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RJ11, RJ45 Modular Connector Tutorial

by www.fiber-mart.com



Rj Connector Modular Connector Overview


Modular connector, also called modular phone jack/plug, RJ connector, and Western jack/plug, is the name given to a family of electrical connectors originally used in telephone wiring and now ommonly used for telephone systems, data networks, and low-speed serial connections. The most well known applications of modular connectors are for telephone jacks and for Ethernet jacks, both of which are nearly always modular connectors.  Modular connectors are inexpensive, relatively simple to terminate, and easy to plug and unplug. A modular connector typically has a clear, plastic body, with a tab that locks the plug and jack into place when connected.smc electric rj11 modular ends

Modular connectors have gender: male connectors are called plugs, while female connectors are called jacks or, sometimes, sockets. In the vernacular used by the technology industry, modular connectors are called RJ connectors. "RJ" is an acronym for Registered Jack, with the letters RJ to denote the capabilities of jacks in a building, and how they should be wired in order to connect to the public phone network. RJ plug connections are typically terminated by using a crimping tool to crimp the connector onto the conductors of a cable.

The modular connectors are designed with two numbers that represent the quantity of positions and contacts, with each number followed by a "P" and "C", for example, "6P2C" for a modular connector having 6 positions and 2 contacts. Alternate designations omit the "P" and "C" while separating the position and contact quantities with either an "x" ("6x2") or a slash ("6/2"). For instance, RJ11 connectors often with 6 positions and 4 contacts, to which are attached just 2 wires.


Position of RJ Modular Connectors


Modular connectors come in four sizes: 4-, 6-, 8-, and 10-position, where a position is a location for a contact. Not all of the positions may have contacts installed. Which means modular plugs are described as containing a number of potential contact "positions" and the actual number of contacts installed within these positions. When contacts are omitted, they are typically done so from the outermost pair of contacts inward, such that the number of contacts is almost always an even number. Following picture figures a 8P8C RJ45 connector.




The insulating plastic bodies of 4P and 6P connectors have different widths, whereas 8P or 10P connectors share an even larger body width. The connector body positions with omitted contacts or contacts unattached to wires are unused for the electrical connection, but ensure that the plug fits correctly.


4P and 6P RJ connector


Blades of Modular Connectors


Modular plugs come with either 2-prong or 3-prong blades. 3-prong blades are the best contact blades you can buy currently and generally found on high quality modular plugs. They hold the wire in the modular plug more efficiently than the 2-prong blades. 3-prongs are designed to be used with either stranded, solid or modular wires. On the contrary, 2-prong blades have different blades for solid, stranded and modular. For solid wire modular plugs, 2-prong blades have chiseled sides to the blades, where stranded wire modular plugs do not.

Blades Of Modular Connectors


Types of RJ Modular Connectors


The terms RJ-11, RJ-12, RJ-22, MMJ, RJ-45, and RJ-48 such are frequently used modular connectors. They are described in below table.


Common Types Detail Applications
RJ9 4P4C Typically used on telephone handsets.
RJ10 4P4C Typically used on telephone handsets.
RJ11 4P or 6P4C Mostly used for terminating telephone wire, for single line POTS telephone jacks in most homes.
RJ12 6P6C Used for voice/data applications: telephone (two-line), networking, extended-distance peripherals.
(Modified Modular Plug/Jack)
6P Similar to the regular RJ12 except with an offset latch. Found most often on older DEC products.
RJ14 6P4C Mostly used in analog (telephone) wiring.
RJ22 4P4C Used for coiled handset telephone cords.
RJ25 6P6C Mostly used in analog (telephone) wiring.
RJ45 8P8C or 10P10C Commonly used for Ethernet over twisted pair, registered jacks, LAN (10baseT and 100BaseT) and RS232 wiring and other telephone applications.
RJ48 8P8C A shielded version of the RJ-45 connector. Commonly used for T1 or other "leased-line" applications.
RJ50 10P10C Mostly used in proprietary data transfer systems,used to implement RS-485 interfaces, and for data link connections.

PC: RJ11, RJ14, and RJ25 all use the same six-position modular connector, thus are physically identical except for the different number of contacts (two, four and six respectively). RJ11 often actually use 6P4C RJ14 connectors (six position, four contacts), with four wires running to a central junction box.

The differences between RJ11, RJ12, RJ22, RJ45, and RJ48 may be confused. Through the table above, you can easily figure them out.

RJ11 and RJ12 bodies are exactly the same size bodies. The only difference is the number of contact blades. RJ11 has 4 and RJ12 has 6 contact blades. RJ11 can be substituted with RJ12 but not RJ12 for RJ11. RJ22 handset modular plugs are narrower than RJ11 and RJ12 bodies. RJ22 are used for coiled handset telephone cords. RJ45 and RJ48 bodies are exactly the same and are long bodies. RJ45 have 8 contact blades while RJ48 have 10.

Wiring of RJ Connectors

RJ connectors are frequently terminated using the T568A or T568B pin/pair assignment. A cable that is wired as T568A at one end and T568B at the other is a crossover cable. Crossover cables are used to connect two devices without a switch or a hub, typically used for direct computer-to-computer connections. A cable wired the same at both ends is called a “patch” or “straight-through” cable, which cables need a hub or switch to connect to. The T-568B wiring scheme is by far the most common, though many devices support the T-568A wiring scheme as well.


Wiring Of RJ Connectors


RJ45 Plug & Jack


Among the 4P4C, 6P4C, 6P6C, 8P8C, and 10P10C modular plugs, 8P8C connector is the most common used plug currently. The 8P8C connector or RJ45 connector (Electronics catalogs commonly advertise 8P8C modular connectors as "RJ45") are commonly used for Ethernet over twisted pair, registered jacks and other telephone applications, RS-232 serial using the EIA/TIA 561 and Yost standards, and other applications involving unshielded twisted pair, shielded twisted pair, and multiconductor flat cable. RJ45 connector selection includes standard RJ45 connectors, shielded RJ45 connectors, and IP67 waterproof RJ45 plug options for Cat 5, Cat5e, Cat6 and Cat7 applications.

Snagless boots to your cables before crimping the ends on. They are compliant with Category 5E, CAT6, Cat7, RJ45, 8P8C type cables. Color coding make it possible to tell the difference between Cat5e boots cables and Cat7 boots cables when nestled in the same patch panel or wall mount.




Snagless plugs are designed with features that significantly reduce the possibility of the retainer tab getting caught on something and breaking. The snagless plugs eliminate the need to replace broken plugs; this also results in less disruption to productivity for computer users. Plus, it brings field-terminated cables closer to the same performance standards as factory-terminated cables.


Fiber-Mart RJ Modular Plug Solution

Manufactured to meet or exceed UL 94V-0 and 1863 fiber rated standards Maximum number of connects and disconnects Bodies are made with crystal clear polycarbonate Modular plugs with the 3-prong blades Packaged in zip lock bags Available in RJ22, RJ11, RJ12, RJ45, and RJ48 configurations RJ-45 modular plugs available in Cat 5e, Cat 6, Cat7 and shielded configurations

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