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PN 88300150
3.6
Command Mode Fundamentals
This section discusses Command Mode fundamentals, Dialing commands, Immediate Action commands
(except dialing), and Configuration commands. The rest of the commands are covered in Chapter 5.
3.6.1 Entering and Executing Commands
When you type commands for the MT2834MR, each command must start with the Attention Characters
AT. Attention characters can be typed in either upper case (capital) or lower case (small) letters.
The AT characters alert the modem that a command follows. The Attention command can also be used to
clear the command buffer, by typing AT and then hitting ENTER.
Typing the AT characters automatically sets the modem's speed to match the speed of your computer or
terminal, and also sets the modem's parity.
The MT2834MR will not execute a command until you hit ENTER. Therefore, ENTER should be pressed
when the entire command has been typed. There are some exceptions to this rule. The A/ (Repeat Last
Command) command is executed without hitting ENTER. The A: command is also executed without
hitting ENTER.
Typing A/ will cause the MT2834MR to repeat the last command that was executed. This last command
remains stored in the modem's command buffer until the Attention Command AT is typed. Therefore, AT
must not be typed before A/ is typed. The A/ command will have no effect if there is no command stored
in the command buffer. It is not necessary to hit ENTER to execute this command.
Many MT2834MR commands consist of a letter, followed by a number (0, 1, etc.). If a command like this
is typed without the number, the modem will assume that its value is zero (0). For example, if you type
ATH as a command without a 0 or 1 following the H, the command will be ATH0. (In this example, the
effect is that the modem hangs up.) As you become more familiar with the MT2834MR's commands, you
will find yourself taking advantage of this shortcut.
3.6.2 Command Editing
You can use the BACKSPACE key on your keyboard to edit characters in the command line. The
command will not be executed until you hit ENTER. The BACKSPACE key erases the previous character
for retyping.
The BACKSPACE key will not erase the AT characters once they are typed. If your keyboard has no
BACKSPACE key, CTRL-H will accomplish the same thing. The character recognized by the modem as
BACKSPACE may be changed to any other ASCII character with S-Register S5.
To cancel an entire command that has been typed but not yet executed, type CTRL-X. This also clears
the command buffer. The effect is the same as backspacing to cancel the entire command, only quicker.
Characters typed in a command are stored in the MT2834MR's Command Buffer (memory) until executed
by hitting ENTER. The Command Buffer's capacity is sixty characters. The Attention Characters AT do
not count in the sixty allowed Command characters. Spaces, which may be used for increased display
readability, may be used when typing a Command, but are not stored in the Command Buffer and are not
counted in the sixty allowed characters. Hyphens, parentheses etc., are not allowed.
If the sixty character limit is exceeded or if invalid characters are typed, the Command Buffer is
automatically erased, and an ERROR message appears. You then retype the command within the sixty-
character maximum, using only the allowed characters.
Note:
In some applications, such as auto-answer only, you may disable the Command mode altogether.
When you do this, the MT2834MR ignores all commands, and functions as an auto-answer non-intelligent
modem. This is done with DIP-Switch #8 on the modem card (explained in Chapter 7). The factory default
setting is Command mode enabled.
4/3/01
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