3Com 2940, 2941 User manual

This manual covers installation and operating instructions for the following 3Com®modems:
U.S. Robotics®Cable Modem CMX 3CR292-DE56 (model 2940)
U.S. Robotics®Cable Modem CMX 3CR292-DE40 (model 2941)
3Com, the 3Com logo, U.S. Robotics, the U.S. Robotics logo, EtherLink, and OfficeConnect
are registered trademarks and Connections is a trademark of 3Com Corporation. Windows is a
registered trademark of Microsoft Corp. Macintosh is a registered trademark of Apple
Computer, Inc. Any other trademarks, trade names, or service marks used in this manual are the
property of their respective owners.
Copyright © 1999 3Com Corporation
3800 Golf Road
Rolling Meadows, IL 60008
All Rights Reserved

TABLE OF CONTENTS
Introduction 1
Cable Modem Features 1
Before You Begin 3
Contacting Your Local Cable Company 3
Preparing Your Workspace 5
You Will Need These Items 5
Configuring the TCP/IP Protocol on a Windows PC 6
Configuring the TCP/IP Protocol on a Macintosh PC 8
Hardware and Software Installation 11
Wall-Mount Installation 11
Desktop Installation 13
OfficeConnectStackingInstallation 13
Connecting the Cable Modem to Your Computer 15
Installingthe CableConnectionsCD-ROM 18
Cable Modem Operation 19
Troubleshooting and Support Resources 23
Support Resources 25
If You Are Still Having Problems 26
If You Need to Return the Modem to Us 26

Regulatory Information and Limited Warranty 29
Manufacturer’s Declaration of Conformity 29
3Com Corporation Limited Warranty 32

INTRODUCTION
1
Congratulations! You have just purchased a
modem that features a pioneering new
technology. 3Com, a leader in networking
and data access, is proud to offer you this
technology that makes Internet access
possible at speeds previously only
imagined!
This external cable modem is one part of a
comprehensive communications system that
utilizes the cable television network to
deliver high-speed data to your computer.
Data is requested and sent over the cable
television network at burst rates of up to 38
megabits per second (Mbps).
Cable Modem Features
•User data rates of up to 3000K,* faster
than 56K analog modems, ISDN, or
ADSL
•Two-way design means that the CMX
sends and receives data over the cable
line (unlike one-way modems, which
require an analog modem for upstream
data)
•Plug and play operation ensures easy
setup and installation
•DOCSIS-compliant for interoperability
with cable operators
•3Com’s extensive user support
organizations and our 5-year limited
warranty
* Please note that the following factors
affect the speeds you may experience:
•Your computer equipment and
configuration, including the speed of
your processor, the amount of RAM on

I
NTRODUCTION
2
your system, and your available hard
disk space.
•The Internet browsing, e-mail, or other
programs you run at the same time,
which use your computer’s resources.
•The capacity of the Internet service you
order from your provider.
•Changing network traffic levels
depending when you go online.

BEFORE YOU BEGIN
3
This chapter explains how to prepare your
computer system for cable modem
installation.
Contacting Your Local Cable
Company
In order to use your cable modem, you need
to establish an Internet access account with
your local cable company. Before
contacting your cable company to establish
an account, have the following information
handy:
•The modem’s Media Access Control
(MAC) address (located on a bar code
sticker on the back of the modem). The
MAC address consists of 12 characters
preceded by the text EA =. In the
following example label image, the
MAC address is 00104B377410. Write
the MAC address in the blank provided
below.
•The modem’s model number (located
on a sticker on the bottom of the
modem). Your modem’s model number
will be 2940 or 2941.
MAC address: EA = __________________
Model number (circle one): 2940 or 2941

