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National Instruments Corporation
25
NI 9219 Calibration Procedure
11. Configure DMM2 for a voltage measurement in the 1 V range.
12. Enable Auto Zero on DMM2.
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
.
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 .
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.
Adjustment
Following the adjustment procedure automatically updates the calibration date and temperature in the
EEPROM of the NI 9219.
Note
National Instruments recommends a complete adjustment of your device to renew the
calibration interval. However, if you do not want to perform an adjustment, you can update the
calibration date and onboard calibration temperature without making any adjustments by calling only
DAQmx Initialize External Calibration VI, DAQmx Set Temperature C Series Calibration, and
DAQmx Close External Calibration VI.
Table 23.
NI 9219 Verification Test Limits for Full-Bridge Accuracy
Mode
Range
Test Point
1
–
Year Limits
Min
(mV/V)
Max
(mV/V)
Location
Value
Configuration
Lower Limit
(
V/V)
Upper Limit
(
V/V)
Full-Bridge
62.5 mV/V
–62.5
62.5
Max
1 k
±5%
Configuration 2
–17.6
17.6
Mid
0
Configuration 2
–12.3
12.3
Min
1 k
±5%
Configuration 3
–17.6
17.6
Full-Bridge
7.8 mV/V
–7.8125
7.8125
Max
120
±5%
Configuration 2
–12.6
12.6
Mid
0
Configuration 2
–11.9
11.9
Min
120
±5%
Configuration 3
–12.6
12.6
Ratio
ref
V
DMM
2
V
DMM
1
----------------
=
Accuracy
Ratio
channel
Ratio
ref
–
=
