Specifications

Chapter 6 Troubleshooting and Diagnostics Installation and Operation Manual
6-16 Testing the Unit FCD-E1LC Ver. 1.0
6.5 Testing the Unit
The diagnostic loopbacks and tests are used to identify rapidly and efficiently the
location of a problem that prevents normal service.
A diagnostic loopback is activated by entering the appropriate LOOP (or LP)
command, and is deactivated using the CLR LOOP (or CLR LP) command. This
section provides a general description of each loopback and test.
Before executing a test, pay attention to the following:
• If a loopback is already connected, the TST indicator lights.
• If you try to connect a loopback while another loopback of the same type is
already connected, FCD-E1LC displays an error message.
• Not all of the loopback combinations are allowed.
For the list of allowed loopback combinations, refer to
Allowed Loopback
Combinations
on page 6-24 .
• No loopbacks are available for the Ethernet interface. In addition, main link
loopbacks should not be activated on an FCD-E1LC with Ethernet interface
while the Ethernet interface is connected to the LAN. This would cause a
state of permanent collision on the LAN, which would prevent other users
from using the LAN as long as the loopback is connected.
Overview of Test and Loopbacks
The FCD-E1LC supports the following types of test and loopback functions:
• Main link:
 Main link local analog loopback (LP LOC ANA ML)
 Main link remote analog loopback (LP REM ANA ML)
 Main link local digital loopback (LP LOC DIG ML)
 Main link remote digital loopback (LP REM DIG ML)
 Inband-activated loopback (LP INBAND ML) on the main link
 BER testing (LP BERT ML)
• Sublink:
 Sublink local analog loopback (LP LOC ANA SL)
 Sublink remote analog loopback (LP REM ANA SL)
 Sublink local digital loopback (LP LOC DIG SL)
 Sublink remote digital loopback (LP REM DIG SL)
• Data channel:
 Data channel local loopback (LP LOC CH)
 Data channel remote loopback (LP REM CH).