CANOGA PERKINS 2240 Fiber Optic Modem - Manual (Page 24)

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Canoga Perkins
2.2.2.1 Carrier Detect (CD) Signal Options
There are two switches on the internal switch block which control the response of
the CD signal on the Standard Data Interfaces. These switches operate as a pair
and only one switch should be set to ON at any time.
Factory Setting = CD / DCD set to OFF
CD / SYNC set to ON
The CD signal may be used as an output for an end-to-end Control Channel by
setting the CD / DCD switch to ON and the CD / SYNC switch to OFF. This setting
is used only with Standard Data Interfaces that do not support the expanded
interface connector on MC1 and MC2.
The factory setting causes the standard data connector CD signal to track the state
of the modem’s optical receive synchronizer. CD will assert when the modem is
in local sync. This also means that CD will track the state of the front panel Local
Sync LED.
On expanded data interfaces, the standard data connector CD signal in the CD =
local sync mode (factory setting) can be used to gate CTS (or its equivalent signal)
OFF when the modem’s receiver is out of sync. See Figure 2-4 for an illustration
of this factory setting.
Refer to the sections on the RS-449, RS-530, V.35, MC1 and MC2 interfaces for
more information about the CD-CTS gating function.
CD/DCD
or CD/SYNC
selector switches
(DCD = RTS from
far end)
Optical
Receiver
Rx Fiber
Front Panel LED
To
Interfaces
J2 = Standard data
connector
J3 = Expanded data
connector
RTS from far end
Local Sync
CD Figure 2-4.
Factory Setting
for CD / DCD or
CD / SYNC
Switches