Measurement Computing CIO-DAS160x/1x - Manual (Page 20)

Figure 5-8. Common Mode Voltage > +/-10V. Differential Input
5.2.6 Isolated Grounds / Single-Ended Inputs
Single-ended inputs can be used to monitor isolated inputs, though the use of the differential mode will
increase you system’s noise immunity. Figure 5-9 below shows the recommended connections is this
configuration.
Figure 5-9. Isolated Grounds / Single-Ended Input
16
S yste m w ith a L a rg e C o m m o n M o d e Vo lta g e,
C o n n e cte d to a D iffe re n tia l In p u t
L arge c
om m on
m
ode v oltage
bet
w een s
ignal
s
ource &
A /D boar
d
G N D
Iso latio n
B arrie r
W hen the voltage difference
betw een signal source and
A /D board ground is large
enough so the A /D board’s
com m on m ode range is
exceeded, isolated signal
conditioning m ust be added.
+
-
In p u t
A m p
To A /D
A /D B o a rd I/O
C o nn ec tor
LL G N D
C H H igh
C H Low
1 0 K
1 0 K is a re c o m m e n d e d v a lu e . Yo u m a y s h o rt L L G N D to C H L ow
in s te ad , b ut th is w ill re d u c e y o u r s y s tem ’s n o ise im m u nity.
Iso lated S ignal S ource
C onne cte d to a S ingle-E nded Input
I/O
C o nn ector
+
-
Inp ut
A m p
To A /D
LL GN D
C H IN
A /D B o a rd
Iso lat
ed
sig na
l
sour
ce