The signal definition of RJ45 connector and the arrangement order of RJ45 crystal heads are discussed in detail

1、 RJ45 connector

Just like the connector of the network plug on the back of the computer, the computer is inserted into the socket through the crystal head at the end of the network cable, so that the computer can connect to the network. RJ45 connector is composed of plug and socket as a whole, which is connected between wires to realize the electrical continuity of wires.

2、 RJ45 connector modular

Its core is modular socket. The gold-plated wire or socket hole can maintain a stable and reliable electrical connection with the modular socket spring. Due to the friction between the shrapnel and the socket, the plug is inserted and the electrical contact is further strengthened. The overall external design adopts the overall locking mechanism, which is pulled out by pressing the locking spring on the crystal head.

3. RJ45 crystal plug

Also called RJ45 plug.

It is used for the termination of data cables to realize the connection and change of equipment and distribution frame modules.

RJ45 crystal head needs good conductivity; The gold plating thickness of the contact is 50 μ m. Comply with more than 5 transmission standards and t568a and t568b line sequence; It has the functions of preventing loosening, plugging, self-locking, etc.

RJ45 plug is a standard connector in copper cable wiring. It forms a complete connector unit together with socket (RJ45 module).

The connector composed of these two parts is connected between the wires to realize the electrical continuity of the wires. It is also an integral part of the finished jumper of generic cabling technology. RJ45 crystal head is usually connected to both ends of stranded cable. In the standardized generic cabling design and installation, the accessory products are generally not listed separately, that is, users are not encouraged to complete the connection of twisted pair and RJ45 plug by themselves.

The information module or RJ45 connecting plug and the twisted pair end are connected with t568a or t568b structures.

In t568a, the 8 connected lines are respectively defined as: white green and green; White, orange and blue; White, blue, orange; White brown and brown.

In t568b, the 8 connected lines are defined as white orange and orange respectively; White, green and blue; White, blue and green; White brown and brown. Differential transmission lines are defined as white orange and orange cables, white green and green cables, white blue and blue cables, white brown and brown cables, respectively.

For best compatibility, the t568b standard is often used to make through lines. The sequence number of RJ45 crystal head pin shall be observed according to the following method:

Face the front of the RJ45 plug (one side of the copper pin) towards yourself, one end of the copper pin faces upward, and one end of the connecting cable faces downward. The eight copper pins are numbered 1 ~ 8 from left to right.

The corresponding sequence from lead 1 to lead 8 is as follows,

T568a: ① white green, ② green, ③ white orange, ④ blue, ⑤ white blue, ⑥ orange, ⑦ white brown, ⑧ brown.

Formula 1: green, blue, orange and brown, light color in the front, three to five exchange.

Formula 2: white green green, white orange blue, white blue orange, white tan.

T568b: ① white orange, ② orange, ③ white green, ④ blue, ⑤ white blue, ⑥ green, ⑦ white brown, ⑧ brown.

Formula 1: orange, blue, green and brown, light color in the front, three or five interchanges.

Formula 2: white orange, white green blue, white blue green, white brown brown.

There is no essential difference between the two types of international standards, only the difference of color. It is worth noting that when connecting two RJ45 crystal heads, it must be ensured that pins 1 and 2 are windings, pins 3 and 6 are windings, pins 4 and 5 are windings, and pins 7 and 8 are windings. In the same generic cabling system project, only one connection standard can be adopted. Generally speaking, TIA / eia-568-b standard is used to make connecting wires, sockets, distribution frames, etc., Otherwise, it should be clearly marked.

The performance indexes of RJ45 include attenuation, near end crosstalk, insertion loss, echo loss and far end crosstalk.

Performance technical description of RJ45: when the contact resistance is 2.5m Ω, the insulation resistance is 1000m Ω, and the electrical strength is DC1000V (ac700v), there is no breakdown and arcing within one minute. It is stuck on the surface and plated with gold or silver. The wiring diameter is 0.4mm ~ 0.6mm. The plug and socket can be plugged and unplugged 750 times, and the 8-wire contact pin is plated with gold 509 (inch).

RJ45 connector In some performance indexes of, some problems need to be considered by designers. In order to achieve better and smoother transmission performance, crosstalk cancellation technology is often used in sockets. Crosstalk cancellation technology can generate crosstalk signals with the same size and opposite polarity as the interference introduced from the plug to cancel crosstalk. If the crosstalk interference introduced by the modular plug is represented by + + +, the opposite crosstalk generated by the socket is represented by -. When the two crosstalk signals are equal and the polarity is opposite, the total coupled crosstalk interference signal is zero.