AT Commands - Attention (AT) commands are the means by which you control and monitor a

Basicsmodem. Typically, the communications application automatically issues them, and you need not know the commands and their options.

However, to custom-configure the modem for an application, or to optimize performance, you can issue commands through the communications application yourself. In most communications applications, there is a menu item, or option, for entering extended or custom AT commands. See your communications application documentation.

You can also configure the modem by issuing AT commands directly from a simple terminal-emulation application such as ZTERM and PowerTerm.

To issue an AT command from the terminal-emulation application, you must ensure that the modem is in command mode (in which it can detect and respond to commands), rather than data mode (in which it is transmitting and receiving data). To enter command mode from data mode, enter +++. You need not press the ENTER key.

When entering AT commands, the following basic rules apply:

AT commands can be entered in uppercase, lowercase, or mixed text

The characters AT begin all AT commands, except A/ and +++

The key used as the ENTER key is specified in S-Register S3

The maximum command length is 64 characters.

You can enter more than one AT command on a line, and you can chain commands using just one AT at the start. However, some commands must occur at the beginning or end of the command line.

Some of the AT commands and options are product specific and may not be applicable to the product you are using.

+++(Plus-Plus-This command, known as the escape sequence, causes the modem to stop Plus) Commands transmitting data (if it is doing so), and go into command mode.

Issue this command at the computer keyboard, in the communications application's terminal window, by typing the plus sign (+) three times.

Note

Do not press the ENTER key after the +++ command. It may cancel the command.

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Motorola SM56 manual