3COM 2940, 2941 User Manual

6.7 Mb

This manual covers installation and operating instructions for the following 3Com® modems:

U.S. Robotics® Cable Modem CMX3CR292-DE56(model 2940)

U.S. Robotics® Cable Modem CMX3CR292-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




Cable Modem Features


Before You Begin


Contacting Your Local Cable Company


Preparing Your Workspace


You Will Need These Items


Configuring the TCP/IP Protocol on a Windows PC


Configuring the TCP/IP Protocol on a Macintosh PC


Hardware and Software Installation


Wall-Mount Installation


Desktop Installation


OfficeConnectâ Stacking Installation


Connecting the Cable Modem to Your Computer


Installing the Cable Connectionsä CD-ROM


Cable Modem Operation


Troubleshooting and Support Resources


Support Resources


If You Are Still Having Problems


If You Need to Return the Modem to Us


Regulatory Information and Limited Warranty


Manufacturer’s Declaration of Conformity


3Com Corporation Limited Warranty



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-speeddata 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-waydesign means that the CMX sends and receives data over the cable line (unlikeone-waymodems, which require an analog modem for upstream data)

Plug and play operation ensures easy setup and installation

DOCSIS-compliantfor interoperability with cable operators

3Com’s extensive user support organizations and our 5-yearlimited 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



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.


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


This chapter explains how to prepare your computer system for cable modem installation.

Contacting Your Local Cable


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:

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 or2941.

MAC address: EA = __________________

Model number (circle one): 2940 or 2941



You should now contact your local cable company and verify the following:

You have cable service to your home that supports two-waycable 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:


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.


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


Cable modem

Cable modem power supply

RJ-45network cable

Rubber feet and stacking clips kit

Cable ConnectionsCD-ROM



Fold-out Quick Installation Guide

This User’s Guide & Reference

Not Included:

A PC running Windowsâ 95 (or later) or a Macintoshâ 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-waycable 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 EtherLinkâ III3C509B-TPONIC 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.



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 toSettings, and then clickControl Panel.

2.Double-clicktheNetwork 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 3C509BTPO 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


5.Click Protocol, and then clickAdd...

6.Click Microsoft in the “Manufacturers:” list and then clickTCP/IP in the “Network Protocols:” list. ClickOK.