NI PXIe-4154 Calibration Procedure
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© National Instruments Corporation
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25
Adjusting Current Measurement
To adjust the current measurement of a calibrated NI PXIe-4154, compare a range of current test
points measured with an external DMM as a voltmeter in conjunction with a precision shunt to
the measured current reported by the NI PXIe-4154. Refer to Figure 3 or Figure 4 to adjust
current measurement while sourcing. Refer to Figure 5 or Figure 6 to adjust current
measurement while sinking.
Refer to Table 17 for the current test points that you must request and measure with an external
DMM and the NI PXIe-4154 to adjust a given range. For example, the 30 mA on Channel 0
requires the adjustment application to separately request 27 mA, 0 mA, and -27 mA outputs from
the NI PXIe-4154.
For positive currents, the voltage level should be set to the maximum value. Take measurements
with the DMM/precision shunt and the NI PXIe-4154 at each test point. To calculate the current
value using the DMM/precision shunt, divide the voltage measured with the DMM by the
characterized value of the precision shunt.
For negative current adjustment points, an external current source is required to provide the
necessary current. The voltage level for the NI PXIe-4154 should be set to 0 V. Refer to Table 1
for external current source equipment recommendations and requirements.
Note
After requesting a new voltage, wait 3 ms to take a measurement with the
external DMM and NI PXIe-4154 to ensure the system has adequate time to settle
while minimizing self-heating effects of the internal measurement circuitry.
Note
When measuring a 0 A test point, remove any connections to the front panel
I/O connector to ensure no current is flowing through the output.
After test points are measured for a range, call the niDCPower Cal Adjust Current Measurement
VI or the
niDCPower_CalAdjustCurrentMeasurement
function to calculate updated
calibration coefficients. Refer to Table 18 for specific adjustment applications for this VI. Refer
to the
NI DC Power Supplies and SMUs Help
for more information about programming
references common to many VIs within the NI-DCPower API.
Table 17.
NI PXIe-4154 Current Measurement Adjustment Points
Channel
I Range
Required Adjustment Points
Precision Shunt Value
0
30 mA
-27 mA
0 mA
27 mA
100
Ω
0
3 A
-2 A
0 A
2 A
100 m
Ω
1
1.5 A
0 A
0.75 A
1.35 A
100 m
Ω
