National Instruments 9219, Calibration Procedure

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NI 9219 Calibration Procedure 22 ni.com
13. Acquire voltage measurements with both DMMs. Perform the following calculation using the two
DMM measurements.
14. Acquire 20 bridge readings with the NI 9219. Record the average of the readings as Ratio
channel
.
Note Perform the DMM measurements and the NI 9219 measurements as simultaneously as
possible in order to reduce error from drift in the resistors.
15. Perform the following calculation using the recorded Ratio
ref
and Ratio
channel
values.
16. Compare the calculation result to the Upper Limit and Lower Limit values in Table 21.
17. Clear the acquisition.
18. Repeat steps 8 through 17 for all test points.
19. Repeat steps 1 through 18 for all channels on the NI 9219. NI recommends that you verify each
channel, but you can save time by verifying only the channels used in your application.
20. Disconnect the DMMs and the resistors from the device.
Table 21. 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 Configuration 2 0.916 –0.29 0.29
Mid Configuration 3 0.500 –0.20 0.20
Min Configuration 4 0.083 –0.29 0.29
Ratio
ref
V
DMM 2
V
DMM 1
---------------- =
Accuracy Ratio
channel
1
2
--- +
 
 
Ratio
ref
– =