Chapter 4
Signal Connections
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National Instruments Corporation
4-15
Single-Ended Connection Considerations
A single-ended connection is one in which the device analog input signal is
referenced to a ground that can be shared with other input signals. The input
signal is tied to the positive input of the PGIA, and the ground is tied to the
negative input of the PGIA.
When every channel is configured for single-ended input, up to 16 analog
input channels are available.
You can use single-ended input connections for any input signal that meets
the following conditions:
•
The input signal is high level (greater than 1 V).
•
The leads connecting the signal to the device are less than 10 ft (3 m).
•
The input signal can share a common reference point with other
signals.
DIFF input connections are recommended for greater signal integrity for
any input signal that does not meet the preceding conditions.
Using your software, you can configure the channels for two different types
of single-ended connections—RSE configuration and NRSE configuration.
The RSE configuration is used for floating signal sources; in this case, the
device provides the reference ground point for the external signal. The
NRSE input configuration is used for ground-referenced signal sources; in
this case, the external signal supplies its own reference ground point and the
device should not supply one.
In single-ended configurations, more electrostatic and magnetic noise
couples into the signal connections than in differential configurations. The
coupling is the result of differences in the signal path. Magnetic coupling
is proportional to the area between the two signal conductors. Electrical
coupling is a function of how much the electric field differs between the
two conductors.
