Measurement Computing CIO-DAS16 - Manual (Page 20)

3.3.5 Common Mode Voltage > +/-10V
The CIO-DAS16/F will not directly monitor signals with common mode voltages greater than +/-10V. You will either
need to alter the system ground configuration to reduce the overall common mode voltage, or add isolated signal
conditioning between the source and your board (Figure 3-8).
Figure 3-8. Common Mode Voltage > +/-10V - Differential Input
3.3.6 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 3-9 shows the recommended connections is this configuration.
Figure 3-9. Isolated Grounds / Single-Ended Inputs
16
System w ith a La rge C o m m on M ode Vo ltag e,
C o nne cte d to a D iffe rential Inp ut
L arge co
m m on
m
ode vo
ltage
be
tween
signa
l
sour
ce & A/D b
oard
G N D
Iso la tio n
B a rrie r
W hen the voltage difference
between sig nal source and
A/D board g round is large
enough so the A/D boa rd’s
com m on m ode range is
exceeded, isolated sig nal
conditioning m ust be added.
+
-
Inp ut
A m p
To A /D
A /D B o a rd I/O
C o nn ecto r
LL GN D
CH H igh
CH Low
1 0 K
1 0K is a reco m m e nd ed va lu e. You m ay sh ort LL G N D to C H L ow
in s te ad , b u t this w ill re du c e yo ur s ystem ’s n o ise im m u nity.
Iso late d S ignal S ou rce
C on ne cte d to a S in gle-E nd ed In pu t
I/O
C o nn ector
+
-
Inp ut
A m p
To A /D
L L G N D
C H IN
A /D B o a rd
Is o la t
ed
s ig n a
l
s
ou rc e