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Chapter 4
Analog Input
When to Use Non-Referenced Single-Ended (NRSE) Connections with
Ground-Referenced Signal Sources
When to Use Referenced Single-Ended (RSE) Connections with
Ground-Referenced Signal Sources
M Series User Manual
Only use non-referenced single-ended input connections if the input signal
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.
In the single-ended modes, more electrostatic and magnetic noise couples
into the signal connections than in DIFF 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.
With this type of connection, the NI-PGIA rejects both the common-mode
noise in the signal and the ground potential difference between the signal
source and the device ground.
Refer to the
Using Non-Referenced Single-Ended (NRSE) Connections for
Ground-Referenced Signal Sources
NRSE connections.
Do not use RSE connections with ground-referenced signal sources. Use
NRSE or DIFF connections instead.
As shown in the bottom-rightmost cell of Table 4-6, there can be a potential
difference between AI GND and the ground of the sensor. In RSE mode,
this ground loop causes measurement errors.
section for more information about
4-22
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