3.2.5 Common Mode Voltage > +/-10V
The CIO-DAS08-PGx will not directly monitor signals with common mode voltages greater than +/-10V. You will either need to
alter the system ground configuration to reduce the overall common mode voltage, or add isolated signal conditioning between the
source and your board. See Figures 3-7 and 3-8.
Figure 3-7. Common Mode Voltage - >+/- 10V Single-Ended Input
Figure 3-8. Common Mode Voltage - >+/- 10V Differential Input
11
System with a Lar
e Common Mode Volta
e,
Connected to a Sin
le-Ended Input
I/O
Connector
+
-
Input
Amp
To A/D
LL GND
CH IN
A/D Board
L
arge common
mode voltage
between signal
source & A/D board
GND
Isolation
Barrier
When the volta
e difference
between si
nal source and
A/D board
round is lar
e
enou
h so the A/D board’s
common mode ran
e is
exceeded, isolated si
nal
conditionin
must be added.
S
stem with a Lar
e Common Mode Volta
e,
Connected to a Differential Input
L
arge common
mode voltage
between signal
source & A/D board
GND
Isolation
Barrier
When the volta
e difference
between si
nal source and
A/D board
round is lar
e
enou
h so the A/D board’s
common mode ran
e is
exceeded, isolated si
nal
conditionin
must be added.
+
-
Input
Amp
To A/D
A/D Board
I/O
Connector
LL GND
CH Hi
h
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.
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