29
30
Remote Digital
The Remote Loop uses the EOC channel (an
Loop
out-of-band signaling channel) to establish the
remote link. Upon the RDL switch being thrown
or DTE initiation, a RDL_ON Request signal is
sent to the remote unit. The Remote unit then
responds with an RDL Acknowledge command
and the link is established. Data originates at the
local DTE and is looped at the Remote DSP
back to the Local DTE. Note that the data is also
passed through to the Remote DTE and is not
squelched. When a Remote unit enters RDL, it
changes its' Restart timeout to one minute (the
reason will be explained in the RDL with
511/511E section). If the line is disconnected,
the local unit will Restart (NS led activated) after
4 - 6 seconds, but the Remote unit will wait for
one minute before it Restarts. Note that the
transmit data at the Remote DTE is ignored.
When the switch is thrown or the DTE removes
the RDL request, the local unit will transmit an
RDL_OFF Request to the Remote unit. The
local unit will keep its' TM led active until this
request has been completely sent out. If the
switch is thrown again before the completion of
the termination phase the switch will be ignored
until it is placed back into the normal position.
Figure 17. Block Diagram Remote Loop
Remote Digital
The Remote Digital Loop with 511/511E is
Loop with
shown below. 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 DSP 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 18. Block Remote Loop with 511/511E
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
