8P8C
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The 8 Position 8 Contact (8P8C, also backronymed as 8 position 8 conductor; it is often incorrectly called RJ45)[1] plugs and sockets are most regularly used as an Ethernet connector.[2] 8P8C connectors are typically used to terminate twisted pair cable.
8P8C has two paired components: the male plug and the female socket. Each has eight equally-spaced conducting channels. On the plug, these conductors are flat contacts positioned parallel with the connector body. Inside the socket, the conductors are suspended diagonally toward the insertion interface. When an 8P8C plug is mated with an 8P8C socket, the conductors meet and create an electrical connection. Spring tension in the socket's conductors ensure a good interface with the plug and allow for slight travel during insertion and removal. The 8P8C connector is probably best known for its use in Ethernet; since around 2000, it has been used almost universally as the connector on Ethernet network cables, and has replaced many older connector types such as BNC connectors. Older connectors have also been phased out as modern cables no longer have the high current and voltage requirements for which the bulkier connectors were designed.
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[edit] Standardization
The shape and dimensions of an 8P8C modular connector are specified for U.S. telephone applications by the Administrative Council for Terminal Attachment (ACTA) in national standard ANSI/TIA-968-A. This standard does not use the short term 8P8C and covers more than just 8P8C modular connectors, but the 8P8C modular connector type is the eight position connector type described therein, with eight conductors installed.
For data communication applications (LAN, structured cabling), International Standard IEC 60603 specifies in parts 7-1, 7-2, 7-4, 7-5, and 7-7 not only the same physical dimensions, but also high-frequency performance requirements for shielded and unshielded versions of this connector for frequencies up to 100, 250 and 600 MHz, respectively.
[edit] Wiring
It is frequently terminated using the T568A or T568B pin/pair assignments that are defined in TIA/EIA-568-B. A cable that is wired as T568A at one end and T568B at the other (Tx and Rx pairs reversed) is a "crossover" cable. Such a cable often has a red sheath and, before the widespread acceptance of auto-MDI/MDIX capabilities, was needed to interconnect similar network equipment (such as hubs to hubs). Crossover cables are still used today to connect two computers together without a switch or hub. A cable wired the same at both ends is called a "patch" or "straight-through" cable, because no pin/pair assignments are swapped.
[edit] Types
There are two types of 8P8C plugs, sockets, and diesets (used for crimping): Western Electric/Stewart Stamping (WE/SS) and Tyco/AMP. While both types look remarkably similar, they are mutually exclusive and cannot be interchanged. Tyco/AMP 8P8C plugs are proprietary, and have smaller spacing between contacts than the WE/SS style. As a result, using a WE/SS 8P8C crimp dieset on a Tyco/AMP 8P8C plug will crush the top of the connector, and vice versa. While the WE/SS 8P8C plug is more common than Tyco/AMP, it is still important to know what style is being used to avoid damaging the plug during crimping.
WE/SS 8P8C plugs come in shielded and unshielded varieties, depending on the attenuation tolerance needed. All Tyco/AMP 8P8C plugs include a metal ferrule, and so shielding comes standard. Shielded plugs are more expensive, but have a lower attenuation and can reduce signal noise. WE/SS plugs are available from a large number of manufacturers, whereas Tyco/AMP plugs are produced exclusively by Tyco Electronics.
[edit] Termination
Termination of a cable with an 8P8C plug involves using a hand crimper or crimp machine containing an 8P8C die-set or an A67T standard die-set. An 8P8C crimp die-set usually looks similar to an 8P8C socket, except for the eight teeth lining the top portion of the die. When the tool is operated, the die compresses around the 8P8C plug. As the die compresses, these teeth force the plug contacts down into the conductors of the cable being terminated, permanently attaching the plug to the cable. The crimper may also permanently deform part of the plug body in such a way that it grips the outer sheath of the cable. This helps to keep the plug securely fastened to the end of the cable.
[edit] Applications
8P8C are commonly used in computer networking, where the plug on each end is an 8P8C modular plug wired according to a TIA/EIA standard. These cables are typically used to connect Ethernet or Token Ring network interfaces. Most network communications today are carried over Category 5e or Category 6 cable with an 8P8C modular plug crimped on each end.
