MultiModemDSVD User Guide 4 AT Commands, S-Registers, and Result Codes
31
Command: &M
n
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: &P
n
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: &Q
n
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: &S
n
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: &T
n
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.