4 AT Commands, S-Registers, and Result Codes

Command:

&Gn

 

V.22bis Guard Tone Control

Values:

 

 

n = 0, 1, or 2

Default:

 

 

0 (North America), 2 (elsewhere)

Description:

&G0

 

Disables guard tone.

 

&G1

 

Sets guard tone to 550 Hz.

 

&G2

 

Sets guard tone to 1800 Hz.

 

 

 

 

 

 

 

Note: The &G command is not used in North America, and

 

 

 

may not be permitted in some countries.

 

 

 

 

Command:

&Kn

 

Flow Control Selection

Values:

 

 

n = 0, 3, 4, 5, or 6

Defaults:

 

 

3 (data modem mode)

 

 

 

6 (fax modem and voice modes)

Description:

&K0

 

Disables flow control.

 

&K3

Enables CTS/RTS hardware flow control.

 

&K4

Enables XON/XOFF software flow control.

 

&K5

Enables transparent XON/XOFF flow control.

 

&K6

Enables both RTS/CTS and XON/XOFF flow control.

 

 

 

 

 

 

 

Note: See also the &E command

 

 

 

 

Command:

&Mn

 

Communications Mode

Values:

 

 

n = 0–3

Default:

 

0

Description:

 

 

This command determines the DTR operating mode. The mo-

 

 

 

dem treats the &M command as a subset of the &Q command.

 

&M0

 

Selects direct asynchronous operation. Note that the command

 

 

 

sequence &M0\N0 selects normal buffered mode, but the

 

 

 

command sequence \N0&M0 selects direct mode. This is be-

 

 

 

cause the \N0 command is analogous to the &Q6 command.

 

&M1

 

Selects synchronous connect mode with asynchronous offline

 

 

 

command mode.

 

&M2

 

Selects synchronous connect mode with asynchronous offline

 

 

 

command mode. Same as &M1 except that &M2 enables DTR

 

 

 

dialing of directory slot 3. The modem disconnects if DTR is

 

 

 

low for more than the period stored in S25.

 

&M3

 

Selects synchronous connect mode. This mode allows DTR to

 

 

 

act as a talk/data switch. The call is manually initiated while

 

 

 

DTR is inactive. When DTR becomes active, the handshake

 

 

 

proceeds in originate or answer mode according to S14 bit 7.

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Multi-Tech Systems MT5600BL, MT5600BA manual 22bis Guard Tone Control, Flow Control Selection, Communications Mode