User's Manual
V34bis Fax-modem - AJ 2885 P
AJ 2885 P - Page 33
After this leased line configuration is saved by the AT&W command, the modem will start
training on leased line if :
•
it is reset by ATZ or by a power restart,
•
the front panel button is pressed.
For V34 mode of connection, better disable the V8 preamble by the command : @OM1
Automatic Dial Backup
: the master or Originate modem is in charge of initiating the dialup
connection if case of leased line failure. Modems issue alarm beeps, set the backup 117 signal
and flash the DSR front panel led once the dialup connection is on. AJ2885P modems has an
embedded real time clock and calendar to disable dial backup connection outside working
week-day and week-end periods as to optimise the cost if the dialup connections.
Leased line look back
: modems check for leased line recovery when in dial backup from the
S56 timer (in minutes). Look back is continuous and safe through a specific handshake as to
avoid ineffective retrains on leased line.
Permanent link on dialup line
: a leased line like connection can be performed over dialup line
by setting S61 register to 1 (ATS61 = 1). This special mode does not comply with dialup
requirements : it is the user’s responsibility to use this mode on a private line only.
5.9.
V23 and Bell 202 T Modes on Leased Line
AJ2885P modem provides several V23 – BELL202 modes on leased line as summarized by the
following picture :
Type of connection
AT Command
Model
Classical 1200 / 75 V23 mode : on a 2 or 4 wire line,
full duplex link at 1200 BPS one way (@M11 modem
to @M10 modem) and 75 BPS the other way.
1200 BPS sender modem:
@A2@M11&R1
1200 BPS receiver
modem: @A2@M10&R1
All
Reversing 1200/75 V23 mode : the same mode can
be reversed through RTS signal control.
@M10 or @M11 command may be used since the
transmission mode depends on the RTS signal.
@A2 @M10 (or @M11)
&R2
All
1200 / 1200 half duplex : this mode does not provide
the 75 BPS return channel, and applies on 2 or 4 wire
lines. Reversal is under RTS signal control.
@A2 @M10 &R3 S26=10
All
1200 / 1200 full duplex : a full duplex FSK link on a 4
wire line only.
@A2 @M10 &R1 @OT1
BP ant BD
1200 / 1200 half duplex or carrier controlled mode or
Master – Slave mode : the same mode may be used
for multi-point or master- slave link. Master modem is
set for permanent transmission while slave modem
transmission is under RTS control.
The reversal delay is as fast as 30 ms which is
adjusted by the S26 register (in ms)
Maître : @A2 @M10 &R1
@OT1
Esclave : @A2 @M10 &R3
@OT1 S26=30
BP and
BD
DTE interface signal in half duplex configuration :
