User Manual

Table Of Contents
Appendix A
Modem AT Commands
19
Xircom Inc. Mini PCI User’s Guide
Appendix A
Modem AT Commands
This section provides the following information:
Introduction to Modem AT Commands
Special Commands
AT Command Reference
Introduction to Modem AT Commands
Modem AT Commands With the exception of the Special Commands, all commands must be preceded by
the
AT
attention code (or command prefix) and terminated by pressing the
Enter
key.
The modem responds with the result code
OK
, which means it understands and can execute the command,
or with
ERROR
, which means that the modem does not understand the command or that the command is
invalid.
The modem must be in command mode when any command other than the online escape sequence is
entered. Commands entered when the modem is in online mode are treated as data and transmitted as such
to the modem at the other end of the line.
Some commands are used in coordination with S-Registers.
Special Commands
+++ Online Escape Sequence
The escape sequence is used to switch to command mode from online mode during a session with a
remote modem. Type three "plus signs." The escape sequence is not preceded by the AT command prefix,
nor does it require the Enter key. The setting of S-Register S2 determines the ASCII character used.
S2=43 is the default (the "+" sign). 0-127 are valid. To disable the command, set S2 to a value greater
than 127. Use the
ATO
("AT" and letter "O") command to return to online mode.
Insert a pause before and after the escape sequence to prevent misinterpretation of the escape sequence as
data. Use S-Register S12 to set the length of the pause.
A/ Repeat Last Command
The
A/
command causes the modem to repeat the last command string. The command executes as soon as
/
is typed. It does not require the AT command line prefix, nor does it need to be followed by Enter.