User`s manual

Figure 5-8. Common Mode Voltage > +/-10V. Differential Input
5.2.6 Isolated Grounds / Single-Ended Inputs
Single-ended inputs can be used to monitor isolated inputs, though the use of the differential mode will
increase you system’s noise immunity. Figure 5-9 below shows the recommended connections is this
configuration.
Figure 5-9. Isolated Grounds / Single-Ended Input
17
System with a Lar
g
e Common Mode Volta
g
e,
Connected to a Differential Input
L
arge common
mode voltage
between signal
source & A/D board
GND
Isolation
Barrier
When the voltage difference
between signal source and
A/D board ground is large
enough so the A/D board’s
common mode range is
exceeded, isolated signal
conditioning must be added.
+
-
Input
Amp
To A /D
A/D Board
I/O
Connector
LL GND
CH High
CH Low
10 K
10K is a recommended value. You may short LL GND to CH Low
instead, but this will reduce your system’s noise immunity.
Isolated Si
g
nal Source
Connected to a Sin
g
le-Ended Input
I/O
Connector
+
-
Input
Amp
To A /D
LL GND
CH IN
A/D Board


Isolated
signal
source