CANOGA PERKINS 2240 Fiber Optic Modem - Manual (Page 96)

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Canoga Perkins
NOTE: Interface control of the loopback tests is only supported on the
following modular interfaces: RS-423 / RS-232C, RS-449, RS-530 and
V.35.
When activated, the Local Loopback test will cause all data transmission from the near
end (local) user device to be looped back toward the receive of that same device. The
data from the remote user device will not loop back (it will continue receiving data
from the local device), but the Loop On indicator at the far end turns on.
The loopback point is set at the electrical interface of the local modem (see Figure 5-1).
NOTE: If the local loopback modem is operating in Mode 5 (slave clock
mode), the remote device will receive garbled data because of the overall
timing configuration. The local loopback will function correctly.
5.2.2 Remote Loopback Test
When activated, the Remote Loopback test will cause all data transmission from the
near end (local) user device to be looped back after the optical sections of the remote
device.
The data from the remote user device also loops back locally at the electrical interface.
See Figure 5-2.
HOST
TERMINAL
HOST
TERMINAL
USER
TERMINAL
TX
RX
RX
TX
LOOP
ON
LOOP
REMOTE
SYNC
SYNC
LOOP
OFF
LOOP
ON
FIBER OPTIC LINK
REMOTE
LOOP
Figure 5-2.
Remote Loopback
from User-End
of Fiber Link