National Instruments Module SCXI-1125 - Manual (Page 19)

Chapter 2 Connecting Signals
SCXI-1125 User Manual 2-2 ni.com
completely isolated from other channels. You can operate with
common-mode voltage levels up to 300 V
rms
.
Figures 2-1 through 2-4 show signal connection methods that give the
highest noise immunity.
Ground-Referenced Signal
When the negative input signal line is connected either directly or
indirectly to earth ground (usually at the transducer end), connect this line
to the negative input terminal, as shown in Figure 2-1. No ground
connection is made at the SCXI-1125. This situation includes cases where
a floating source can be riding on a high common-mode voltage that is
ground referenced.
Figure 2-1. Connecting a Ground-Referenced Signal
Module
+
–
+
+
+
–
–
I
High
CMV
V
out V
s
V
cm