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Table 5.
Current Offset Verification
Level
Range
Limit
Range and
Limit
Test
Point
As-Found Offset Test
Limit
As-Left Offset Test Limit
Lower Limit
Upper
Limit
Lower Limit
Upper
Limit
600 mV
1 μA
0 mV
-200 pA
200 pA
-25 pA
25 pA
10 µA
-1.4 nA
1.4 nA
-200 pA
200 pA
100 µA
-12 nA
12 nA
-1.5 nA
1.5 nA
1 mA
-120 nA
120 nA
-15 nA
15 nA
10 mA
-1.2 μA
1.2 μA
-150 nA
150 nA
100 mA
-12 μA
12 μA
-1.5 μA
1.5 μA
1 A
-120 μA
120 μA
-15 μA
15 μA
3 A
-1.8 mA
1.8 mA
-500 μA
500 μA
1.
Disconnect all equipment from the output of the NI 4138.
2.
Measure the internal device temperature and perform self-calibration if necessary.
a)
If the internal device temperature exceeds T
cal
± 1 °C, wait up to 5 minutes for the
temperature to stabilize to within T
cal
± 1 °C.
b)
If after 5 minutes the stable temperature still exceeds T
cal
± 1 °C, call the self-
calibration VI or function.
3.
Take a current measurement using the NI 4138.
4.
Record the value from the previous step.
5.
Verify that the recorded value falls within the test limits.
6.
If more than one limit range is specified, repeat the previous steps using the values
specified in each limit range.
Verifying
1 μ
A and
10 μ
A Current Measurement and Output
Compare a set of measured currents reported by the NI 4138 to the currents measured by an
external DMM.
Complete this procedure only after successfully completing all previous verification
procedures. Verify ranges in the specified order.
1.
Refer to the following table as you complete the following steps.
10
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NI PXIe-4138 Calibration Procedure