Chapter 3
Configuring Your SCXI Hardware and Software
©
National Instruments Corporation
3-17
a.
Configure the first-stage filtering.
Jumpers W5, W21, W31, and W43 select the first-stage filtering.
Each of these jumpers has two positions—A and B. Position A
selects the first stage of 4 Hz filtering, whereas position B selects
the first stage of 10 kHz filtering.
b.
Configure the second-stage filtering.
Jumpers W6 through W13 select the second-stage filtering, which
you must configure for the same frequency as that of the first
stage. There are actually only four jumpers, as in the first stage;
W6 through W13 correspond to eight positions, rather than
eight jumpers. You can set each jumper to one of two positions.
Setting the jumper to an even number (for example, W6) selects
the second stage of 4 Hz filtering, whereas setting the jumper to
an odd number (for example, W7) sets the second stage of the
same channel to 10 kHz filtering. Refer to Table 3-11 for the
jumper and channel correspondence for filtering.
3.
Configure the excitation mode as current or voltage.
You can configure each SCXI-1121 excitation channel to produce
voltage or current excitation. Strain gauges require voltage excitation,
whereas RTDs and thermistors typically require current excitation.
Each excitation channel has two jumpers to select the appropriate
mode—W14, W15, W22, W23, W34, W35, W46, and W47.
Table 3-12 summarizes the excitation mode jumper settings. Notice
that only position 1 is marked on the SCXI-1121 module. The
factory-default excitation mode for each channel is voltage.
Table 3-11.
SCXI-1121 First-Stage and Second-Stage Filter Jumper Configuration
Input Channel
Number
First-Filter Jumper
Second-Filter Jumper
4 Hz
(Factory-Default)
10 kHz
4 Hz
(Factory-Default)
10 kHz
0
W5-A
W5-B
W6
W7
1
W21-A
W21-B
W8
W9
2
W31-A
W31-B
W10
W11
3
W43-A
W43-B
W12
W13
