Measurement Computing CIO-DAS6402/12 - Manual (Page 15)

4.2.1 COMMON GROUND / SINGLE-ENDED INPUTS
Single-ended is the recommended configuration for common ground connections. However, if some of your inputs are common
ground and some are not, we recommend you use the differential mode. There is no performance penalty (other than loss of
channels) for using a differential input to measure a common ground signal source. However the reverse is not true. Figure 4-4
below shows a recommended connection diagram for a common ground / single-ended input system
Figure 4-4. Common Ground / Single-Ended Inputs
4.2.2 COMMON GROUND / DIFFERENTIAL INPUTS
The use of differential inputs to monitor a signal source with a common ground is a acceptable configuration though it requires
more wiring and offers fewer channels than selecting a single-ended configuration. Figure 4-5 below shows the recommended
connections in this configuration.
Figure 4-5. Common Ground / Differential Inputs
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
11
+
-
Input
A m p
To A /D
A /D B o a rd
I/O
C onnector
LL G N D
C H IN
S ig n
a l
S
o urce
w ith
C o
m m o n
G n d
O p tio nal w ire
since signa l sou rce
and A /D bo ard sh are
com m on g round
S ign a l s o u rc e an d A /D b o a rd
s ha ring c om m o n gro u n d c on n e cte d
to sin g le -en d ed inp u t.
+
-
In p u t
A m p
To A /D
A /D B o a rd I/O
C o n n e c to r
LL G N D
C H H igh
C H L ow
S ig n
a l
S
ource
w ith
C o
m m o n
G n d
O p tio nal w ire
since signa l sou rce
and A /D bo ard sha re
com m o n g round
R equ ired connection
of L L G N D to C H Low
S ign a l so urce an d A /D bo a rd
s ha ring co m m o n gro u n d c on n e cte d
to d iffe re ntia l in pu t.