Chapter4 ConnectingSignals
NI6013/6014 User Man ual 4-14 ni.com
Single-Ended Connection Considerations
A single-ended connection is one in which the AI signal of the
NI6 013/6014 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 everychannel is configured for single-ended input, up to
16 AI channels are available.
Youcan use single-ended input connections for any input signal that meets
the followingconditi ons:
•The inputsignal is high level (greater than 1 V).
•Theleads 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.
DIFFinput connections are recommendedfor greater signal integrity
forany input signal that does not meet the preceding conditions.
NRSEm ode is the only single-ended configuration supported on the
NI6 013/6014. The AISENSE connection differs for floating and grounded
signalsources. For floating signal sources, AISENSE is connecteddirectly
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
measurementerrors.
In single-ended configurations,more e lectrostatic and magnetic noise
couples into the signal connections than in differentialc onfigurations.
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 howmuch the electric fielddiffers
between the two conductors.