Actiontec electronic V.90 manual Appendix a AT Command Set, +++Atcr, Registers

Appendix A: AT Command Set

AT Commands

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 text format known as result codes. For multiple AT commands in the same command line, the com- mands are executed in the order received from the DTE. Should execution of a command result in an error, or a character not be recognized as a valid command, execution is terminated, the remainder of the command line is ignored, and the ERROR result code is issued. Otherwise, if all commands execute correctly, only the result code associated with the last command shall be issued; result codes for preceding commands are suppressed.

In the following listing, commands and command values accepted by the modem are shown; any entries other than those shown cause the ERROR result code. AT Commands may be entered in upper or lower case letters but you should not mix upper case and lower case letters within the same command line.

+++AT<CR> 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. If you are in data mode and wish to enter com- mand mode, you must type the escape character (the value stored in S2, typically “+”) three times followed by a valid AT Command and the carriage return charac- ter specified by S-Register S3 (typically <enter>). Using the default values of S2 and S3, the escape sequence would be like this: +++at<enter>

S-Registers

S-registers generally affect how the AT commands perform. Contents of the regis- ters can be displayed or modified when the modem is in command mode.

To display the value of an S-register:

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