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.
5.3.3 Using the V.52 (BER) Test Pattern Generator
To use the V.52 BER tests in conjunction with the Remote Digital
Loopback tests (or with Local Line Loopback tests), follow these
instructions:
1.
Locate the “511/511E” toggle switch on the front panel of the
1088 and move it UP. This activates the V.52 BER test mode
and transmits a “511” test pattern into the loop. If any errors
are present, the local modem’s red “ER” LED will blink
sporadically.
2. If the above test indicates no errors are present, move the
V.52 toggle switch DOWN, activating the “511/E” test with
errors present. If the test is working properly, the local
modem's red “ER” LED will glow. A successful “511/E” test
will confirm that the link is in place, and that the Model
1088’s built-in “511” generator and detector are working
properly.
27
28
NOTE:
The above V.52 BER tests can be used independently
of the Remote Digital Loopback tests. This requires two opera-
tors: (1) to initiate and monitor the tests at the local Model 1088,
and (2) to do the same at the remote Model 1088. In this case,
the test pattern sent by each Model 1088 will not be looped back,
but will be transmitted down the line to the other Model 1088.
While one operator initiates test, the other monitors for errors.
Pattern
Gen/Det
Loop
Contr
ol
Loop
Contro
l
Pattern
Gen/Det
Processor
Processor
Framer
Framer
Line
Figure 18. Block Diagram DataMode with 511/511E
