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8.
Calculate the lower and upper current measurement test limits using the following
formula: Current Measurement Test Limits = DMM Measured Current ± (|DMM
Measured Current| * % of C Offset ).
9.
Disconnect the DMM. Leave the NI 4138 output on.
Figure 6.
Current Connection Diagram, Part 2
Sense LO
Sense HI
HI
LO
Precision
Shunt
NI-DCPower Device
10. Take a current measurement using the NI 4138.
11. Record the value from the previous step.
12. Verify that the recorded NI 4138 value falls within the test limits.
13. Repeat the previous steps, from setting the level to the test point on the NI 4138 up to this
step, for each specified test point in the level range.
14. If more than one level range is specified, repeat the previous steps using the values
specified in each level range.
Verifying
100 μ
A to 100 mA Current Measurement and Output
Compare a set of currents measured by an external DMM to the current test points requested
by the NI 4138.
Complete this procedure only after successfully completing all previous verification
procedures. Verify ranges in the specified order.
Refer to the following table as you complete the following steps.
Table 7.
100 µA to 100 mA Current Output and Measurement Verification
Level Range
Limit
Range and
Limit
Test Point
As-Found
Measurement Test
Limit (% of C
Offset)
As-Left Measurement
Test Limit (% of
C Offset)
100 µA
6 V
-100 µA
0.03% + 12 nA
0.013% + 1.5 nA
100 µA
12
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NI PXIe-4138 Calibration Procedure