User manual

Section 3

BEFORE YOU START

3-3

3.7 Escape Sequence

While off-line, the DPX-213 is in the Command State and all characters typed at your

keyboard are scanned by the command interpreter awaiting AT commands. Once on-line,

whatever is typed is sent to the remote modem. In order to get back in touch with the local

command interpreter, perhaps to hang up or to change parameters, an escape sequence

must be sent.

The industry standard "+++" escape sequence does not hang up the line or interfere with

other settings and is entered by pausing for a few seconds, typing

+++

, and then

pausing again. Do not press

(Carriage Return or Enter). Typing the escape sequence

returns you to the On-line Interactive State where the AT commands are active. For

example, typing

athK

will hang up the call.

3.8 Advanced Features

The DPX-213 has MNP-4 error correction and MNP-5 data compression software. These

are disabled in the factory defaults and must be specifically enabled if required. The

Constant Speed Interface is active by default and allows terminal speeds from 300 to 9,600

bps to be automatically supported. The modem will normally attempt to establish all calls

at 2,400 bps unless commanded otherwise or the remote modem cannot support this speed.

The modem automatically adjusts the transmit or receive speed to match the modem at the

other end of the link. The line speed of the connection is displayed as the modem goes on-

line.

The Constant Speed Interface facility, error correction and data compression are powerful

features, but can result in problems if your terminal does not support flow control. If you

are obtaining errors, or characters are garbled or missing whenever these features are

invoked, it is likely there is a flow control problem. Check your communications software

manual, the flow control sections (see Index) and the relevant AT commands of this

manual.

To reduce the risk of unauthorised entry to your system, the DPX-213 features password

verification. A password may be stored in the DPX-213 permanently and only those calls

meeting the incoming password challenge are allowed access to the host.

The DPX-213 also contains an alarm feature that will dial a remote modem when an

external device indicates that an event has occurred. The modem will connect with the

remote modem and attempt to send a previously stored string.