Advantech MIC-3716, Manual

Page: 48 / 127

38
To avoid the ground loop noise effect caused by common-mode
voltages, you can connect the signal ground to the Low input. Fig. 3-3
shows a differential channel connection between a ground-reference
signal source and an input channel on the MIC-3716. With this
connection, the PGIA rejects a common-mode voltage V
cm
between the
signal source and the MIC-3716 ground, shown as V
cm
in Fig. 3-3 .
Fig. 3-3: Differential input channel connection - ground
reference signal source
If a floating signal source is connected to the differential input channel,
the signal source might exceed the common-mode signal range of the
PGIA, and the PGIA will be saturated with erroneous voltage-readings.
You must therefore reference the signal source against the AIGND.
Fig. 3-4 shows a differential channel connection between a floating