B
EFORE
Y
OU
B
EGIN
4
You should now contact your local cable
company and verify the following:
•You have cable service to your home
that supports two-way cable modem
access. If your cable company does not
provide two-way service, the
U.S. Robotics Cable Modem CMX will
not be able to communicate with your
cable company’s Internet access service.
You should immediately consult your
cable company and place of purchase to
determine the proper U.S. Robotics
cable modem that will work with your
cable company. You can also visit the
following URL for additional
information:
http://www.3com.com/cablemodem
•Your cable company has set up your
cable Internet access account. Your
cable company will establish an Internet
access account that will allow you to
send and receive e-mail, access the
World Wide Web, and receive other
Internet services. This account must be
established before you can use your
cable modem.
•You have a cable line near your PC
and it has been prepared for cable
modem service. If you do not have a
cable line in your home that supports
two-way cable modem access or if your
current cable connection is not
conveniently located near your
computer, your cable company can
install one. If you use your cable line for
cable television access, your cable
company can also install an additional
line for use with your cable modem.

B
EFORE
Y
OU
B
EGIN
5
Preparing Your Workspace
•Position your computer so that it is
located near your cable outlet.
•The cable modem should be located near
your computer and the cable outlet.
There should be plenty of room to guide
the cables away from the modem without
crimping the cables.
•The modem should be located where it
has ample space to allow constant
airflow around the unit.
•Do not stack anything on top of the cable
modem. (See the instructions on page 13
concerning stacking this modem with
3Com OfficeConnect products.)
•The temperature in the room where the
cable modem will be operating should be
between 0 and 40°C (32 and 104°F).
Relative humidity should be between 5
and 95%, non-condensing.
•Familiarize yourself with all of the
materials in this box. Please read these
installation instructions thoroughly
before installing your cable modem.
CAUTION: Your cable company
will provide a cable connection. Do not
attempt any rewiring without first
contacting your cable company.
You Will Need These Items
Included:
•Cable modem
•Cable modem power supply
•RJ-45 network cable
•Rubber feet and stacking clips kit
•Cable ConnectionsCD-ROM

B
EFORE
Y
OU
B
EGIN
6
•Fold-out Quick Installation Guide
•This User’s Guide & Reference
Not Included:
•A PC running Windows95 (or later)
or a Macintoshrunning System 7.5 (or
later) with TCP/IP protocol installed
(see the following two sections for more
information on installing TCP/IP)
•An active two-way cable line
•An active Ethernet port or network
interface card (NIC) installed in your
computer
•A 7/16 inch (or adjustable) wrench for
securing the cable line to the modem
•A screwdriver, pushpins, and screws (for
optional wall-mounting) The screw
heads should be at least 0.2” (5mm) in
diameter for them to be properly
captured in the slot. If you are using
wood screws, use #6 pan heads or
equivalent.
Configuring the TCP/IP
Protocol on a Windows PC
If you have a PC running Windows 95 or
later, you need to make sure the TCP/IP
communications protocol is installed on
your system before you install your cable
modem. The listing of actual components
installed on your PC depends on the
hardware installed in your computer. The
installation example in this guide assumes a
3Com EtherLinkIII 3C509B-TPO NIC
has been installed and the screen images
shown below reflect this hardware
configuration. Other networking cards will
work but the screen images will look
somewhat different.

B
EFORE
Y
OU
B
EGIN
7
NOTE: If you need to install a
network interface card to give your
computer Ethernet capability but have
not yet done so, perform this operation
first by consulting your NIC installation
manual and then return here to
complete installation of the TCP/IP
software.
1. Click Start, point to Settings, and then
click Control Panel.
2. Double-click the Network icon.
3. A list of installed network components
appears. Look for an entry that includes
TCP/IP -> followed by the NIC
hardware device installed in your
computer. (The entry for the 3C509B-
TPO example is shown in the following
screen image).
If an entry similar to this is present, go to
step 9 on the next page.
4. If a similar entry is not present, click
Add...
5. Click Protocol, and then click Add...
6. Click Microsoft in the “Manufacturers:”
list and then click TCP/IP in the
“Network Protocols:” list. Click OK.