User manual
DEFINITY ECS Release 8.2 Maintenance for R8.2csi 
555-233-119  Issue 1
April 2000
Maintenance Objects 
3-600DS1-BD (DS1 Interface Circuit Pack) 
3
CSU Repeater Loopback Test (#1211)
This test is destructive.
The CSU Repeater Loopback (RLB) Test causes a loopback at the far-edge of 
the local 120A CSU Module or T1 Sync Splitter, and tests the connection from the 
TN767E DS1 board to and including the CSU Module/T1 Sync Splitter circuitry. 
This test will only be performed if the 120A CSU Module/T1 Sync Splitter is 
present, administered, and connected to a 1.544 Mbps TN767E DS1 circuit pack 
on the back of the port carrier.
The test is destructive and can only be initiated by a system technician 
demanded 
test ds1-loop UUCSS ds1/csu-loopback-tests
 command.
All trunks or ports on the DS1 Interface circuit pack must be busied out via the 
system technician 
busyout board
 command before running the RLB Test.
When the RLB Test is initiated, maintenance software sends an appropriate 
message to the TN767E DS1 Interface circuit pack to start the test. The board will 
set up the RLB loopback, transmit a test pattern, and verify that the pattern is 
received unaltered through the loopback. If the transmitted and received pattern 
is different, the test fails.
In addition, the DS1 circuit pack hardware applies a DC current while the test is 
running in order to detect any broken wires which may not be detected by the 
loopback pattern.
When the test is complete, all trunks or ports on the TN767E DS1 Interface circuit 
pack are restored to the in-service state after the 
release board
 command is 
entered.










