the module is not configured correctly.
The excitation value on the NI 9219 should be at least 2.5 V.
7.
Set the voltage source to V
ExcitationModule
. Use the smallest available range needed to source
V
ExcitationModule
. Using a range larger than necessary creates unwanted additional noise.
8.
Connect the NI 9219 to DMM1, DMM2, and the source as shown in Figures 16 or 17 for the
appropriate test point value indicated in Table . Observe the following conditions when connecting
the equipment to the NI 9219.
•
Connect the leads of DMM1 as close as possible to the terminals on the NI 9219.
•
Connect the HI lead of DMM2 as close as possible to the same point that the HI lead of the
NI 9219 connects to the resistor network.
Table 22.
NI 9219 Configuration for Full-Bridge Accuracy Verification
Measurement
Type
Min (V)
Max (V)
Excitation
Source
Excitation
Value
Bridge
Config
ADC
Timing
Mode
Sample
Timing
Type
Full-Bridge
62.5 mV/V
–0.0625
0.0625
Internal
2.5
Full-Bridge
High
Resolution
On Demand
Full-Bridge
7.8 mV/V
–0.0078125
0.0078125
NI 9219
HI
V
LO
DMM1
EX+ (3)
HI (4)
LO (6)
EX– (5)
Ch
x
