National Instruments PXI-4130, Calibration Procedure, Page: 42 / 44

42 | ni.com | NI PXI-4130 Calibration Procedure
Adjusting Current Measurement Accuracy
To adjust current measurement, configure the calibrator using the
Calibrator Resistance
value
from Table 4, program the NI 4130 according to the values in Table 21, and then compare the
current outputs measured by an external DMM to the measured current reported by the NI 4130.
Connect the NI 4130 channel
x
to the DMM or to the Fluke 5700A/5720A/5730A calibrator, as
illustrated in Figure 3 or Figure 4. Configure the DMM to the mode and range listed for the
corresponding channel and range in Table 4.
When applicable, configure the Fluke 5700/5720A/5730A calibrator to the
Resistance
value for
the corresponding channel and range in Table 4. Enable external sense (4-wire mode) on the
calibrator. Record the resistance value displayed by the calibrator.
Set the Samples to Average property of the NI 4130 to
300
.
Note
When calibrating channel 1, each current limit range requires a unique call to
the niDCPower Cal Adjust Current Measurement VI.
Pass the current values reported by the NI 4130 and the current values calculated from the DMM
voltage measurements to the niDCPower Cal Adjust Current Measurement VI
(
niDCPower_CalAdjustCurrentMeasurement
function) to calculate the new calibration
coefficients. Call this VI or function once per range.
For the 200 μ A, 2 mA, 20 mA, and 200 mA current ranges of channel 1, divide the voltage
measurement you recorded with the DMM by the resistance measurement you recorded from the
calibrator to calculate the output current. For the 1 A current range of channel 0 and the
2 A current range of channel 1, the DMM measures the output current directly. Subtract the
Output
value for the iteration of channel
x
in Table 21 from the output current calculated above
to obtain the output error.
Refer to the
Output
column of Table 21 for the NI 4130 current limit for each iteration.
After applying a new set of configurations to the NI 4130, wait 3 seconds before taking a
measurement with the DMM or the NI 4130.
When you have successfully completed all adjustment tests, close the calibration session with
action
set to
Commit
. Adjustment of the NI 4130 is now complete. Repeat the
Verification
section to reverify the performance of the NI 4130 post-adjustment. After reverification, update
the verification date and temperature by opening a calibration session, and then close the
calibration session with
action
set to
Commit
. If the NI 4110 successfully passes all verification
tests, calibration is complete.
If the device has successfully passed all verification tests, the NI 4130 is within the published
specifications, and adjustment is optional.