100 Mbps cabling specifications
                                                                    v1.01


Specifications and recommendations for Twisted-Pair Ethernet
============================================================

EtherExpress(TM) PRO/100 Smart adapters have a small, snap-in RJ45
connector.

RJ45 cabling is also known as Twisted-pair Ethernet (TPE) or Unshielded
twisted pair (UTP), and 10BASE-T.

This document covers the following topics:

-  Recommended cables
-  Cable and connector pinouts
-  Link integrity
-  Common problems

For more information on the 100BASE-TX specification, ISO/IEC 8802-3,
contact your local network supplier or call the IEEE (800-678-IEEE).


Recommended cables
==================

The cable must comply with the IEEE 802.3 10BASE-T standard for 2-pair,
Category 5, UTP cable.

The cable between the computer and the hub must be less than 100 meters
long.

These UTP cables work well:

------------------------------------------------------
Manufacturer       Model number         No. of pairs
------------------------------------------------------
Belden             1588A                     2
------------------------------------------------------

EtherExpress PRO/100 Smart adapters do not support pre-10BASE-T
concentrators.


Cable and connector pinouts
===========================

If you need to repair a cable or provide connectors for UTP cable, wire
straight through as shown in the following table.

Function   Pin#              Pin#
-------------------------------------
TX+        1    <-------->   1
TX-        2    <-------->   2
RX+        3    <-------->   3
RX-        6    <-------->   6
-------------------------------------

Use only four of the eight pins. Pins 1 and 2 must be a pair, and pins 3
and 6 must be a pair.

To allow for a straight-through cable, the hub provides an internal
transmit/receive crossover function. This means the transmit circuit of
the network card is connected to the receive circuit of the hub and vice
versa.

Pinout for the RJ45 connector
-----------------------------
   ----------              -------------------------
1 |--        |          8 |------------             |
2 |--        |          7 |------------             |
3 |--         ---       6 |------------             |
4 |--            |      5 |------------             |
5 |--            |      4 |------------             |
6 |--         ---       3 |------------             |
7 |--        |          2 |------------             |
8 |--        |          1 |------------             |
   ----------              -------------------------
      END VIEW                        TOP VIEW

Pin name and function:

1  Transmit Data Plus. The positive signal for the TD differential pair.
   This signal contains the serial output data stream transmitted onto
   the network.

2  Transmit Data Minus. The negative signal for the TD differential pair.
   This contains the same output as pin 1.

3  Receive Data Plus. The positive signal for the RD differential pair.
   This signal contains the serial input data stream received from the
   network.

4  not used

5  not used

6  Receive data minus. The negative signal for the RD differential pair.
   This signal contains the same input as pin 3.

7  not used

8  not used


Link integrity
==============

There are two sets of LEDs on the EtherExpress PRO/100 Smart adapter: a
yellow set for 10 Mbps operation and a green set for 100 Mbps operation.
The LEDs are labeled LNK for link and ACT for activity.

The 10 MB LNK LED indicates that a link pulse is present on the cable.
The 100 MB LNK LED indicates that a link-idle pattern is present on the
cable.

The ACT LED indicates that there is read/write activity on the network.
It doesn't always mean there is activity on the adapter.


Troubleshooting
===============


Polarity problems
-----------------

A common wiring problem is crossing the positive and negative phases of
the transmit or receive signals -- for example, crossing pins 1 (TX+) and
2 (TX-).

EtherExpress PRO/100 Smart adapters automatically detect this problem and
adjust for it internally.

Even though the current EtherExpress PRO/100 Smart adapters can take care
of this crossover for you, it's best to check your wiring and correct
this problem if you find it.