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National Instruments Corporation
9
NI PXIe-6672 Calibration Procedure
If the measured value is within the low-limit and high-limit range listed
under the
Acceptable Frequency Range
, the board is calibrated correctly.
Adjustment
If the accuracy of the 10 MHz oscillator is outside the specified range for
the product, the device is out of calibration. A programmable voltage
controls the oscillator frequency. By varying this voltage and precisely
measuring the frequency, you can find a voltage that gives a frequency as
close as possible to 10 MHz.
1.
Complete steps a–c to set the oscillator control voltage. The range
of acceptable voltage values is 0.0 V to 4.095 V with frequency
increasing as voltage increases. Use a control voltage of 2.0475 V,
which is in the middle of the valid range, as a starting point.
a.
Call niSync Initialize VI to set up a handle for the device.
Table 1.
Acceptable Frequency Ranges
Device
Specified
Accuracy
Acceptable Frequency Range
Low Limit
High Limit
NI PXIe-6672
(TCXO)
±2.5 ppm
9,999,975 Hz
10,000,025 Hz
LabVIEW Block Diagram
NI-SYNC C Function Call
Call
niSync_init
with the following
parameters:
resourceName
:
Dev1
idQuery
:
NULL
resetDevice
:
VI_FALSE
vi
: *
SessionHandle
