Synchronous Mode 2: Stored Number Dial &Q2
In this mode, the modem supports a synchronous-only DTE or a PC with a synchronous
adapter card. In synchronous mode 2, the modem automatically dials a number
stored in location 0 (see the &Zn=x command) when the modem detects
an off-to-on transition on DTR (when it is turned on). When configuring
the modem for this mode, result codes should usually be turned off (the
Q1 command option) as some computers do not interpret responses from the
modem correctly. The modem can be placed in the asynchronous command state
while &Q2 is in effect, but the D and A (Dial and Answer) commands are disabled.
The modem exits the synchronous online state and returns to the asynchronous
command state after detecting a loss-of-carrier exceeding the time interval
stored in S10.
An on-to-off-transition of DTR causes the modem to hang up and return to
the asynchronous command state. For the responses associated with transitions
of the DTR signal for this mode, See the &D command.
Synchronous mode 2 is similar to the ITU-T Recommendation V.25bis (Direct
call and/or answer controlled by the DTE).
The following diagram depicts modem operation in synchronous mode 2:
Once this mode is selected, the modem may go off-hook and begin dialing
the stored number when the modem is connected to the terminal. To delay
this transition, turn the modem off (place the power switch in the down
position) before connecting the devices. When the connection is completed,
turn the modem back on. When DTR is off, auto-answer is disabled p;
regardless of the &D option selected.