What is the RJ45 Jack
Aug 05, 2023
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The RJ45 jack is a type of connector in the cabling system, consisting of plugs and sockets. These two components of the connector are connected to the wires to achieve electrical continuity. The RJ45 jack is the most important type of socket in the connector.
1. What is RJ?
RJ stands for Registered Jack, which means "registered socket." In the FCC (Federal Communications Commission Standards and Regulations), RJ is used to describe interfaces of public telecommunications networks. Common ones include RJ-11 and RJ-45, with RJ-45 being the colloquial term for the standard 8-position modular interface used in computer networks. In previous Category 4, Category 5e, Category 6, and recently introduced Category 6 cabling, the RJ type interface was used. In Category 7 cabling systems, "non-RJ type" interfaces are allowed. For example, on July 30, 2002, Siemon's Category 7 connectors were officially selected as the standard mode for non-RJ type Category 7 industrial interfaces. The TERA connector has a transmission bandwidth of up to 1.2GHz, exceeding the currently developing 600MHz Category 7 standard transmission bandwidth.
2. Four Types of RJ modules
There are four basic types of RJ module sockets commonly seen in the field of network communication. Each basic socket can connect different configurations of RJ. For example, a 6-core socket can connect RJ11 (1 pair), RJ14 (2 pairs), or RJ25C (3 pairs); an 8-core socket can connect RJ61C (4 pairs) and RJ48C. An 8-core (Keyed) socket can connect RJ45S, RJ46S, and RJ47S. RJ45 sockets and RJ45 connectors are the basic connectors in comprehensive cabling systems. We will further discuss RJ45 connectors later.
3. What is RJ45 Jack
The core of the RJ45 jack is the modular socket. Gold-plated wires or socket holes can maintain stable and reliable electrical connections with modular plug contacts. Due to the friction between the contacts and the socket holes, electrical contact is further enhanced when the plug is inserted. The design of the socket body uses an integral locking mechanism so that when the modular plug (such as an RJ45 plug) is inserted, the interface between the plug and the socket can generate the maximum pull-out strength. The wiring block on the RJ45 jack connects the twisted pair through the wire groove, and the locking contacts can fix the RJ45 jack on information outlet devices such as panels. Figures 2-20 show the front view, side view, and three-dimensional view of the RJ45 jack, respectively.
Figures 2-22
4. The common types of RJ45 Jacks
Common unshielded rj45 modules are 2cm high, 2cm wide, and 3cm thick. The plastic body is resistant to high voltage and flame-retardant, with a UL 94V-0 heat rating. They can be inserted into any M-series modular panels, brackets, or surface-mount boxes, and can be installed on standard panels at a 90-degree (vertical) or 45-degree diagonal angle. The special design provides at least 750 repeated insertions and withdrawals. The rj45 module uses both T568A and T568B wiring labels and comes with a white flat cable insertion cover. This type of rj45 module typically requires a punch-down tool with a 110-type blade for cable termination. This unshielded rj45 module is also one of the most commonly used rj45 modules in domestic comprehensive cabling systems, maintaining a consistent appearance across Category 3, Category 5, Category 5e, and Category 6.
For user-friendly plug-and-play installation, users have also begun to prefer 45-degree diagonal operations. To achieve this, the current standard rj45 modules can be combined with panels angled at 45 degrees or the rj45 module mounting end can be directly designed at a 45-degree angle (Figure 2-21).
The design of no-punch-down tools also reflects the user-centric design of the rj45 module. Rj45 modules with no-punch-down tool design, such as the Siemon MX-c5 rj45 module with the no-punch-down tool design (left in Figure 2-22) and the Nexans LANmark-6 Snap-in rj45 module (right in Figure 2-22), do not require specialized tools for termination.
5. What is the ACO communication socket system
The ACO communication socket system (Figure 2-23) is a communication socket system launched by AMP. It uses a unique design and features a space similar in size to RJ45 standard rj45 modules for termination. This socket system consists of various communication interfaces and plug blocks, supporting not only voice and data application rj45 modules but also coaxial interfaces and audio-video interfaces. The rj45 modules are integrated with the panel, composed of surface-mount interfaces, connecting connectors, mounting bases, and covers (Figure 2-24).
In some new designs, multimedia rj45 jack interfaces appear to be not significantly different from standard data/voice rj45 jack interfaces. The benefit of this trend toward standardized modular design is that all rj45 jacks use the same size of space and installation accessories (Figure 2-25). Currently, both internationally and domestically, there is a trend toward the integration of VDV (Voice-Data-Video) applications. The new design rj45 Jack has made significant efforts in terms of user-friendly aspects.
6. The Termination Process of RJ45 Jack
The below diagram provides a detailed description of the termination process of the COBTEL Cat6 cable series on the MPS100E module.
7. The application of RJ45 Jack
In structured cabling, keystone modules are used to terminate cables and establish effective connections with patch cords. In some manufacturers' products, keystone modules are configured more scientifically with patch panels. These patch panels consist of an assembled empty plate and keystone modules of various types, allowing users to install corresponding keystone modules based on the actual application's keystone module type and quantity. In this case, the keystone modules also become a component of the patch panel (Figure 2-27 omitted). From here, we can summarize the application scenarios of keystone modules: terminated to different panels, installed in surface-mount boxes and other components, and installed in modular patch panels (Figure 2-28 omitted).
It should be noted that, due to the presence of a cross or isolation tape in the center of Category 6 cables, they should be cut off before termination.
9. The shielded and unshielded rj45 jacks
Keystone modules are also divided into unshielded keystone modules and shielded keystone modules. Figure 2-29 is a typical physical diagram of a shielded keystone module, and Figure 2-30 shows its structural diagram.
Figure 2-29 Shielded Keystone module Structural Diagram Figure 2-30 Shielded Keystone module Structural Diagram
9. The COBTEL built-in dust cover keystone module
Different manufacturers' keystone modules have unique designs. One of the most representative examples is the COBTEL built-in dust cover keystone module. The built-in dust cover socket series features a spring-loaded built-in dust cover that automatically retracts and pops out when inserting and removing patch plugs. Additionally, its unique spring-supported "gate" ensures that the patch plug will not be partially inserted, affecting stable data transmission. Traditional sockets with dust covers usually require the use of both hands to open the dust cover and insert the patch cord. However, Molex's enterprise cabling network department's built-in dust cover socket allows one-handed insertion of the patch cord, making it more convenient to use. Furthermore, the "gate" wipes the pins clean every time a connection/disconnection is made, comprehensively preventing dust and impurities from entering the connector, and ensuring maximum protection and reliable signal transmission capability. Molex's built-in dust cover socket has a compact appearance (21mm high × 21mm wide × 26mm thick) and achieves maximum density on each workstation. In a standard-size rectangular wall panel, up to 6 sockets can be accommodated; in a standard-size square wall panel with a dust cover, up to 4 sockets can be accommodated. Its density is equivalent to twice that of traditional sockets.
A type of shielded keystone module designed for industrial environment applications uses a different shielding method, with the outer ring surrounded and fastened by a screw structure
10. How to eliminate the crosstalk when Connecting the RJ45 Jack to modular plugs
When keystone modules are connected to modular plugs (RJ45 plugs), crosstalk is an important factor considered during design. To enhance the overall transmission performance of the link, crosstalk cancellation technology is often employed in sockets. Crosstalk cancellation technology works by generating an anti-phase crosstalk signal with the same magnitude as the interference introduced from the plug to cancel out the crosstalk.
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