NI 449
x
Calibration Procedure | © National Instruments | 19
7.
Configure the voltage source to output a constant voltage with the amplitude listed in the
0 dB gain row of Table 20. Measure the actual voltage source value with the digital
multimeter.
8.
Perform the AI DC coupled calibration adjustment by selecting the DAQmx Adjust DSA
AI Calibration With Gain and Coupling VI from the DAQmx Adjust DSA AI Calibration
Polymorphic VI, as shown below. The reference voltage parameter is set to the applied
voltage source amplitude as indicated by the DMM measurement. The gain parameter is set
to the value of the device gain setting being calibrated, where 0, for example, represents
0 dB. The coupling parameter is set to DC.
9.
Repeat steps 7 and 8 for each gain setting that your device supports. Refer to Table 6 for the
gain settings supported by NI 449x devices. When performing step 7, adjust the output of
the voltage source based on the amplitudes in Table 20. When performing step 8, adjust the
gain and reference voltage parameters appropriately.
Table 20.
Voltage Source Output for AI DC Coupled Calibration Adjustment on
NI 4492/4497/4499
Device Gain
Voltage Source Output (Nominal)
Amplitude (V)
0 dB
8.5
10 dB
2.688
20 dB
0.85
30 dB
0.269
LabVIEW Block Diagram
NI-DAQmx Function Call
Call
DAQmxAdjustDSAAICalWithGain
AndCoupling
with the following
parameters:
calHandle
:
myCalHandle
referenceVoltage
: DMM measurement
value
gain
: 0.0
coupling
: DAQmx_Val_DC
