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5-13910-A2-GN32-30 November 1996
AT Command Set and S-Registers
Overview 5-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating Modes 5-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Switching Between Data Mode and Online Command Mode 5-1. . . . . . . . .
Escape Sequence and Escape Guard Time 5-2. . . . . . . . . . . . . . . . . . . . . .
Command Guidelines 5-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Result Codes 5-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
AT Command List 5-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
AT Command Format 5-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
S-Register List 5-14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
S-Register Format 5-15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Overview
The
A
T command set provides an alternative method to the modem’s DCP for entering commands
that control the operation and configuration of the 391x Series modems. This chapter discusses
guidelines necessary to operate A
T commands as well as listing the modifiers for all AT commands
supported by the 391x Series modems. A
T commands are issued from asynchronous DTEs.
Operating Modes
The
391x Series modem has two operating modes, Command mode and Data mode. Before a
modem goes online (establishes a successful connection with a remote modem), it is considered to
be in Command mode; an idle state where you can modify its operating parameters or issue
modem commands. (Any command issued is acknowledged with a response in either words or
digits known as Result Codes. Refer to T
able 5-1 for a listing of result codes.)
Once the modems are online, either by answering or originating a call, they automatically switch to
Data mode. Data mode is a state where any entries made from the DTE are considered data and are
transmitted and received between modems. The modems remain in Data mode until the connection
is broken or until they are forced into online Command mode using the escape sequence.
Switching Between Data Mode and Online Command Mode
Sometimes
it is necessary to change operating parameters while the modems are online. The
Escape Sequence allows you to toggle the modem between Data mode and online Command mode
while maintaining a connection with the remote modem. This is accomplished using the escape
sequence ( + + + ) to exit Data mode and the O command to return to Data mode.
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