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RJ-45

The RJ-45 connector is commonly used for network cabling and for telephony applications.  It's also used for serial connections in special cases.  Here's a look at it:

RJ-45 Connector

Pinout for Ethernet

Although used for a variety of purposes, the RJ-45 connector is probably most commonly used for 10Base-T and 100Base-TX Ethernet connections.

Pin #

Ethernet 10BASE-T
100BASE-TX

EIA/TIA 568A

EIA/TIA 568B or AT&T 258A

1

Transmit +

White with green strip

White with orange stripe

2

Transmit -

Green with white stripe or solid green

Orange with white stripe or solid orange

3

Receive +

White with orange stripe

White with green stripe

4

N/A

Blue with white stripe or solid blue

Blue with white stripe or solid blue

5

N/A

White with blue stripe

White with blue stripe

6

Receive -

Orange with white stripe or solid orange

Green with white stripe or solid

7

N/A

White with brown strip or solid brown

White with brown strip or solid brown

8

N/A

Brown with white stripe or solid brown.

Brown with white stripe or solid brown.

Because only two pairs of wires in the eight-pin RJ-45 connector are used to carry Ethernet signals, and both 10BASE-T and 100BASE-TX use the same pins, a crossover cable made for one will also work with the other.

Also, please note that it is very important that a single pair be used for pins 3 and 6.  If one conductor from one pair is used for pin 3 and a conductor from another pair is used for pin 6, performance will degrade.  See the following figure.

To learn more about Ethernet, check out Charles Spurgeon's Ethernet Reference

RJ-45 Pinout for RocketPort

The following chart shows the pinout for RJ-45 connectors used on certain RocketPort serial interface cards (manufactured by Comtrol).

Pin Name/Description
1  Request To Send
2 Data Terminal Ready
3 Ground
4 Transmit Data
5 Receive Data
6 Data Carrier Detect
7 Data Set Ready
8 Clear To Send

 

    Pinouts for ISDN

Here's an ISDN BRI U port pinout for a Cisco 750 series router:

Pin Function
1  Not used
2  Not used
3  Not used
4  U interface network connection (tip)
5  U interface network connection (ring)
6  Not used
7  Power (pass-through to S connector)
8  Ground (pass-through to S connector) 

 

The following chart shows the pinout for RJ-45 connectors used on certain ISDN S/T interfaces.  For more info, see ANSI T1.605.

Pin Color Name/Description
1  White/Orange  N/A
2  Orange  N/A
3  White/Green  Receive+
4  Blue  Transmit +
5  White/Blue  Transmit -
6  Green  Receive -
7  White/Brown   -48VDC (optional)
8  Brown  -48VDC Return (optional)

 


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This site last updated 7/11/2008