National Instruments VXI-MIO Series Differential Connection Considerations (DIFF Input Configuration)

Chapter 4 Signal Connections
VXI-MIO Series User Manual 4-14  National Instruments Corporation
Differential Connection Considerations (DIFF Input Configuration)
A differential connection is one in which the VXI-MIO Series module
analog input signal has its own reference signal or signal return path.
These connections are available when the selected channel is
configured in DIFF input mode. The input signal is tied to the positive
input of the PGIA, and its reference signal, or return, is tied to the
negative input of the PGIA.
When you configure a channel for differential input, each signal uses
two multiplexer input lines—one for the signal and one for its reference
signal. Therefore, with a differential configuration for every channel,
up to 32 analog input channels are available.
You should use differential input connections for any channel that
meets any of the following conditions:
• The input signal is low level (less than 1 V).
• The leads connecting the signal to the VXI-MIO Series module are
greater than 10 ft (3 m).
• The input signal requires a separate ground-reference point or
return signal.
• The signal leads travel through noisy environments.
DIFF input connections reduce pick-up noise and increase
common-mode noise rejection. Differential signal connections also
allow input signals to float within the common-mode limits of the
PGIA.