D/I Mux III User’s Manual Appendix G. Modem Interfaces
252
Table H-4. Smartmodem 2400/2400B Command Set (Continued)
The following commands are used with newer model 2400 bps modems.
Command Description
&C0
&C1
Assume data carrier always present (DCD signal).
Track presence of data carrier.
This command (found on a large number of clones) causes the most problems when
moving to a 2400 bps modem from a slower speed. The default state is &C0, which
causes the software to react as though a lost carrier is present. When initializing a 2400
bps modem, always use &C1 as part of the initialization.
&D0
&D1
&D2
&D3
Ignore DTR signal.
Assume command state when an on-to-off transition of DTR occurs.
Hang up and assume command state when an on-to-off transition of DTR occurs.
Reset when an on-to-off transition of DTR occurs.
As with the &C0 command, the factory default (&D0) is not the most logical choice, and
most software expects that lowering DTR hangs up the line. Be sure to use &D2 as part of
the modem initialization sequence to avoid problems.
&F
Recall factory settings as active configuration.
&G0
&G1
&G2
No guard tone.
550 Hz guard tone.
1800 Hz guard tone.
Some telephone systems require other than the default &G0 for guard tone.
&J0
&J1
RJ-11/RJ-41S/RJ-45S telephone company jack (intended for single-line phone systems).
RJ-12/RJ-13 telephone company jack (intended for multi-line systems).
&M0
&M1
&M2
&M3
Asynchronous mode.
Synchronous mode 1.
Synchronous mode 2.
Synchronous mode 3.
&P0
&P1
Pulse dial make/break ratio = 39/61.
Pulse dial make/break ratio = 61/39.
These options are provided for different national phone systems.
&Q0
&Q1
&Q2
&Q3
&Q4
Asynchronous mode.
Synchronous mode 1.
Synchronous mode 2.
Synchronous mode 3.
Synchronous mode 4.
These commands are alternatives to the &Mx commands listed above.