User's Guide Modem 56

AT Commands

Page 111

AT&D Controlling Data Terminal Ready

The DTR signal is used to indicate to the modem whether your computer is ready to

communicate.

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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 ■ 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.

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S Register 25 determines how long DTR must be low before the modem recognises

it as such.

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S Register 57 determines how long DTR must be high before the modem

recognises it as such.

Range

0-4