
3.3.3 Common Mode Voltage < +/-10V/Single-Ended Inputs
This is not a recommended configuration. In fact, the phrase common mode has no meaning in a single-ended system and
this case would be better described as a system with offset grounds. Anyway, you are welcome to try this configuration,
no system damage should occur and depending on the overall accuracy you require, you may receive acceptable results.
Figure 3-6.
Common Mode Voltage < +/-10V/Single-Ended Inputs
3.3.4 Common Mode Voltage < +/-10V/Differential Inputs
Systems with varying ground potentials should always be monitored in the differential mode. Care is required to assure
that the sum of the input signal and the ground differential (referred to as the common mode voltage) does not exceed the
common mode range of the A/D board (+/-10V on the CIO-DAS16/F). Figure 3-7 shows recommended connections in
this configuration.
Figure 3-7. Common Mode Voltage < +/-10V/Differential Inputs
15
+
-
Input
Amp
To A/D
A/D Board
I/O
Connector
LL GND
CH Hi
h
CH Low
Signal Source
with Comm on
M ode Voltage
Si
nal source and A/D board
with common mode volta
e
connected to a differential input.
GND
The voltage differential
between these grounds,
added to the maximum
input signal must stay
within +/-10V
S
stem 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.
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