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What do the twisted pair network cable crystal head 8-core wires mean?
When many friends connect the network cable, they usually don't know the eight copper conductors in the network cable. Which of them can guarantee the normal network transmission?
The first thing to know is the overall effect of the eight copper wires. The eight copper wires are used to reduce the mutual interference of electromagnetic signals. Each two wires are twisted together at a certain density.
In this way, the radio waves radiated from each other will cancel each other when transmitting electrical signals, effectively eliminating interference. The name twisted pair is also derived from this structure.
The earliest application of twisted-pair wire was used for the transmission of telephone signals, but it was gradually introduced into the transmission of digital signals. Now, the widely used types are super-five twisted-pair wires and category 6 twisted-pair wires. The maximum bandwidth can reach 1000Mbps. The only disadvantage of the twisted pair is that the transmission interval is short, which can only reach 100 meters.
Generally, five types of super five types of twisted pairs require four pairs of wires, that is, 8 core wires. Below 100M, generally use 1, 2, 3, 6, four lines.
Positive line (standard 568B): the line sequence at both ends is the same, the line sequence is: orange white, orange, green white, blue, blue white, green, brown white, brown.
Reverse line (568A): The line sequence of one end is a straight line, and the other end is: green-white, green, orange-white, blue, blue-white, orange, brown-white, brown.
The first monitoring button: There is no need to remember the 568A line sequence. One does not need this line sequence anymore. When another one is used, the 13 and 26 can be reversed on the basis of B.
Specifically why the 1236 four wires are used, it is necessary to understand what the role of each core is:
1 Output data (+)
2 Output data (-)
3 Enter the data (+)
4 Reserved for phone use
5 Reserved for phone use
6 Enter data (-)
7 Reserved for phone use
8 Reserved for phone use
It can be seen that although the twisted pair has 8 core wires, in the currently widely used 100M network, only 4 of them are actually used, namely the first, second, third, and sixth, they are respectively Play the role of receiving and signaling. 4, 5, 7, 8 are bidirectional lines, reserved for use.
However, under the network operation higher than 100M, usually eight cores will be used. For example, six types of super six types of network cables not only need to use 1 3 2 6, eight cores need to be used, otherwise network operation will be unstable.
After stripping the network cable, we can find that the density of the four pairs of twisted pairs is not the same. The two pairs of orange and green used to transmit data are significantly larger than the brown and blue pairs used for grounding and other public purposes. When you usually do jumpers, they are arranged strictly in the order of 568B.
I often hear people say, "I like to use the sorting sequence I am used to make lines, can it be used?"
In this way, you can use it casually at home, if you are still strict in the project and follow the line order. Otherwise, the effect of twisted pair is lost. Data transmission attenuation is severe, and the transmission distance is greatly reduced.
Here we want to emphasize that if you must arrange the wire sequence according to your own habit, you must put 1 3 two cores on a pair of twisted pairs and 2 6 two cores on a pair of twisted pairs.