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NI 9219 Calibration Procedure
10
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Current Accuracy Verification
Complete the following steps to verify the current accuracy of an NI 9219.
1.
Connect the NI 9219 to the DMM and source as shown in Figure 4.
Figure 4.
Current Accuracy Verification Connections to the NI 9219
2.
Set the current source to the appropriate test point value indicated in Table 9. Use the smallest
available range needed to source each test point. Using a range larger than necessary creates
unwanted additional noise.
3.
Configure the DMM for a current measurement in the lowest appropriate range according to the
test point from Table 9.
4.
Enable Auto Zero on the DMM.
5.
Create an AI current channel on the NI 9219. Configure the channel according to Table 8.
6.
Commit the task.
7.
Acquire a current reading with the DMM. Record this measurement as I
ref
.
8.
Acquire 20 current readings per channel on the NI 9219.
Note
Perform the DMM measurements and the NI 9219 measurements as simultaneously as
possible in order to reduce error from drift in the current source.
9.
Record the average of the readings for the channel you want to verify as I
channel
.
Table 8.
NI 9219 Configuration for Current Accuracy Verification
Measurement
Type
Physical
Channels
Min (A)
Max (A)
ADC Timing
Mode
Sample Timing
Type
Current
ai0:3
–0.025
0.025
High Resolution
On Demand
I+
I–
HI
AMPS
LO
NI 9219
DMM
Source
HI (3)
LO (5)
Ch 0
HI (3)
LO (5)
Ch 1
HI (3)
LO (5)
Ch 2
HI (3)
LO (5)
Ch 3