RJ45 Cable

What does RJ45 mean?

RJ45 is short for registered jack. This abbreviation has become a commonly used term to describe a widely used plug in connection. This plug in connection was developed by Bell Laboratories in the USA. In the 70s they paved the way for switching telephone connections with screw in connections to connections with easy plug in connections which could be handled by everybody and not only qualified personnel. During this process RJ11, RJ14 and RJ25 plug in connectors were developed. Today these connectors are widely spread in the telephone sector (e.g. for connection of handset and basic device). RJ45 is mainly used in high speed networks (Ethernet, Industrial Ethernet).

For a more detailed specification the plug/socket description is being used. This details the number of positions and number of used contacts. The description 8P8C equals a plug with 8 pins and 8 cables. Configurations using less contacts than positions are common. One example is 6P4C for a RJ14 plug connector.

RJ45 - Difference between Standard and Every Day Language

To correctly understand the term RJ45 a differentiation in between the standard and every day language has to be made. Actually standardized is only the plug connector RJ45S. S means single cable. It is an 8P8C plug with key which means it has another edge on the housing which produces a very recognizable plug face. This plug face makes it impossible to combine the RJ45S with another 8P8C plug connector. Ahead of introduction of high speed internet connections at home RJ45S was developed for modem and data connections. As a result of this application the (technically incorrect) every day language term RJ45 for Ethernet connections based on 8P8C plug connections without key has become commonly used.

Standards for RJ45 Assignment

Standards have been developed for the RJ45 assignment. TIA-568A (EIA/TIA-568A) and TIA-568B (EIA/TIA-568B) are widespread. The abbreviation TIA is deviated from Telecommunications Industry Association which was involved in the development of these standards. Telecommunications Industry Association is a global joint venture of more than 400 institutes and companies. TIA-568A and TIA-568B are used for RJ45 assignment in Ethernet networks and telecommunication systems.

The RJ45 cable is set for both standards and ordered by colour. The difference is in switching the core pairs 2 and 3. To bridge the difference of RJ45 cables patch cables are available. RJ45 cables have 8 cores. They are grouped into 4 pairs. The pairs are twisted to reduce crosstalk. RJ45 cables and plugs are also available as a shielded version.

What is an RJ45 Connection?

An RJ45 connection is a connection based of standardized plug connections. Many devices in industrial electronics and other parts of electronics have one or more RJ45 connections and are therefore on the hardware side of things compatible to established communication standards like Industrial Ethernet with EtherCAT^(R), PROFINET and more.

An RJ45 connection can be protected for industrial environmental circumstances. Wall boxes according to IP65 standard for a RJ45 connection are available. In a data plug inlay an RJ45 connection can be mounted in combination with other types of connectors. This creates overview as well as the ability to expand data plug connections. When selecting an RJ45 connection it has to be taken into account whether the cable is shielded.