Black Box MD885A-R3 Modem User Manual


 
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4.0 General Operation and Special Features
4.3.1 A
UTODIAL
B
ACKUP
The Modem automatically dials the stored number to connect over the backup
line if it detects poor signal quality (ER) or a loss of carrier detect (CD) on the
leased line. The criteria used by the Modem in assessing the condition of the
leased line depend upon the settings of the Signal Quality option (one error
in 10
3
or 10
5
bits) and the Carrier Detect Level option (-43,
-33 or -26 dBm).
When Dial Backup occurs (either automatically or by operator intervention),
the following message flashes on the front-panel LCD of both modems:
The message clears when the modem returns to the leased line. If you want
to clear the message while the Modem is still in dial-backup mode, press
the ENT pushbutton.
4.3.2 E
XIT
F
ROM
L
EASED
L
INE
A
UTO
-R
ECOVERY
If the Leased Line Auto-Recovery Return option is enabled (see below),
the Modem automatically exits the Auto-Recovery mode when leased-line
conditions are satisfactory. Any normal disconnects (such as loss of carrier
or line current) may also disconnect the dial connections and return
communication to the leased line. To ensure the proper disconnect
capabilities for Leased Line Auto-Recovery mode, both the line current
disconnect (CURRENT DISC’T screen) and carrier disconnect (CARRIER
DISC’T) options must be enabled on both modems. To manually exit the
Leased Line Auto-Recovery mode and return to leased line operation, select
DIAL from MAIN MENU screen 1, and then select HANGUP from the
AUTO-DIAL screen.
4.3.3 L
EASED
L
INE
A
UTO
-R
ECOVERY
O
PTIONS
Three options allow you to specify the criteria the Modem uses in
determining when to enter and exit the Leased Line Auto-Recovery mode:
• Leased Line Auto-Recovery Select (Select)
• Return From Leased Line Auto-Recovery (retn)
• Test Interval (Test)
The Leased Line Auto-Recovery Select option determines the type of Leased
Line Auto-Recovery desired. “DIAL IF BAD >> (1, 2, 3 or 4) min” means dial
backup occurs if bad line conditions are present for the number of minutes
selected. To disable Leased Line Auto Recovery, select NO AUTO
RECOVERY. A sixth option, Manual Recovery, is discussed below.
ATTENTION:
DIAL BACKUP
12
3