Westermo GDW-11 - Manual (Page 4)

4 AT command syntax 6615-2220
AT command syntax
Command line
All commands always start with AT (ATtention) and are terminated with .
There are 3 exceptions to this rule:
… The A/ command is not terminated with .
… Some commands where input text is the final parameter to the command is
terminated with character (ASCII 26 or ). One example of such command
is AT+CMGS.
… The command to switch from “on-line mode” to “online command mode”
is +++ and this command is not terminated with
There are 3 different types of commands that differ slightly in command format and the
command response:
… Standardized basic commands
… Register commands.
… Extended commands.
The basic commands are commands not preceded by a ‘+’ character.
Most of the basic commands originate in the V.25ter [TBD] standard.
Action Command Example
Set/Execute CMD[x] AT&D2, AT&W, ATD
The register commands is a set of S-registers that contain parameter values needed by
the modem in different modes.
Syntax: ATSx=
Test command: ATSx?
Possible values: ATSx=?
The S-registers are saved by the AT&W command and Refer to section “S-registers”
for more information.
Every extended command has a test command (trailing =?) to test the existence of
the command and to give information about the type of its subparameters. Parameter
type commands also have a read command (trailing ?) to check the current values of
subparameters. Action type commands do not store the values of any of their possible
subparameters, and therefore do not have a read command.
Figure 1: Basic structure of
a command line
ATCMD1 CMD2=12; +CMD1; +CMD2=,,15; +CMD2?; +CMD2=?
command line prefix
basic command
(no + prefix)
subparameter
extended command
(prefixed with +)
extended commands are
delimited with semicolon
subparameters
may be omitted
command line
termination character
read command for checking
current subparameter values
test command for checking
possible subparameter values