NI PXI-4110 Calibration Procedure
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© National Instruments
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29
Adjusting Current Measurement Accuracy
To adjust current measurement, program the NI 4110 to the values in the
Output
column and
configure the external load using the
Equivalent Resistance
value for the iteration of channel
x
in Table 20, and then compare the current outputs measured by an external DMM to the
measured current reported by the NI 4110. Refer to Figure 3 for the necessary connections.
When taking measurements with the NI 4110, set the Samples to Average property to
300
.
Note
To facilitate an accurate measurement using an
Output
value of 0, verify that
the DMM and the external load are disconnected from the NI 4110. For all other
Output
values, the DMM and the external load are connected to the NI 4110.
Use the niDCPower Cal Adjust Current Measurement VI (
niDCPower_
CalAdjustCurrentMeasurement
function) to calculate the new calibration coefficients.
Pass the current values reported by the NI 4110 to the Reported Outputs input of the VI, and pass
the voltage values measured by the DMM to the Measured Outputs input of the VI. Call this VI
or function once per range.
After you successfully complete all adjustment tests, close the calibration session by setting
action
to
Commit
on the niDCPower Close External Calibration VI
(
niDCPower_Close_External_Calibration
function). Adjustment of the NI 4110 is
now complete. Repeat the
section to reverify the performance of the NI 4110
Table 20.
NI 4110 Output Parameters for Current Measurement
Accuracy Adjustment
Channel(s)
Current
Range
Iteration
Equivalent
Resistance (
Ω
)
Output (V)
*
0
1 A
1
open
0
†
2
5
1.875
3
5
3.75
1, 2
1 A
1
open
0
†
2
20
±7.5
3
20
±15
1, 2
20 mA
1
open
0
†
2
1,000
±10
3
1,000
±20
* When adjusting channel 1, the
Output
is positive. When adjusting channel 2, the
Output
is negative.
†
To facilitate an accurate measurement using an
Output
value of 0, verify that the DMM and the external
load are disconnected from the NI 4110. For all other
Output
values, the DMM and the external load are
connected to the NI 4110.
