Measurement Computing PCM-DAS16x/16 - Manual (Page 27)

The following sections depicts recommended input wiring schemes for each of the 8
possible input configuration/grounding combinations.
6.2.1 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 recom-
mend 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. The diagram below shows a recommended connec-
tion diagram for a common ground / single-ended input system.
6.2.2 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. The diagram below shows the recom-
mended connections in this configuration.
23
+
-
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 IN


S ig
n a l
S
o u rc e
w ith
C
o m m
o n G
n d
O p tio nal w ire
since sig na l sou rce
and A /D bo ard sh are
com m o n g round
S ig n a l s o urc e an d A /D b o a rd
s h a rin g c om m o n gro u n d c o n n e c te d
to s in 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 Low


S ig
n a l
S
o urce
w ith
C o m
m o n
G n d
O ptio nal w ire
since signa l source
and A /D bo ard sha re
com m on g round
R equ ired connection
of L L G N D to C H Low
S ign a l s o u rc e an d A /D bo a rd
s ha ring c o m m o n g ro u nd c on n e c te d
to d iffe re n tia l in pu t.