Multitech RASFinder RF300E, User Manual

Page: 121 / 199

Appendix D - AT Command Summary
RF300E/RF310E 121
Appendix D - AT Commands
One of the means by which you can communicate with and configure your RASFinder is to use AT
commands. AT commands are so-called because, with only a few exceptions, each command string
must begin with the characters AT. Using AT commands, you can read and set parameters, and
perform actions such as dialing.
Entering AT Commands
If your RASFinder is connected to a computer terminal, you can send AT commands to the
RASFinder by typing them on the terminal keyboard. If your RASFinder is connected to a computer,
you can send AT commands to the RASFinder 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.
Enter AT commands in the format AT <command string> <CR>. The characters AT cause the
RASFinder 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 RASFinder.
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 you are configuring a
communications program, on the other hand, you typically must insert the carriage return character
by adding “^M” to the end of the command string.
The RASFinder has three modes of operation: offline command mode (the default state), online
command mode, and data mode. The RASFinder responds to AT commands only when it is in one of
the command modes. After the RASFinder 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 RASFinder is in data mode, you can switch it to online command mode by sending it an
escape sequence. The RASFinder responds to two types of escape sequences: in-band, in which the
escape sequence is part of the data stream, and out-of-band, in which the escape sequence is
outside the data stream. The in-band escape sequence is +++AT<CR>; the out-of-band escape
sequence is <Break >AT<CR>. You can change the in-band escape character (+) by changing the
value in register S2. 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 RASFinder enters online command mode, in which it
responds to commands while maintaining the connection with the remote device.
The RASFinder’s command buffer can store 80 characters, including spaces and other characters
used in telephone numbers. If you mis-type a command string, you can 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.