Case Communications syncro 1496, Справочное руководство

Страница: 86 / 192

6.5 Rate Adaption (Fallback/Fallforward)
Rate adaption is the facility which allows your modem to change its
connection speed to the remote modem. This may be achieved either
manually or automatically.
6.5.1 Manual Fallback
Fallback operation may be selected by the following methods:
– Pressing the
FB
button on the front panel
– Using the
%F
command
– Using the %B command to determine the way the modem will react to
pin 23 on the V.24 interface.
You can see whether the modem is in primary or fallback mode by using
the
*C
command and checking the display (
%F0
= primary rate,
%F1
=
fallback rate).
6.5.2 Auto Fallback
Auto fallback is the facility which allows your modem to change its
connection speed in response to the prevailing line conditions.
The relevant commands are:
''Q Leased line quality monitor
/Q PSTN quality monitor
''G
Good signal quality threshold
''P Poor signal quality threshold
''M Signal quality summary
When enabled, the signal quality monitor facility monitors the quality of
the signal received from the line. If the quality falls below that set by the
''P command, the modem will request a fallback to a slower connection
speed.
Once the signal quality increases beyond that set by the ''G command, the
modem falls forward to a faster connection speed, up to the maximum
defined by the primary modulation format (set by the
F command).
The PSTN quality monitor may also initiate a re-dial, if the line quality
does not improve.
X450-310851 Issue 2 6-10 Rev.0