Installation guide

Network Infrastructure for EtherNet/IP™
Designing the Infrastructure
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4.5.1.2 Plenum-rated Cables
Plenum installations require special material compounds in the makeup of cables. If an application
requires cables to be run in air-handling space, plenum-rated cables should be used, and may be required
by local electrical codes. (Often local electrical codes are concerned with voltage and current levels for
power wiring in a heated duct.) Another cautionary note: Many air-handling ducts have sharp edges of
sheet metal throughout—especially at joints and corners, which can easily cut cable when it is pulled
through existing duct work.
4.5.1.3 Weld Splatter-Proof Cables
If an application requires control of welding equipment, cables should be routed to reduce damage from
weld splatter and noise ingress. All cables should be routed to cross over welding and motor control
cables at right angles and should never run parallel to control cables. The cables should be protected from
weld splatter either by adding protective sheath, using conduit, or selecting cables with the proper jacket
insulation.
4.5.1.4 High Flex
Typically, Ethernet cables are constructed of 24-gauge solid copper conductors, which are not suited to
constantly moving machinery, such as robots. High-flex applications require stranded-type conductor
construction to extend the life of a cable in flexing applications. Also note that high-flex cables are rated
differently based on the type of flexing to which they will be exposed. Trailing cable or “C Track”
applications require different cables than applications where cables are exposed to a continuous back and
forth, or “tick-tock” type of flexing. Other technologies that can replace wiring in these applications
include wireless and infra-red (IR) communications.
4.5.1.5 Ambient Temperature
The ambient temperature of the environment must be considered in specifying the cables and connectors
to be installed. Some Ethernet cables cannot survive or will not perform to specification in the extreme
hot and cold temperatures of some industrial environments.
4.6 Performance Considerations: The Need for Switches
Managing network traffic involves knowing what hardware to apply, such as a switch versus a router. It
also requires logical segmentation of the network. Using Virtual LANs (VLANs), for instance, can be
compared to assigning a lane on a highway for trucks only. Finally, just as a freeway system gives
priority to emergency vehicles, network traffic must be prioritized. The objective is to use various
mechanisms to assure that critical messaging traversing the network will always have enough resources to
guarantee it will arrive—and arrive on time.
4.6.1 Performance of Switches
In the past, nodes were simply connected together using hubs wherever possible to keep costs low. Their
limitations have already been covered. While hubs provide an easy way to add additional nodes and
extend the length of the network, they do not break up the actual network into discrete segments. That is a
job for switches.
Switches are a fundamental part of most networks. They make it possible for several users to send
information over a network at the same time without slowing each other down.
In a
fully switched network, switches replace all the hubs of an Ethernet network with a dedicated
segment for every node. Since the only devices on each segment are the switch and the node, the switch
picks up every transmission before it reaches another node. The switch then forwards the frame over the