©
National Instruments Corporation
11
NI 9219 Calibration Procedure
10. Perform the following calculation using the recorded I
ref
and I
channel
values.
11. Compare the calculation result to the Upper Limit and Lower Limit values in Table 9.
12. Repeat steps 9 through 11 for each channel you want to verify. NI recommends that you verify each
channel, but you can save time by verifying only the channels used in your application.
13. Set the source to zero and clear the acquisition.
14. Repeat steps 2 through 13 for all test points listed in Table 9. NI recommends that you verify the
values for all the iterations listed in Table 9, but you can save time by verifying only the values used
in your application.
15. Disconnect the source and the DMM from the device.
2-Wire Resistance Accuracy Verification
Complete the following steps to verify the 2-wire resistance accuracy of an NI 9219.
1.
Connect the NI 9219 to the resistor and the DMM as shown in Figure 5. Connect the leads of the
DMM as close as possible to the terminals on the NI 9219 to ensure that the DMM reference
measurements include the same lead wire resistance as the NI 9219 2-wire measurement.
Figure 5.
2-Wire Resistance Accuracy Verification Connections to the NI 9219
2.
Create an AI voltage channel in the 1 V range on the NI 9219.
3.
Commit the task to place the NI 9219 in voltage mode. This prevents the module from interfering
with the resistance measurements of the DMM.
4.
Configure the DMM for a 4-wire resistance measurement in the appropriate range according to the
appropriate test point from Table 11.
5.
Enable Auto Zero on the DMM.
6.
Acquire a resistance reading with the DMM. Record this measurement as
ref
.
Table 9.
NI 9219 Verification Test Limits for Current Accuracy
Range
Test Point
1
–
Year Limits
Minimum (mA)
Maximum (mA)
Location
Value (mA)
Lower Limit (mA)
Upper Limit (mA)
–25
25
Max
19.0
–0.02089
0.02089
Mid
0.0
–0.00061
0.00061
Min
–19.0
–0.02089
0.02089
Accuracy
I
channel
I
ref
–
=
Ω
Ω
SENSE
HI
LO
HI
LO
R
TestPoint
NI 9219
DMM
HI (3)
LO (5)
Ch
x