Multi-Tech MultiModem ISIHI-2S, Руководство пользователя

Страница: 92 / 186

92 MultiModemISI Hybrid Series, ISIHI-2S
Chapter 5—TERMINAL ADAPTER AT Commands, S-Registers, Result Codes
T
erminal Adapter
Terminal Adapter AT Commands
One of the ways you can communicate with and configure your terminal adapter (TA) is
to use AT commands. AT commands are so-called because, with only a few exceptions,
each command string begins with the characters
AT. Using AT commands, you can read
and set parameters and perform actions such as dialing.
Entering AT Commands
You can send AT commands to the TA by entering them on the keyboard, by typing them
in the terminal window of a data communications program such as HyperTerminal, or
indirectly by configuring your data communications program.
Enter AT commands in the following format: AT <command string> <cr>. The AT
characters cause the TA to interpret the following string of characters as a command. The
command string consists of one or more commands. The carriage return character, <cr>,
sends the command string to the TA. If you are entering a command string in your
communication program’s terminal window, insert the carriage return character by
pressing ENTER. On the other hand, if you are configuring a communications program,
you typically must insert the carriage return character by adding ^M to the end of the
command string.
The TA has three modes of operation: offline command mode (the default state), online
command mode, and data mode. The TA responds to AT commands only when it is in
one of the command modes. After the TA establishes a connection and goes online in
data mode, it interprets any further characters you enter as data rather than commands
and transmits them to the remote device.
When the TA is in data mode, you can switch it to online command mode by sending it an
escape sequence. The TA responds to two types of escape sequences: in-band (escape
sequence is part of the data stream) and out-of-band (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 TA enters online command mode, in which it
responds to commands while maintaining the connection with the remote device.
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 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.
AT commands recognized by the ISIHI-2S terminal adapter are listed by function on the
following page. For an alphabetic list of AT commands, see
AT commands in the index.
The commands in this chapter are organized by function. Abbreviated commands are
listed on the following page by function along with a short description and page numbers
that refer to a more detailed description, immediately following this list.