Rs-232 Requirements - US Robotics COURIER User Manual

COURIER HIGH SPEED MODEMS
•
Follow the operating instructions in Appendix E, Dedi-
cated Line and Leased Line Operation,
if your phone line is
user-installed or if it is leased from the telephone
company. Also referred to as private, these lines are
used for a direct, continuous connection between two
modems. The connection is made without dialing.
• If your modem is installed in a Hewlett Packard system
that uses the Ack/Enq communications protocol, be sure
to follow the instructions at the end of Appendix E.
• If the modem is attached to a computer instead of a
terminal, you need communications software. The
software uses the modem's AT command set to control
many communications functions, including configuring
the modem, dialing, and answering calls, and also
enables the transfer of files and other operations.
Some users prefer their communications software to take
control of the modem, and are more comfortable with a
program that makes the modem almost transparent.
Others prefer a program that allows them to use the
modem's AT command set sometimes, and their soft-
ware at other times, depending on the task at hand.
Whichever you prefer, review at least the Quick Start
(Chapter 3) so that you have a basic understanding of
the modem's requirements and operation.
RS-232 Requirements
You'll need an RS-232 cable to connect the modem to your com-
puter or terminal. Use a shielded cable to ensure minimal inter-
ference with radio and television reception.
The modem takes a DB-25P (25-pin plug, or male) connector at
one end of the cable. Computer equipment varies, however.
Check the serial port at the rear of your machine, which may be
labeled
SERIAL, COMM PORT,
or some other term (e.g., RS-232). If
there are no labels, review your machine documentation to find
out which is the serial port. (There may be more than one.)
Don't use a port marked
PARALLEL, PRINTER
or
AUX.
The physical serial port on the computer or terminal will be
either a socket (female) or plug (male) that typically accom-
modates 25 or 9 pins. For example, the port on the IBM PC,
PC/XT and most compatibles requires a DB-25S (socket) con-
2-2 Set-up and Testing
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