Chapter 4
Connecting Signals
4-14
ni.com
Single-Ended Connection Considerations
A single-ended connection is one in which the AI signal of the
NI 6013/6014 is referenced to a common ground that can be shared with
other input signals. The input signal is tied to the positive input of the
PGIA, and the common ground is tied to the negative input of the PGIA
using AISENSE.
When every channel is configured for single-ended input, up to
16 AI 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 3 m (10 ft).
•
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.
NRSE mode is the only single-ended configuration supported on the
NI 6013/6014. The AISENSE connection differs for floating and grounded
signal sources. For floating signal sources, AISENSE is connected directly
to AIGND, and the NI 6013/6014 provides the reference ground point for
the external signal. For grounded signal sources, AISENSE is connected
to the external signal reference ground, preventing current loops and
measurement errors.
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.
