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If your application requires nonreferenced inputs, consider using an SCC-AI Series
Note
module as the first stage in a dual-stage configuration.
Using the SCC-FV01
Scaling Voltage Measurements
Measuring Frequencies Below 5 Hz
Calibrating Offset Errors
SCC-FV01 Frequency Input Module User Guide
For information about how to configure the SCC-FV01 module using
NI-DAQmx, refer to the SCC Quick Start Guide.
If you configured the SCC-FV01 using Measurement & Automation
Explorer (MAX) and you are using NI-DAQ, the reading you get from the
E Series DAQ device is properly scaled. Otherwise, you must scale your
readings by multiplying the measured DC voltage by 10 to get the input
frequency in hertz.
The output ripple of the SCC-FV01 increases as the input frequency
decreases, and it is significant for frequencies below 5 Hz. To overcome the
effect of output ripple, acquire and average at least 100 samples per period
for two periods of the input frequency. This gives you more accurate
measurements of frequencies below 5 Hz with the exception of 0 Hz.
At 0 Hz there is no ripple; therefore, there is no special need to acquire
and average your data.
The SCC-FV01 module is calibrated at the factory before shipment. If you
want to adjust for any errors in your system, you need a function generator
and an oscilloscope capable of measuring the frequency you are applying.
The oscilloscope must be several times more accurate than the SCC-FV01
itself.
To adjust the SCC-FV01 module, complete the following steps:
1.
Connect the function generator and oscilloscope to the input of the
specific SCC-FV01 channel you are calibrating.
2.
Adjust the function generator to output the maximum frequency and
amplitude you are measuring.
3.
Using your software, have the E Series DAQ device read the
SCC-FV01 channel.
4.
Adjust the potentiometer on top of the SCC-FV01 module that
corresponds to the channel you are calibrating. Turn the potentiometer
until your software measures the same frequency as that measured by
the oscilloscope at the input.
4
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