The 8P8C modular connector is also used for RS-232 serial interfaces according to the EIA/TIA-561 standard[1]. This application is commonly used as a console interface on network equipment such as switches and routers. Other applications include other networking services such as ISDN and T1.
In floodwired [3] environments the center (blue) pair is often used to carry telephony signals. Where so wired, the physical layout of the 8P8C modular jack allows for the insertion of an RJ11 plug in the center of the socket, provided the RJ11 plug is wired in true compliance with the U.S. telephony standards (RJ11) using the center pair. The formal approach to connect telephony equipment is the insertion of a type-approved converter.
The remaining (brown) pair is increasingly used for Power over Ethernet (PoE). Legacy equipment may use just this pair; this conflicts with other equipment as manufacturers used to short circuit unused pairs to reduce signal crosstalk. Some routers/bridges/switches can be powered by the unused 4 lines — blues (+) and browns (−) — to carry current to the unit. There is now a standardized scheme for Power over Ethernet.
Different manufacturers of 8P8C modular jacks arrange for the pins of the 8P8C modular connector socket to be linked to wire connectors (often IDC type terminals) that are in a different physical arrangement from that of other manufacturers: Thus, for example, if a technician is in the habit of connecting the white/orange wire to the "bottom right hand" IDC terminal, which links it to 8P8C modular connector pin 1, in jacks made by other manufacturers this terminal may instead connect to 8P8C modular connector pin 2 (or any other pin).
[edit] See also
- Networking
- While the true RJ45 uses a different 8P modular connector type, RJ48, RJ49, and RJ61 do indeed use 8P8C modular sockets and plugs.
- RJ11: Interface used in many countries for regular POTS (plain old telephone system)
- See Registered jack for other, similar looking jacks, with which the 8P8C modular connector is likely (and often) confused
[edit] Notes
- ^ RJ45 is technically incorrect because the RJ45 standard specifies the mechanical interface but a different wiring scheme than T568A/B, which is often used for Ethernet and telephones.
- ^ Under the same naming scheme, an 8P6C connector has eight positions, with six positions containing conductors, and a 6P6C connector has six positions, all containing conductors.
- ^ floodwire is a chiefly British term for installing communications cables in a massive fashion in anticipation of their eventual use.
[edit] References
- ANSI/TIA-968-A: Telephone terminal equipment – Technical requirements for connection of terminal equipment to the telephone network
- IEC 60603-7-1: Connectors for electronic equipment — Part 7-1: Detail specification for 8-way, shielded free and fixed connectors with common mating features, with assessed quality
- IEC 60603-7-2: Connectors for electronic equipment — Part 7-2: Detail specification for 8-way, unshielded, free and fixed connectors, for data transmissions with frequencies up to 100 MHz
- IEC 60603-7-4: Connectors for electronic equipment — Part 7-4: Detail specification for 8-way, unshielded, free and fixed connectors, for data transmissions with frequencies up to 250 MHz
- IEC 60603-7-5: Connectors for electronic equipment — Part 7-5: Detail specification for 8-way, shielded, free and fixed connectors, for data transmissions with frequencies up to 250 MHz
- IEC 60603-7-7: Connectors for electronic equipment — Part 7-7: Detail specification for 8-way, shielded, free and fixed connectors, for data transmissions with frequencies up to 600 MHz
- ISO/IEC 8877, EN 28877: Information Technology - Telecommunications and Information Exchange between Systems - Interface Connector and Contact Assignments for ISDN Basic Access Interface Located at Reference Points S and T
[edit] External links
- How to Make a Network Cable
- How to wire a 10BaseT or 100BaseT connector with Category 5 cable and 8P8C modular connectors
- Step by Step Instructions on How to Punch Down Category 5e Cable to a RJ45
- How to create your own Ethernet Cables
- TIA-968-A — Contains dimensions for sockets and plugs.
- Catalog page showing the difference between solid and stranded contacts
- Diagram of RJ45S showing the difference between an 8P8C and a true RJ45 8-position keyed connector.
- USOC RJ45S with programming resistor has a different shape than the computer "RJ45".
- RJ45 Pinouts and cables schematics (including network cables)
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