GE 90-30 PLC Series Installation And Hardware Manual page 173

I/O Module Wire Routing
To reduce noise coupling among PLC wires, it is recommended you keep electrically noisy wiring,
such as AC power wiring and Discrete Output Module wiring, physically separated from low-level
signal wiring such as connections to DC and Analog Input modules. This can be accomplished by
grouping separately, where practical, the following categories of wiring:
Grouping Modules to Keep Wires Segregated
If practical, grouping similar modules together in the PLC racks can help keep wiring segregated.
For example, one rack could contain only AC modules and a different rack only DC modules, with
further grouping in each rack by input and output types. For smaller systems, as an example, the
left end of a rack could contain Analog modules, the middle could contain DC modules, and the
right end could contain AC modules. Where AC or Output wiring bundles must pass near low-
level signal wiring bundles, avoid running them beside each other. Route them so that, if they have
to cross, they do so at a right angle. This will minimize coupling between them.
GFK-0356Q Chapter 7 Input/Output Modules
AC power wiring. This includes the AC input to the PLC power supply, as well as other AC
devices in the control cabinet.
Analog Input and Output Module wiring. This should also be shielded to further reduce
noise coupling.
Discrete Output Module wiring. These often switch inductive loads that produce noise
spikes when switched off.
DC Input Module wiring. Although suppressed internally, these low-level inputs should be
further protected against noise coupling by observing these wiring practices.
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