Rockwell Automation 1786-series ControlNet Fiber Media Planning and Installation Guide - Manual (Page 57)

Rockwell Automation Publication CNET-IN001C-EN-P - October 2011 57
Verify Your Network Chapter 5
Considerable power loss in your cable could be a result of the
following conditions:
• Poor splices
• Improper bend radius
• Bending losses
• Broken fibers
• Poor connections
• Contaminated or damaged connectors
• High fiber bend radius
• Poorly polished connector
OTDR Measurement In addition to power loss measurement, you should examine your total fiber
network by using an optical time domain reflectometer (OTDR). The OTDR
emits light into a strand of fiber optic cable and displays the reflected light.
OTDR tests provide the following measurements that will help you troubleshoot
and maintain your network.
• Total distance along the cable to a fiber break
• Distance to an event (splice, bend, connector) that attenuates the light
• Distance between two attenuating events
• Light attenuation between two points of the cable
• Total reflected light or light reflected from a single event
Keep records of the traces for each cable strand on either hard copy or
computer backup.
IMPORTANT Disconnect the fiber modules from the fiber cables before performing
an OTDR test.