MultiModemDSVD User Guide

4 AT Commands, S-Registers, and Result Codes

Command:

&Mn

Communications Mode

Values:

 

n = 0

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.

Command:

&Pn

Pulse Dial Make/Break Ratio

Values:

 

n = 0

Default:

 

0

Description:

&P0

Selects a make/break dial ratio of 39:61 at 10 pulses per sec-

 

 

ond.

Command:

&Qn

Asynchronous Communications Mode

Values:

 

n = 0, 5, 6

Default:

 

5

Description:

 

This command is an extension of the &M command, and is used

 

 

to control which connection modes are permitted. It is used in

 

 

conjunction with S36 and S48. (See also the \N command.)

 

&Q0

Selects direct asynchronous operation. See &M0.

 

&Q5

The modem will try to negotiate an error-corrected link. The

 

 

modem can be configured using S36 to determine whether a

 

 

failure will result in the modem disconnecting or falling back

 

 

to a non-error-correction connection. See also \N3.

 

&Q6

Selects asynchronous operation with speed buffering and no

 

 

error correction. Same as \N0.

Command:

&Sn

Data Set Ready (DSR) Control

Values:

 

n = 0 or 1

Default:

 

0

Description:

&S0

Force DSR high (on) at all times.

 

&S1

Let DSR go high only during a connection.

Command:

&Tn

V.54 Test Commands

Values:

 

n = 0, 1, 3, 4, 5, 6, 7, or 8

Default:

 

None

Description:

 

The modem can perform selected test and diagnostic functions.

 

 

A test can be run only when the modem is in asynchronous

 

 

operation in non-error-correction mode (normal or direct mode).

 

 

For tests 3, 6, and 7, a connection between the two modems

 

 

must first be established. To terminate a test in progress, the

 

 

escape sequence (+++) must be entered first, except for param-

 

 

eters 7 and 8. If S18 is non-zero, a test terminates automatically

 

 

after the time specified by S18 and displays the OK message.

 

&T0

Abort. Stop any test in progress.

 

&T1

Start local analog loopback, V.54 Loop 3. If a connection exists

 

 

when this command is issued, the modem hangs up. The CON-

 

 

NECT XXXX message is displayed upon the start of the test.

Multi-Tech Systems, Inc.

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