1-10
AT COMMANDS AND S-REGISTERS
AT commands are issued to the modem to control the modem's
operation and software configuration. AT commands can only be
entered while the modem is in command mode. The format for
entering AT commands is:
TYPE:
ATXn
where
X
is the AT command, and
n
is the specific value for that
command.
PRESS:
Enter
Any command issued is acknowledged with a response in either
text or numeric values known as result codes. The Result Code
Options Tables in Appendix C list all the valid result codes.
All commands and command-values accepted by the modem, the
OK
message will be shown; any entries other than those show OK
response cause the
ERROR
result code.
This chapter describes how to use the AT commands for the users
who need special parameters in order to meet their applications.
Refer to the appendix for the detailed AT command definition.
How to Use AT Commands
Usually, your fax and data communications software controls the
modem for you. However, you may also want to use the AT
commands. These commands give you complete control over your
modem. Using the AT commands carefully every time, because
they can cause your software to loose its ability to control the
modem. When you do find any AT command causes fax/modem
maul-function, turn the computer off and then on. That will reset
most of the AT command settings to the factory defaults.
In order to use an AT command, you need to have done the
following:
1.
Run your communication software.
2.
Configure the software for the appropriate COM port and
IRQ setting if necessary.
3.
Enter terminal mode (aka command mode, local mode, or
direct mode.). This is usually the mode that communications
software starts up. Then, type the AT command you need,
then press
Enter
key. For example,
