Paradyne 3800PLUS manual AT Command Set and 13 S-Registers, Operating Modes, Type +++, Overview

AT Command Set and 13 S-Registers

Overview	13-1
Operating Modes	13-1
Switching Between Data Mode and Online Command Mode	13-1
Command Guidelines	13-2
AT Command List	13-2
AT Command Format	13-5
S-Register List	13-14
S-Register Format	13-14

Overview

The AT command set provides an alternative method to the front panel for entering commands that control the operation and configuration of the 3800Plus modems.

AT commands are issued from an asynchronous DTE (such as a personal computer). This chapter explains how to use AT commands and lists the modifiers for all

AT commands supported by the 3800Plus modems.

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.

Operating Modes

The 3800Plus 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.

In Command mode, any command issued is acknowledged with a response in either words or digits known as a result code. Refer to Appendix B for a list of result codes.

Once the modems go 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.

Escape Sequence and Escape Guard Time

The escape sequence is only issued when the modem is online and in Data mode. The 3800Plus modem uses three consecutive plus (+) characters as the escape sequence.

(To change this value, refer to S-register S2 discussed later in Table 13-2 in the S-Register Format section.)

To prevent the modem from interpreting an embedded

+++in data as an escape sequence, the Escape Guard Time value determines the length of the pause before and after the escape sequence is issued. The 3800Plus modem uses a one second pause as the Escape Guard Time. (To change this value, refer to S-Register S12 discussed later in Table 13-2 in the S-Register Format section.)

To enter online Command mode while in Data mode, enter the following sequence:

TYPE: +++

3980-A2-GB30-20 November 1996 13-1