D-Link ENW-3503, User Manual

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3. MODEM BASICS
PLANET ENW-3503 User's Manual 3-1
3. MODEM BASICS
This chapter covers the basic commands and techniques
involved in modem operation. In many cases, this is the only
information you will need in order to get your ENW-3503 PC
Card up and running with communication software, and to
start making connections with your PC Card.
3.1 Understanding AT Commands
The ENW-3503 PC Card communicates asynchronously with
computers using AT commands. AT commands are used to
configure and control the PC Card. Commands are usually
sent to the modem in way of communication software, but can
also be entered manually with the computer keyboard.
Command statements must be written in a specific form in
order for the ENW-3503 PC Card to recognize them. A
command statement always begins with the letters
AT or at . It
is then followed by one or more commands and the <Enter>
key.
AT commands can only be issued when the ENW-3503 PC
Card is in “command mode” or “off-line.” Once the PC Card
has established a connection with another modem, it is said to
be “on-line” or in “data mode.” In this mode, the characters
sent to the E Fax/Modem PC Card by your computer
are transmitted to the remote modem rather than being
interpreted by the PC Card as commands.
Using the Windows 95 Hyper Terminal Program
To issue an AT command statement, you first need to run a
communication program such as the Microsoft Windows
“Hyper Terminal” program. This program provides a simple
method to manually enter AT commands so you can do such