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National Instruments Corporation
D-1
SC-2345/2350 Carrier User Manual
D
Common Questions
Which power option should I use for my application?
Refer to Appendix C,
SCC Power Requirements and Solutions
,
to
determine which option to use
.
I am sampling a very-low-voltage, noisy signal. How should I condition
the signal?
If the signal is within the ±50 mV range, use an SCC-AI07 isolated analog
input module. If the signal is of higher amplitude, but still within the
±100 mV range, use an SCC-AI06. Each of these modules has a 10 kHz
lowpass filter. The SCC-AI07 applies a gain of 200, and the SCC-AI06
applies a gain of 100.
Why should I amplify a noisy, low-amplitude analog signal using an
SCC module? Can’t I just amplify it using my E/M Series DAQ device?
One reason to amplify low-level signals close to the signal source instead
of at the E/M Series DAQ device is to increase the signal-to-noise ratio. If
you use the E/M Series DAQ device to amplify the signal, the E/M Series
DAQ device also measures and digitizes any noise that enters the lead wires
along the signal path. However, if you amplify the signal closer to the signal
source, the ratio of signal voltage to noise voltage that enters the lead wires
is larger. Therefore, the noise has a less destructive effect on the signal.
I need to sample a 24 V signal. Which SCC module(s) should I use?
Use an SCC-AI01 isolated analog input module. The SCC-AI01 has an
input range of ±42 V and applies a gain of 0.2, yielding a signal of ±8.4 V.
This produces a signal within the input range of the E/M Series DAQ
device.