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NI 9219 Calibration Procedure
j.
Record the DMM2 measurement as V
DMM2
.
k.
Acquire 20 bridge readings with the NI 9219.
Note
Perform the DMM measurements and the NI 9219 measurements as
simultaneously as possible in order to reduce error from drift in the resistors.
l.
Record the average of the readings as Ratio
channel
.
m. Clear the task.
8.
Perform the following calculation using the two DMM measurements.
9.
Perform the following calculation using the recorded Ratio
ref
and Ratio
channel
values.
10. Compare the calculation result to the Upper Limit and Lower Limit values in Table 30.
Note
The test limits listed in Table 30 are derived using the values in Table 53.
11. Repeat steps 6 through 10 for all test points.
12. Repeat steps 1 through 11 for all channels on the NI 9219.
Table 30.
NI 9219 Verification Test Limits for Half-Bridge Accuracy
Mode
Range
Test Point
1
–
Year Limits
Min
(mV/V)
Max
(mV/V)
Location
Value
Ratio
Lower
Limit
(mV/V)
Upper
Limit
(mV/V)
Half-Bridge
500 mV/V
–500
500
Max
Config. 2
0.916
–0.29
0.29
Mid
Config. 3
0.500
–0.20
0.20
Min
Config. 4
0.083
–0.29
0.29
Ratio
ref
V
DMM
2
V
DMM
1
------------------
=
Accuracy
Ratio
channel
1
2
---
+
Ratio
ref
–
=