Operation
Command Mode Overview
3-22
SpectraComm Dual V.34 Modem
060R122-000
Installation and Operation
Issue 15
AT Commands
In command mode the modem looks at everything you type on the DTE keyboard. When the
modem detects a valid command, it will be executed. AT commands can cause the modem to
answer a call, hang up or dial, change an S-Register value, or perform other command functions, as
described later in this manual.
Command Syntax
An AT command takes the form of a single letter or a combination of a letter and a modifier
character, often followed by one or more numeric characters. The modem interprets the AT
command as a direction to set a configuration parameter or perform an action. The command (letter
or letter and modifier) identifies the parameter or action, and the numeric value specifies (from a
pre-established range of choices) how the parameter is to be set or how the action is to be performed.
Some AT commands, such as those used to program telephone numbers, involve further
modification through the use of an equal sign (
=
) followed by additional numeric characters.
You send AT commands to the modem individually or in a command string of up to 40 characters,
not including spaces and line feed characters. Each command or command string begins with
AT
and ends with a carriage return. The letters
AT
stand for
AT
tention and signal the modem that a
command(s) will follow. The AT prefix also permits the modem to determine the asynchronous data
rate and parity settings of the local DTE. You can type either
AT
or
at
, but mixed-cases (such
as
At
or
aT
) will not give predictable results.
Multiple commands in a string may be separated by space or line feed characters to improve
readability, although they will be ignored by the modem. A carriage return character must be
entered at the end of a command line to signal the modem to process the command string. Correct
mistakes by using the
backspace
, or
CTRL-H
to delete characters to the left. The AT prefix
cannot be deleted.
Command Buffer
When the command line is sent to the modem, it is loaded into a command buffer with a capacity
of 40 characters. The AT prefix, spaces, line feed characters, and carriage return are not loaded into
the buffer, and so do not count as part of the 40-character limit. If a command line is more than 40
characters long, the modem will only act on commands that are contained in the first 40 characters.
The
A/
command instructs the modem to re-execute the command line currently in the buffer. It
is to be sent to the modem as a command line that consists of only the
A/
command and a carriage
return - no AT prefix. This is the only command line that does not begin with the AT prefix.
Note
Some AT commands can be issued from the modem's front panel. Refer to Table 3-1:
in this Chapter.
Note
The command for displaying basic AT command set help is simply
$
.
This command can be combined
with any of the valid modifiers to display help for the extended AT command sets.
Note
AT Command Syntax Exceptions: The
A/
command does not require the AT command line prefix.
Summary of Contents for 060A027-001
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