KE LOGEM LGH 28.8D1, Operation Manual, Page: 157 / 200

157 Operation Manual V.34 - Modems, Version 07/97
Chapter 7
7.2.4 Leased Line Operation with Dial Backup
Leased lines are implemented with applications that need permanent
access to data from a host system. At line failures access to current data
might not be possible for a longer period. This is no problem if the modems
are equipped with the optional dial backup board as they can backup the
operation during failures or breakages on the route. Using a second
modem chip the leased line is monitored permanently in parallel to the
switched line. The switched connection is terminated if the leased line is
oparational again after failures. The modems switch back automatically
to leased line operation.
öffentliches
Fernsprechnetz
HOST
REMOTE
4-Draht-
Standleitung
S1 M2 D1 M5 D2 A/O Da/Te
LOGEM ®
928
S1 M2 D1 M5 D2 A/O Da/Te
LOGEM ®
928
During normal operation the modems operate on a leased line (2 or 4
wire). The LED indicators A/O or ANS (rackmounted version) are not active
for this operation mode.
The modems change automatically to switched line operation if the leased
line is interrupted. The modem that has a phone number in his phone
number storage Z0 initiates the establishment of a connection. To avoid
any calling conflicts only one of the communicating modems may have
an allocated number storage Z0. Otherwise the modem issues a BUSY
report as the desired subscriber seems to be occupied. You may allocate
further number storages as the modem would try to connect to other
subscribers after an unsuccessful attempt to establish a connection. If a
number storage is not allocated the modem starts again with the number
from Z0 at the next establishment of a connection. The modem with a
not allocated Z0 number storage waits generally as a slave for the next
call to come. The LED A/O or ANS at the front side of the modem blinks
at an established switched connection.
Attention! The utilization of the switched line is subject to special
charges! This operation mode causes additional line
costs!
Applications