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6 Basic Modem Operation
The next window sets the COM port settings. The settings used for the Comet should
be as follows:
Bits per second: 115200
Data bits: 8
Parity: None
Stop bits: 1
Flow Control: Hardware
Click
“
OK
”
when finished. After you have done this, save your new connection by
selecting
“
Save
”
from the
“
File
”
menu and click
“
OK.
”
A new connection icon will be
added to your Hyper Terminal folder.
You are now ready to start entering AT commands.
In the terminal window, type:
AT<Enter>
Comet responds
OK
This confirms that the modem and your computer are communicating correctly.
To test the telephone line connection issue the manual answer command.
Type:
ATA<Enter>
The Comet will pick up the phone line, and try to communicate. Normally, this
command is only used to answer an incoming call made from another modem. Thus
the high pitched noise you will hear from the speaker. To abort the operation, press
any key, or select
“
Disconnect
”
from the
“
Call
”
menu.
Dialing and Answering Techniques
Depending on what communications software you use to make modem connections,
you may not have as much control of how the modem dials the telephone number. This
section shows some useful examples of the AT commands used for dialing and
answering operations. The command characters specific to each function are shown in
bold type.
Dialing using the ATD Command
Touch Tone Dialing: ATD
T
555 1212
Pulse Dialing: ATD
P
555 1212
Tone and Pulse Dialing: ATD
P
555 1212 W
T
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