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Appendix B: AT Command Set
AT Commands
AT commands are issued to the modem to control the modem’s operation and soft-
ware configuration. AT commands are commonly entered from a terminal program
such as HyperTerminal, and can only be entered while the modem is in command
mode. To enter an AT command, type:
ATXn
where X is the AT command, and n is the specific value for that command. Press
ENTER.
Commands are acknowledged with either text or numeric value response known as a
result code. In the case of multiple AT commands on the same command line, the
commands are executed in the order they are received. Should execution of a com-
mand result in an error, or a character not be recognized as a valid command, execu-
tion is terminated, the remainder of the command line is ignored, and the ERROR
result code is issued. If all commands execute correctly, only the result code associ-
ated with the last command shall be issued, even though all have been executed.
In the following listing all commands and command values accepted by the modem
are shown. Any entries other than those shown cause the ERROR result code.
+++
Escape sequence
The escape sequence allows the modem to exit data mode and enter on-line com-
mand mode. While in on-line command mode, you may communicate directly to
your modem using AT commands. Once you are finished, you may return to data
mode using the ATO command. A pause, the length of which is set by the Escape
Guard Time S-Register (S12--See the “S-Registers Reference” section of this manual
for details), must be used after an escape sequence is issued. This pause prevents the
modem from interpreting the escape sequence as data. The value of the escape se-
quence character may be changed using Register S2.
A/
Repeat Last Command
This command repeats the last command string entered. Do not precede this com-
mand with an AT prefix or conclude it by pressing Enter.
A
Answer Command
This command instructs the modem to go off-hook and answer an incoming call.
Summary of Contents for Plug n' Play Voice/Fax Modem V.90 ISA
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