Multi-Tech Systems MTA128NT 用户手册

All references to “TA” in this chapter refer to the MTA128ST/NT. This chapter also assumes knowledge of
issuing AT commands. <

CR> refers to the carriage return character (typically generated by pressing the

ENTER or RETURN key on the keyboard).

For command execution details see the additional documents on this CD.

The TA’s command buffer can store 80 characters, including spaces and other characters used in
telephone numbers. If you mistype a command string, you can edit it by using the backspace or the delete
key, but only before you press 

<CR>. As you type a command string, it appears on your monitor screen,

letting you verify your input as you type it. The table below lists the AT commands recognized by the TA.

If your MTA128ST/NT is connected to a computer terminal, you can send AT commands to the MTA128ST/
NT by entering them on the keyboard. If your MTA128ST/NT is connected to a computer, you can send AT
commands to the MTA128ST/NT by typing them in the terminal window of a data communications program
such as HyperTerminal. You can also send some AT commands indirectly by configuring your data
communications program.

To enter AT commands, use the following format: 

AT <command string> <cr>. The characters AT cause

the MTA128ST/NT to interpret the following string as a command. The command string consists of one or
more commands. The carriage return character, <cr>, sends the command string to the MTA128ST/NT. If
you are entering a command string in your communication program’s terminal window, insert the carriage
return character by pressing the ENTER key on your keyboard. If configuring a communications program,
you typically must insert the carriage return character by adding ^M to the end of the command string.

The MTA128ST/NT has three modes of operation: offline command mode (the default state), online
command mode, and data mode. The MTA128ST/NT responds to AT commands only when it is in one of
the command modes. After the MTA128ST/NT establishes a connection and goes online in data mode, it
interprets any further characters you enter as data rather than as commands and transmits them to the
remote device.

When the MTA128ST is in data mode, you can switch it to online command mode by sending it an 

escape

sequence. The MTA128ST/NT responds to two types of escape sequences:

•

In-band where the escape sequence is part of the data stream.
The in-band escape sequence is 

+++AT<cr>. To change the in-band escape character (+),

change the value in register 

S2.

•

Out-of-band where the escape sequence is outside the data stream. The out-of-band escape
sequence is 

<break >AT<cr>. You can send the break signal in the out-of-band escape sequence

only from software, 

not by pressing SHIFT+BREAK on your keyboard.

When it detects the escape sequence, the MTA128ST/NT enters online command mode where it responds
to commands while maintaining the connection with the remote device.

The MTA128ST/NT’s command buffer can store 80 characters, including spaces and other characters
used in telephone numbers. If you mistype a command string, edit it by using the backspace or the delete
key but only before you press ENTER. As you type a command string, it appears on your monitor screen,
letting you verify your input as you type it.

The AT commands recognized by the MTA128ST/NT are listed by function in this chapter first in an
abbreviated list. For an alphabetical list of AT commands, see the AT commands documents on the CD
included with this product.