Chapter 4
Analog Input
©
National Instruments Corporation
4-33
In the single-ended modes, more electrostatic and magnetic noise co
u
ples
into the signal connections than in differential config
u
rations. The co
u
pling
is the res
u
lt of differences in the signal path. Magnetic co
u
pling is
proportional to the area between the two signal cond
u
ctors. Electrical
co
u
pling is a f
u
nction of how m
u
ch the electric field differs between the
two cond
u
ctors.
With this type of connection, the NI-PGIA rejects both the common-mode
noise in the signal and the gro
u
nd potential difference between the signal
so
u
rce and the device gro
u
nd.
Refer to the
Using Non-Referenced Single-Ended Connections for
Ground-Referenced Signal Sources
section for more information abo
u
t
non-referenced single-ended connections.
When to Use Referenced Single-Ended Connections
with Ground-Referenced Signal Sources
Do
not
u
se referenced single-ended connections with gro
u
nd-referenced
signal so
u
rces. Use non-referenced single-ended or differential
connections instead.
As shown in the bottom-rightmost cell of Table 4-2, there can be a potential
difference between AI GND and the gro
u
nd of the sensor. In referenced
single-ended mode, this gro
u
nd loop ca
u
ses meas
u
rement errors.
