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EtherExpress™ Adapter
10Base-T Cable and Pinout Information (Twisted Pair)

10BASE-T cable and pinout information

This document covers the following topics:

  • Recommended cables
  • Cable and connector pinouts
  • Connecting two computers without a hub
  • Link integrity
  • Common problems
For more information on the 10BASE-T specification, contact your local network supplier or call the IEEE (800-678-IEEE).

The EtherExpress™ adapters have a small, snap-in RJ45 connector.

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

Recommended Cables

The RJ45 connector can use 22, 24, or 26-gauge UTP cabling. The cable must comply with the IEE 802.3 10BASE-T standard.

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

These UTP cables work well:

ManufacturerModel numberNo. of pairs
Belden95622
Belden95666
Data Set24024

Silver satin is not within the 10BASE-T specification and cannot be used. If used, it may not work at all or may give intermittent results.

The EtherExpress adapters don't support pre10BASE-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.

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

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

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

Pinout for the RJ45 Connector

	   PINOUT FOR RJ45 CABLE CONNECTOR:
	   --------------------------------
	               ----------              --------------------------
	            1 |--        |          8 |------------              |
	            2 |--        |          7 |------------              |
	            3 |--         ---       6 |------------              |
	            4 |--            |      5 |------------              |
	            5 |--            |      4 |------------              |
	            6 |--         ---       3 |------------              |
	            7 |--        |          2 |------------              |
	            8 |--        |          1 |------------              |
	               ----------              --------------------------
	                  END                             TOP
	

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 connected

  5. not connected

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

  7. not connected

  8. not connected

Connecting Two Workstations Without a Hub

10BASE-T uses a star topology. This means there is a hub or concentrator in the center of a star and each workstation or server is connected to this hub.

For test purposes, you can directly connect two workstations or a workstation and a server without using a hub. This requires a special cable that incorporates the crossover function talked about at the beginning of this document.

	               Function    Pin#               Pin#   Function
	              --------------------------------------------------
	                 TX+        1    <-------->   3        RX+
	                 TX-        2    <-------->   6        RX-
	                 RX+        3    <-------->   1        TX+
	                 RX-        6    <-------->   2        TX-
	              --------------------------------------------------
	                              CROSSOVER CABLE
	
Note: This is not an IEEE supported configuration and should be used for test purposes only.

Link Integrity

For 10BASE-T networks, Link integrity (LI) needs to be on. Some transceivers, Ethernet cards, or other network devices allow you to turn Link Integrity off, but Link Integrity is always on with the EtherExpress cards.

If you're using a transceiver to go to a thick/thin ethernet segment, Link Integrity must be set to on for the transceiver.

Trouble Shooting Notes from Technical Support

A Hub Can't "See" a Workstation

A wire may be crossed in the cable or wiring closet. Check to make sure the wiring is correct.

Workstations Can't Connect to the Network

If your workstations are having problems connecting, reset or power off/on your concentrator or hub.

Polarity Problems

A common problem in 10BASE-T wiring is crossing the positive and negative phases of the transmit or receive signals. For example, a problem would occur if pins 1 and 2 were crossed. (TX+ connected to TX-).

The current EtherExpress adapters automatically detect a polarity problem and adjust for it internally. Early EtherExpress 16TP's didn't have this feature.

Even though the current EtherExpress adapters can take care of the crossover for you, it is best to check your wiring and correct polarity problems when you find them.

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