User`s manual

4.2.2 Common Ground / Differential Inputs
The use of differential inputs to monitor a signal source with a common ground is an acceptable configura-
tion, though it requires more wiring and offers fewer channels than selecting a single-ended configuration.
The diagram below shows the recommended connections in this configuration.
4.2.3 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.
4.2.4 Common Mode Voltage < +/-10V/Differential Inputs
Systems with varying ground potentials should always be monitored in the differential mode. Use care to
ensure 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 (+/-10 V on the PCI-DAS1602/12). The
diagram below shows recommended connections in this configuration.
13
+
-
Input
Amp
To A /D
A/D Board
I/O
Connector
LL GND
CH IN
Signal
Source with
Comm on Gnd
Optional wire
since signal source
and A/D board share
common ground
Signal source and A/D board
sharing common ground connected
to single-ended input.
+
-
Input
Amp
To A/D
A/D Board
I/O
Connector
LL GND
CH High
CH Low
Signal
Source with
Common Gnd
Optional wire
since signal source
and A/D board share
common ground
Required connection
of LL GND to CH Low
Signal source and A/D board
sharing common ground connected
to differential input.