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CHAPTER 5: Operation
Figure 5-6. Local loop mode 2 with 511/511E.
Remote Digital Loop
The Remote Loop uses the EOC channel (an 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 processor 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 5-7. Remote loop.
Framer
Processor
Processor
Framer
Pattern
Gen./Det.
Pattern
Gen./Det.
Loop
Control
Loop
Control
Line
X
X
Framer
Processor
Processor
Framer
Pattern
Gen./Det.
Pattern
Gen./Det.
Loop
Control
Loop
Control
Line
X
X
