Floating Signal; Figure 2-2. Connecting A Floating Signal - National Instruments Module SCXI-1125 User Manual

Floating Signal

© National Instruments Corporation
In cases where both signal lines at the transducer end are floating and no
common-mode voltage exists, establish an earth connection at the
SCXI-1125 by connecting the negative input line to chassis ground in the
terminal block, as shown in Figure 2-2. This eliminates noise that can ride
on the floating signal. If the floating signal is not configured like
Figure 2-2, the noise can couple to the chassis ground through the amplifier
and exhibit a differential mode signal that can be amplified by the
amplifier. Connecting the signal to chassis ground breaks the isolation
barrier.
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Figure 2-2. Connecting a Floating Signal

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Chapter 2 Connecting Signals
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SCXI-1125 User Manual