Chapter 3 - Troubleshooting; General; All Leds Are Off; Alarm Led - TC Communications TC2200R User Manual

Multi-drop (bus) fiber optic modem

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Table of Contents

General

Alarm conditions occur whenever an optical problem or "fault" condition is detected by the TC2200/2201.

Under normal operation, all LEDs should be lit, with the exception of either the "DTE" or "DCE" and

"ALARM" LEDs. The "BRD" and "RSP" LEDs will only light when there is activity on the bus.

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 rapidly and one or more additional LED will

flash. The following fault conditions will cause the alarm to be triggered:

1. Optic signal lost from "RxA" or "RxB."

2. Optic signal is marginal, which causes invalid data packets to be received; either the "SynA" or "SynB"

LED will be flashing.

3. Optic overdrive can cause the "SynA" or "SynB" LED to flash while optic "A" and/or "B" still receives

a valid signal.

4. One or more of the front panel's DIP switches is in the Down position.

5. The Anti-Streaming function has been activated.

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 Loss on the Fiber

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.

These are the reference values we use to calculate the loss on the fiber:

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.