Black Box MD1276A, User Manual

Page: 109 / 289

AT Commands
Page 109
AT&D Controlling Data Terminal Ready
The DTR signal is used to indicate to the modem whether your computer is ready to
communicate.
+ The &D command will only take effect when the DTR option switch is in the UP
position and %S0 is selected. (See the Dumb Mode Section for details.)
Options
AT&D0 The modem ignores the DTR signal and acts as if it is asserted (the modem
assumes the computer is ready to communicate).
AT&D1 The modem will return to on line command state if DTR is lowered during a
connection.
AT&D2
n
The modem will hang up, return to local command state and disable auto-
answer whilst DTR is low (is not asserted).
To enable auto-answer, the DTR signal must be asserted.
The computer must assert DTR before dialling or answering may commence.
AT&D3 If DTR is lowered, the modem will hang up, return to local command state
and initialise itself with the values stored in the &Y profile.
AT&D4 The modem will hang up, return to local command state and go off-hook. It
will remain off-hook whilst DTR is low.
+ S Register 25 determines how long DTR must be low before the modem recognises
it as such.
+ S Register 57 determines how long DTR must be high before the modem
recognises it as such.
Range
0-4
See Also
S 25, S 57 DTR Detection Times