Verilink Access Manager 2000 (896-502037-001) Product Manual - Manual (Page 320)

Monitoring and Troubleshooting Access Manager
8-50 Access Manager 2000 User Manual
Figure 8-1 DIU 2140 loopbacks
The selected data equipment transmitter is connected to the data receiver
through the associated interface driver and receiver in the DIU. This
looping path allows you to check the operation of the data equipment and
associated cabling to the DIU. The data port of the DIU is also looped
back toward the far-end EQP. This path allows you to perform end-to-end
data port tests and check the EQPT circuit end-to-end.
Before starting this procedure, determine the appropriate CSU timing for
the DIU loopback. For example, avoid split timing: when a DIU loopback
is set,
THROUGH timing with non-synchronized timing sources for
receive data and transmit data is invalid and introduces errors.
In general, DIU loopbacks may introduce errors if the CSU is THROUGH
timed.
To activate or deactivate DIU loopbacks
1. When you get the On-line Access sub-menu, select the
Loopbacks option.
2. The Specify Circuit Element to Receive Loopback screen appears.
• The first field is DIU Shelf Numbe . Enter the shelf
number of the plug-in DIU circuit element which will receive
the loopback request.
• The second field is DIU Plug Numbe . Enter the slot of the
plug-in DIU circuit element which will receive the loopback
request.
DIU 2140
EQUIPMENT
Driver
Receiver
INTFC
and
Logi
Circuits
RS422
CPU
XMTR
CPU
RCVR
XMTR
and
RCVR
DUSARTs
BACKPLANE
DATA BUS
TO/FROM
NCC 2020
OR
TAC 2010
Procedure for
loopbacks