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.

B
EFORE
Y
OU
B
EGIN
8
7. “TCP/IP” will appear in the list of
installed network components. Click
OK.
8. Windows will now ask you if you would
like to restart your computer. Click No.
9. Your cable companymayprovide you
with additional TCP/IP setup
instructions. Consult those instructions,
if provided, to complete configuration of
your PC to work with your cable
modem. When you are finished, turn to
“Hardware and Software Installation”
(page 11).
Configuring the TCP/IP
Protocol on a Macintosh PC
You will need to configure TCP/IP to work
with your cable modem if you are using a
Macintosh.
1. Double-click your Systemfolder.
2. Double-click Control Panels.
3. Look for the TCP/IPControl Panel
icon.

B
EFORE
Y
OU
B
EGIN
9
If you do not see this icon, you must
reinstall your Macintosh system
software and add networking support.
Consult your Macintosh User Manual
for more information on how to do this.
4. Exit out of all open windows.
5. Your cable company may provide you
with additional TCP/IP setup
instructions. Consult those instructions,
if provided, to complete configuration
of your Mac to work with your cable
modem. When you are finished, turn to
“Hardware and Software Installation”
(page 11).

B
EFORE
Y
OU
B
EGIN
10

HARDWARE AND SOFTWARE INSTALLATION
11
NOTE: Before installing your
modem, write its serial number in the
space provided on the first page of this
manual. (You’ll find the serial number
above the bar code on the white sticker
on the back of the modem and on the
outside of the modem’s box.) If you
ever call our customer support
department, a representative will ask
you for the serial number. This will
help to identify your modem.
Before you begin installing the cable
modem hardware, you need to determine
how you want to incorporate the modem
into your work environment. There are
three installation options:
1. Wall-mount installation (this page)
2. Desktop installation (page 13)
3. OfficeConnect stacking installation
(page 13)
Wall-Mount Installation
Your cable modem is capable of being wall-
mounted, if you choose to do so. The
bottom panel of the cable modem has two
raised brackets with slots as shown in the
following illustration.
NOTE: Before wall-mounting the
cable modem, follow the instructions in
the section “Connecting the Cable
Modem to Your Computer” (pages 15-
18). Then return to this point to
continue the process.

H
ARDWARE AND
S
OFTWARE
I
NSTALLATION
12
mounting
holes
®
These slots fit over the heads of wall-
mounting screws to secure the modem to
the wall. A mounting template for marking
the location of the mounting screws is
included in the foldout Installation Guide
that accompanies this manual.
1. Remove the mounting template from the
Installation Guide.
2. Place the mounting template against the
wall at the location chosen for the cable
modem. The template should be parallel
to and at least 20 inches (50 cm) from
the floor. Insert pushpins through the
template cross hairs into the wall to mark
the locations for the screws.
3. Secure the mounting screws into the
wall. Do not drive the screws flush to the
wall. The screw head should be at least
¼” (6 mm) away from the wall so it can
lock into the slots on the modem’s case.
4. Fit the slots in the brackets on the
modem’s underside over the screw heads
and let the modem slide down into
position.

H
ARDWARE AND
S
OFTWARE
I
NSTALLATION
13
20"
[ 50 cm ]
INSTRUCTIONS FOR WALL-MOUNTINGTHE CABLE MODEM
Wall-mounting Template
See other side for basic instructions.
For complete instructions, see the
User's Guide & Reference
.
®
If you have not already done so, turn to
“Connecting the Cable Modem to Your
Computer” (page 15). Otherwise, turn to
“Installing the Cable Connections
CD-ROM” on page 18.
Desktop Installation
If you plan to place your modem on a flat
surface, you can use the four self-adhesive
rubber feet included in your modem’s
package to prevent your modem from
sliding around. Stick the feet to the marked
areas at each corner of the underside of your
modem. Turn to “Connecting the Cable
Modem to Your Computer” (page 15).
OfficeConnect Stacking
Installation
If you own 3Com OfficeConnect products,
you can use the four stacking clips included
in your modem’s package to neatly and

H
ARDWARE AND
S
OFTWARE
I
NSTALLATION
14
securely stack your cable modem with the
OfficeConnect unit(s). If possible, your
cable modem should always be the top unit
in a stack with OfficeConnect products.
Small hubs are the only units that should be
clipped to the top of a cable modem. Follow
these instructions to clip your modem to an
OfficeConnect unit.
1. Place the OfficeConnect device you
want at the bottom of the stack on a flat
surface. The supplied blue clips fit in the
positions on the side of the unit as shown
in step 1 of the illustration on the next
page.
2. Position a clip over one of these holes
and push it in until it clicks into place, as
shown in step 2 of the illustration on the
next page. Repeat this for the other clip
position on the same side.
3. Keeping the front of the units aligned,
position the top-most OfficeConnect
device and rest the bottom of the device
on the clips' spikes, as shown in step 3 of
the illustration on the next page. Push
the clips firmly until they click into
place.
NOTE: To remove a clip, hold the
units firmly with one hand and hook the
first finger of your other hand around
the back of the clip. Be careful not to
pull so hard that you break the clip.
4. Repeat these steps to secure the other
side.
5. Turn to “Connecting the Cable Modem
to Your Computer” (page 15).

H
ARDWARE AND
S
OFTWARE
I
NSTALLATION
15
Connecting the Cable Modem
to Your Computer
TIP:Before you unplug any cords,
label them or make a sketch of how
they are connected. This can be helpful
when you plug them back in later.
CAUTION:To avoid risk of
electric shock, make sure your
computer and all peripheral devices are
turned off and unplugged from
electrical outlets.

H
ARDWARE AND
S
OFTWARE
I
NSTALLATION
16
NOTE: Refer to the diagram on the following page while following these steps.
1. Turn off your computer and unplug it from the electrical outlet.
2. Using the following illustration as a guide, make the following connections:
•Connect your cable line to the cable modem’s CATV cable connector. Be careful not to
bend the wire in the center of the cable line when you connect it to the cable modem.
After hand-tightening the CATV cable connector, use your 7/16 inch or adjustable wrench
to firmly tighten the connector. Be careful not to over-tighten the connector or you might
damage the connector or your cable modem.
•Plug the cable modem’s power supply into a wall socket or surge protector and into the
cable modem’s power jack (labeled with a graphic that looks like this:
-+
).
•Plug one end of the RJ-45 network cable into the cable modem’s RJ-45 jack and the other
end into the existing network interface card installed in your computer.
•The serial port on your cable modem is unused during two-way operation. If the cable
modem is being used with an analog modem for telephony-return cable modem operation,
you will receive additional instructions on how to make these connections.
3. Verify that your cable modem starts up and initializes properly. You can tell that your
modem is operating properly if the Cable Modem Power and Cable Modem Status LEDs

H
ARDWARE AND
S
OFTWARE
I
NSTALLATION
17
are lighted solid green. If you are powering up your cable modem for the first time, allow 5
to 15 minutes for this process to complete. Consult the chapter titled “Cable Modem
Operation” for a more in-depth description of the front panel LED indicators.
CATV
SERIAL 10 BT
cable line (to cable
outlet) RJ-45 Cable
power supply
(to wall outlet)
RJ-45 cable
(to NIC)
4. Plug the computer’s power cord back into the computer. Turn on the computer. When
installation is complete, your setup should resemble the following diagram.