Omron NX-PA Series User Manual page 133

• Never bundle output signal lines with high-voltage or power lines, and do not route them in close
proximity or parallel to such lines.
If output signal lines must be routed in close proximity to such lines, place them in separate ducts or
conduits. Be sure to ground the ducts or conduits.
I/O cables
Power lines
Suspended ducts
• If the signal lines and power lines cannot be routed in separate ducts, use shielded cable. Connect
the shield to the ground terminal at the Controller, and leave it unconnected at the input device.
• Wire the lines so that common impedance does not occur.
Such wiring will increase the number of wires, so use common return circuits.
Use thick wires with sufficient allowance for the return circuits, and bundle them with lines of the
same signal level.
• For long I/O lines, wire the input and output signal lines separately.
• Use twisted-pair wires for pilot lamps (and particularly lamps with filaments).
• Use countermeasures, such as CR surge absorbers and diodes, for input device and output load
device noise sources, as required.
External Wiring
Wiring, and noise countermeasures in particular, are based on experience, and it is necessary to
closely manage wiring based on experience and information in the manuals.
 Wiring Routes
Each of the following combinations includes different signal types, properties, or levels. They will
cause the signal-to-noise ratio to drop due to factors such as electrical induction. As a general rule
when wiring, either use separate cables or separate wiring routes for these items. Future mainte-
nance operations and changes to the system will also be made easier by carefully organizing the
wiring from the start.
• Power lines and signal lines
• Input signals and output signals
• Analog signals and digital signals
• High-level signals and low-level signals
• Communications lines and power lines
• DC signals and AC signals
• High-frequency devices (such as Inverters) and signal lines (communications)
NX-series CPU Unit Hardware User's Manual (W535)
I/O cables Power lines
I/O cables
Floor ducts
I/O Cable Arrangement
4 Installation and Wiring
Power lines
Conduits
4
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