MultiModemDSVD User Guide

4 AT Commands, S-Registers, and Result Codes

Command:

&Cn

Data Carrier Detect (DCD) Control

Values:

 

n = 0 or 1

Default:

 

1

Description:

&C0

Forces the DCD circuit to always be high.

 

&C1

DCD goes high when the remote modem’s carrier signal is de-

 

 

tected, and goes low when the carrier signal is not detected.

Command:

&Dn

Data Terminal Ready (DTR) Control

Values:

 

n = 0, 1, 2, or 3

Default:

 

2

Description:

 

This command interprets the high to low transition of the DTR

 

 

signal from the computer according to the supplied parameter.

 

 

The action taken depends on the current &Q setting.

 

&D0

&Q0, &Q5, &Q6: DTR is ignored (assumed high). Allows op-

 

 

eration with computers that do not provide DTR.

 

&D1

&Q0, &Q5, &Q6: DTR drop is interpreted by the modem as if

 

 

the asynchronous escape sequence had been entered. The mo-

 

 

dem returns to asynchronous command state without discon-

 

 

necting.

 

&D2

&Q0–&Q6: DTR drop causes the modem to hang up. Autoan-

 

 

swer is inhibited.

 

&D3

&Q0, &Q5, &Q6: DTR drop causes the modem to perform a

 

 

soft reset as if the Z command were received. The &Y setting de-

 

 

termines which profile is loaded.

 

 

&Q5 or &Q6 and +FCLASS=1 or +FCLASS=2: Same as for &Q0.

 

 

 

 

 

Note: If &D1, &D2, or &D3 is set, the modem will not dial

 

 

without a DTR drop.

 

 

 

Command:

&En

V.42 Error Correction Modes

Values:

 

n = 0, 1, or 2

Default:

 

1

Description:

&E0

V.42 non-error correction mode (V.42 disabled).

 

&E1

V.42 auto-reliable mode.

 

&E2

V.42 reliable mode (V.42 enabled).

Command:

&En

Modem-Initiated Flow Control

Values:

 

n = 3, 4, or 5

Default:

 

4

Description:

&E3

Flow control disabled.

 

&E4

CTS/RTS hardware flow control.

 

&E5

XON/XOFF software flow control.

Note: See also the L5 and &K commands.

Multi-Tech Systems, Inc.

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