Black Box 32144, Руководство пользователя

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33
CHAPTER 2: Quick Start
2.9.1 V.32 D
IAL
B
ACKUP
NOTE
Dial backup can only be used
in point-to-point applications.
To prevent service interruption
in case of poor leased line
conditions, the modem can be
configured for V.29 leased line
operation with V.32 dial backup.
This means that the modem will
use dial lines to automatically
restore operation when conditions
on the leased lines deteriorate.
(The modem will use V.32
modulation for dial backup.) To
set up the modem for V.29 leased
line operation with dial backup,
follow these steps:
1. Select the 4-wire leased line
V.29 (4-WLL V.29) Quick Setup
on both the local and remote
modem.
2. One modem must be set to
originate mode and the other
to answer mode. To make this
selection, use the ANS/ORG
DEFAULT screen on the front
panel LCD.
3. Configure the modems for
leased line auto-recovery, as
explained in
Chapter 4 .
2.10 V.29 Fast Master and Slave
Modes (Quick Setups 14–15)
NOTE
Modems used in a V.29 Fast
Master and Slave (multidrop)
configuration must be modems
that support V.29 operation.
In multidrop operation ( Figure
2-4 ), the master modem transmits
to all of the slave (remote) modems.
When the DTE at a slave site
recognizes its own address in the
polling protocol, it raises RTS to
the slave transmitter. The slave
responds by transmitting a special
training sequence, then raising
CTS and transmitting the data
from the DTE. When the DTE has
completed transmission, it lowers
RTS and the modem will drop
carrier to let the next modem on
the poll list use the channel.