Remote Digital
The Remote Digital Loop with 511/511E is
Loop with
shown above. After RDL is established the
511/511E
Remote units' Restart Timer is set to one
minute. This has been done because when the
511/511E generator is started on the local unit,
the Remote framer begins seeing unframed
packets. The Remote unit can not distinguish
the 511/511E pattern from the line being discon-
nected so the Restart Timer has been length-
ened to allow the pattern generator to function.
Once the 511/511E test is started, the Local unit
changes its' Restart Timer to one minute. The
pattern originates within the Processor and is
sent to the Remote unit. It is then looped back
to the Local unit where it is evaluated for errors.
After 45 seconds, the Pattern Generator will
timeout and stops sending the pattern. The ER
led will begin blinking until the user turns off the
511/511E switch.
Figure 12. Block Remote Loop with 511/511E
23
Data Mode with
When the units enter DataMode it is possible to
511/511E Pattern
turn on the 511/511E pattern generators on
Generators
both ends of the link. Once a 511/511E pattern
is selected on one end of the link, the pattern
generator will begin transmitting unframed
511/511E through the line to the Remote end. A
possible problem with this test can occur due to
the Restart procedure. Once the Local 511/511E
is turned on, the Remote unit begins receiving
an unframed 511 pattern. If the Remote unit
does not turn on the 511/511E-pattern generator
within 4 seconds, the Remote unit will Restart
and enter the StartUp mode. Note that once the
511/511E-pattern generator is started the
Restart timer is changed to one minute (only on
the unit which has the pattern enabled). If both
units enable the 511/511E pattern within 4 sec-
onds of each other, both units will be transmit-
ting and receiving the 511/511E pattern. Both
framers are now receiving unframed data and
will restart after one minute. The 511/511E pat-
tern generators will TimeOut after 45 seconds
re-enabling the normal data path. The ER led
will begin flashing until the user terminates the
test.
Figure 13. Block Diagram DataMode with 511/511E
24
Pattern
Gen/Det
Loop
Contr
ol
Loop
Contro
l
Pattern
Gen/Det
Processor
Processor
Framer
Framer
Line
Pattern
Gen/Det
Loop
Contr
ol
Loop
Contro
l
Pattern
Gen/Det
Processor
Processor
Framer
Framer
Line
