Table 10. 1 µA Current Output and Measurement Verification
Level
Range
Limit
Range and
Limit
Shunt
Test
Point
As-Found
Measurement Test
Limit (% of C
Offset)
As-Left
Measurement Test
Limit (% of C
Offset)
6 V
1 µA
1 MΩ
-0.9 V
0.022% + 40 pA
0.0071% + 17 pA
0.9 V
1.
Make the necessary connections for this procedure, as shown in the following figure:
Figure 8. Current Connection Diagram, Part 1
Triax Cable
Precision
Shunt
LO
LOS
HI
(T
riax)
HIS
(Banana)
NI-DCPower Device
Sense LO
Sense HI
(Triax)
HI
(Triax)
LO
CHS GND
Shielded Combicon to
Banana/Bare Wire
DMM
Voltage
Mode
+
–
2.
Set the
niDCPower Output Function
property or
NIDCPOWER_OUTPUT_FUNCTION
attribute to DC Voltage for the PXIe-4135.
3.
Set the first specified level range, limit range, and limit on the PXIe-4135.
4.
Measure the internal device temperature and perform self-calibration if necessary.
a)
After measuring the internal device temperature, wait for the internal device
temperature to stabilize. Temperature is considered stable when it has not changed
by more than ±1 °C in the previous 5 minutes.
b)
After the internal temperature has stabilized, if the temperature still exceeds
T
cal
± 1 °C, call the self-calibration VI or function.
5.
Set the level on the PXIe-4135 to the first specified test point.
Complete the following 4 steps within 5 minutes or less of completing the previous step
in order to ensure the internal device temperature remains stable.
6.
Calculate the current through the shunt by completing the following steps.
a)
Take a voltage measurement across the shunt using the DMM.
b)
Divide the voltage measurement by the calibrated value of the shunt.
c)
Record the calculated value as
DMM Measured Current
.
7.
Calculate the lower and upper current measurement test limits using the following
formula:
18
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PXIe-4135 Calibration Procedure
