Advantech PCI-1713U, User Manual

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PCI-1713U User Manual 16
Figure 3.4: Differential Input Ch. - Floating
If a floating signal source is connected to the differential input channel,
the signal source may 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 to the AIGND.
Figure 3-4 shows a differential channel connection between a floating
signal source and an input channel on the PCI-1713U card. In this figure,
each side of the floating signal source is connected through a resistor to
the AIGND. This connection can reject the common-mode voltage
between the signal source and the PCI-1713U card ground.