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2.2 Installation Environment and Wiring for LAN Ports
2.2.1 Before Installation and Wiring
Noise resistance of Ethernet
The Ethernet is a network used in offices and buildings, where there is comparatively little
noise. It does not have a higher resistance to noise than ordinary FA application networks.
Caution is required when installing the hub, and when laying cables.
2.2.2 Installation Environment and Noise Control Measures
Measures that can be taken in the installation environm ent
The CPU unit, transceiver, hub, and communication cables should be installed as far as
possible from high-voltage wires, high-voltage equipment, power lines, power equipment,
equipment that generates strong breaker surges, and the wiring for any of this equipment. At
least 100 mm of clearance should be allowed when installing the equipment.
Ethernet LAN
When a device must be installed or a cable must be laid near a noise-generating device for
special reasons, take measures such as:
• install a programmable controller and a hub within a metal panel,
• laying a communication cable inside a metal duct,
• attaching a ferrite core near the CPU unit on the communication cable,
etc.
An alternative measure is to use an optical transceiver close to the noise-generating section
of the equipment and install an optical fiber to keep the noise from affecting nearby
equipment. (This is also effective as a lightning shield for outdoor wiring.)
Metal panels and metal ducts should be grounded at a grounding resistance of 100 Ω or less.
Also, metal panels and metal ducts should be insulated so that they do not come in contact
with communication devices or cables.
2.2 Installation Environment and Wiring for LAN Ports
100mm or more
100mm or more
Noise-generating
device/cable
100mm or more
2-3
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