Technical data

78 Theoretical and general applications www.westermo.com
AT-commands
A telecom modem works in two modes:
… Command mode.
… Communication mode.
In command mode you can configure your modem so that it works with your applica-
tion. Communication mode is the mode when the modem is connected to another
modem and is exchanging data.
As previously mentioned, Hayes Microcomputer Products developed a command
set that has become the de-facto standard, a.k.a. the Hayes
®
-commands. These com-
mands are used partly to configure the modem and partly to initiate a connection.
As the AT-commands have become a standard for telecom modems, there are
great similarities in how these are used. Nevertheless, you should be aware that there
are differences depending on how advanced a modem is in relation to another
modem. Some of the most important commands for our modems are presented
below, for detailed description of these please refer to respective installation manuals.
ATA – Answer
Forces a modem in command mode to answer a current incoming call.
The modems perform handshaking to establish a connection. Once the
connection is established the modems switch to communication mode.
ATDn – Dial
Makes a modem in command mode initiate a call. (n) is usually the telephone
number but there are various other codes for example, to generate a pause dur-
ing the dialling of the number if the modem needs to wait for a dial tone through
a switchboard. Once the connection is established the modems switch to com-
munication mode.
ATH – Hang-Up
The modem terminates the connection and hangs up. In order to use this com-
mand it is necessary for the modem to be switched from communication mode
to command mode normally using the code +++.
AT&Fn – Restore Factory Configuration
Resets the modem to the factory default settings, or configuration profile 0
or 1.
B A C K