National Instruments NI 660 Series User Manual page 43

Chapter 3 Signal Connections
In Figure 3-10, PFI 10 and PFI 11 are configured as inputs. V
10 and V
one state to another, it induces a small transition in PFI 11 (the victim line).
The magnitude of the transition (or crosstalk) induced in PFI 11 is
proportional to the following:
•
•
•
Crosstalk is most likely to cause measurement errors when the victim line
is at a low voltage. If this crosstalk is 0.5 V or greater, you may get errors
in measurement.
You should not experience crosstalk if the source impedance of the voltage
source driving the victim line is less than 100 Ω. If this source impedance
is larger than 100 Ω and you see crosstalk problems, you should use NI-TIO
filters or a voltage follower with a low output impedance to drive the
victim line.
NI 660x User Manual
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Z
s1
Cable
V
1
Z
s0
V
0
PFI 10
PFI 11
Figure 3-10. Crosstalk Example
drives PFI 11. When PFI 10 (the offending line) transitions from
1
The speed of the transition on the offending line (PFI 10 in the previous
example)
The length of the cable and the proximity of the victim to the offending
line
The source impedance of the victim line (V
and the level of the offending line (V
3-18
PFI 11
Capacitance
PFI 10
drives PFI
0
in the previous example)
1
)
0
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