Chapter 6 - Troubleshooting; General; All Leds Are Off; Alarm Led - TC Communications TC3720 User Manual

Self-healing industrial ethernet fiber optic switch

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Table Of Contents

Table of Contents

General

Alarm conditions occur whenever an optical problem or "fault" condition is detected by the TC3720's.

All LEDs are Off

If no LEDs are lit on the unit, check the DC power supply, terminal block connector plug, and/or the power

source. If the problem persists, contact the Technical Support Department at TC Communications, Inc.

Alarm LED

When an alarm condition is detected, the ALARM LED will flash. The following fault conditions will cause

the alarm to be triggered:

1. Power is lost to any unit in the SHR. This will cause adjacent units to go into alarm, indicating a fault in

the SHR.

2. Fiber optic cable breakage in the SHR will also trigger an alarm condition.

Other LEDs

1. Any fiber optic cable breakage in the SHR will trigger an alarm condition between any two adjacent

units as well as on the Master. Depending on which fiber port F1 or F2 the breakage occurs, the

corresponding F1/1X or F2/X2 LEDs will also flash.

Optic Cable Types

Conventionally, fiber optic cable with yellow-colored insulation is used for Single Mode applications; gray or

orange-colored insulated cable is for Multimode use. If Multimode cable is used in a Single Mode application,

the test results could be erroneous and confusing.

Calculating the Fiber Optic Loss Budget

The fiber optic link and/or connectors are frequently the source of various problems. Check out the

connectors and the integrity of the link first. Ideally, the link should be calibrated for total loss after the

installation has been completed. This will accomplish two things: (1) it will verify that the total loss of the

link is within the loss budget of the device and (2) it will provide a benchmark for future testing. For example,

a system that has been tested as having 6dB total loss when installed and suddenly tests out as having a loss

of 10dB probably has a connector or link problem.

To calculate the loss budget:

Multimode 850nm

Multimode 1310nm

Single Mode 1310nm

Single Mode 1550nm

*These numbers are listed for reference only. We recommend an OTDR reading be used to determine actual link loss.