Installation guide

Network Infrastructure for EtherNet/IP™
7-86
Selecting Components
7.2.6 Terminating Fiber-Optic Cable
Proper termination of fiber-optic cable can be a difficult process. If not performed properly, poor
connections can reduce the distance capability of the system. Tools are available to help judge the quality
of the termination and the fiber-optic cables.
Fiber connectors should only be installed by trained personnel. The channel performance can be
severely degraded by improper connector installation.
In some cases, field splices may be required. Fusion splices should always be considered over a
mechanical type of splice.
Fusion splices should be performed by trained installers.
7.3 Key Switch Selection Issues
The additional functions offered by managed switches can facilitate faster start-ups, allow more devices
to be connected without overloading the network, and add other capabilities often attributed to routers.
Managed infrastructure devices, such as switches and routers, are “intelligent” plant-floor devices. Users
of managed infrastructure devices can enable or disable different functions—just like PLCs. Downloading
the configuration parameters of a managed device, such as for a replacement switch, is no different from
reloading a replacement PLC with the correct program. Also like PLCs, if multiple switches have
different configurations, the engineer must maintain a library of configurations for specific switches.
Table 7-2 summarizes the types of functions that may be found in a managed versus an unmanaged
switch.
Table 7-2 Managed Switch versus Unmanaged Switch Functions
Switch Function Managed Switch Unmanaged Switch
Switched Ethernet: Eliminate collisions Yes Yes
10 Mbps to 100 Mbps data rates: Auto negotiation Yes Yes
10 Mbps to 100 Mbps data rates: Manual setting Optional Not available
Multicast message handling Optional Not available
Quality Of Service options Optional Optional
Security options Optional Not available
Virtual LAN: Forward messages Yes Yes
Virtual LAN: Configure/assign devices to a VLAN Optional Not available
Diagnostics: LED-based Yes Yes
Diagnostics: Software accessed (remote monitoring, web-
based, set trap addresses)
Optional Not available