Chapter 3
Configuring Your SCXI Hardware and Software
3-6
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Position W2, the factory-default position, disables filtering. Position
W3 selects the 10 kHz lowpass filter, which filters out signal
components with frequencies above 10 kHz. Position W4 selects
the 4 Hz lowpass filter, which filters out signal components with
frequencies greater than 4 Hz, such as 60 Hz noise. For more
information, refer to the Noise and Filtering section in Chapter 4,
Connecting and Using Accessories and Transducers
Caution
If you enable filtering, you cannot scan SCXI-1100 channels at high rates.
Because the filter is applied after the signal is multiplexed, the sample rate or channel
rate must be low enough for the filter to settle to the required accuracy. Table 3-2 shows
the maximum recommended aggregate sampling rates for settling under worst-case
conditions.
3.
Configure the PGIA output referencing mode.
You use jumper W10 to select the output referencing mode of the
SCXI-1100 PGIA. The correct output referencing mode depends on
the input mode of the DAQ device. Table 3-3 shows three
configurations for jumper W10.
Table 3-2.
SCXI-1100 Filtering Jumper Configuration
Jumper
Description
Configuration
W2—Full bandwidth; no filtering
(factory-default position).
W3—10 kHz lowpass filter; maximum
aggregate sampling rate is 6.7 kS/s.
W4—4 Hz lowpass filter; maximum
aggregate sampling rate is 2.9 S/s.
W2 W3 W4
W2 W3 W4
W2 W3 W4
W2 W3 W4