17
Chapter 3
3.3.2 Differential Input Connections
The differential input channels operate with two signal wires for each
channel, and the voltage difference between both signal wires is mea-
sured. On USB-4711A, when all channels are configured to differential
input, up to 8 analog channels are available.
If one side of the signal source is connected to a local ground, the signal
source is ground-referenced. Therefore, the ground of the signal source
and the ground of the card will not be exactly of the same voltage. The
difference between the ground voltages forms a commonmode voltage
(V
cm
).
To avoid the ground loop noise effect caused by common-mode voltages,
you can connect the signal ground to the
Low
input. Figure 3-3 shows a
differential channel connection between a grounded-reference signal
source and an input channel on USB-4711A. With this connection, the
PGIA rejects a common-mode voltage V
cm
between the signal source and
USB-4711A ground, shown as V
cm
in Figure 3-3.
Note:
In differential input mode, the input channel
n
should be used with
channel
n+1
.
(
n
=0,2,4…14)
Figure 3.3: Differential Input Channel Connection
Summary of Contents for USB-4711A
Page 1: ...USB 4711A 150 kS s 12 bit USB Multifunction Module User Manual...
Page 6: ...USB 4711A User Manual vi...
Page 10: ...USB 4711A User Manual 4...
Page 19: ...13 Chapter3 Figure 3 1 I O Connector Pin Assignment...
Page 26: ...USB 4711A User Manual 20...
Page 27: ...2 APPENDIX A Specifications...
Page 30: ...USB 4711A User Manual 24...