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NI 9219 Calibration Procedure
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© National Instruments Corporation
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15
5.
Scale the data by using the formula below to change the unscaled data into
Ω
.
where
range
max
is the maximum value for the selected range in Table 16.
6.
Perform the following calculation using the recorded
Ω
ref
and
Ω
channel
values.
7.
Compare the calculation result to the Upper Limit and Lower Limit values in Table 16.
Note
The test limits listed in Table 16 are derived using the values in Table 53.
8.
Disconnect the resistor from the device.
9.
Repeat steps 1 through 8 for all test points on the NI 9219.
10. Repeat steps 1 through 9 for all channels on the NI 9219.
4-Wire Resistance Accuracy Verification
Complete the following steps to verify the 4-wire resistance accuracy of an NI 9219.
1.
Connect the NI 9219 to the resistor and the DMM as shown in Figure 6. Connect the sense
leads of the DMM as close as possible to the same point that the sense leads of the NI 9219
(HI and LO) connect to the resistor to ensure that the DMM reference measurements
include the same lead wire resistance as the NI 9219 4-wire measurements.
Table 16.
NI 9219 Verification Test Limits for Quarter-Bridge Accuracy
Mode
Range
Test Point
1–Year Limits
Min
(
Ω
)
Max
(
Ω
)
Location
Value
Lower
Limit (
Ω
)
Upper
Limit (
Ω
)
Quarter-Bridge
350
Ω
0
390
Max
309
Ω
±1%
–0.61
0.61
Min
4.99
Ω
±5%
–0.37
0.37
Quarter-Bridge
120
Ω
0
150
Max
121
Ω
±1%
–0.33
0.33
Min
4.99
Ω
±5%
–0.24
0.24
Ω
channel
data
unscaled
2
24
-------------------------------
range
max
×
=
Accuracy
Ω
channel
Ω
ref
–
=