What is Twisted Pair cable?
From the point of view of the standard Twisted Pair cable, there are 8 standard copper wires inside, and they are twisted into 4 pairs and arranged in a certain order. The standard Twisted Pair-wire has two wire sequences, namely T568A and T568A. T568B.
Although there are 8 copper wires inside the standard Twisted Pair-wire, only 4 are commonly used, of which 1 and 2 are used for data transmission, 3 and 6 are used for data reception, and 4, 5, 7, and 8 are bidirectional transmission lines. It is not used in Twisted Pair cable, but it is also used in some specific application environments. The function of each wire in the Twisted Pair cableis strictly regulated. In actual production, it must be connected according to a specific standard and a specific wire sequence to achieve data transmission.
In addition, the Twisted Pair cable has categories 3, 4, 5, super category 5 and even category 6. The rate of Category 3 Twisted Pair cable is 10Mb/S, the rate of Category 5 Twisted Pair wire can reach 100Mb/S, and the rate of Category 5e can reach more than 155Mb/s. Only Category 5 or Category 5e can be used for 100Base-TX .
Shielded Twisted Pair cable is more troublesome to manufacture because the outer layer of the cable is wrapped with aluminum to reduce radiation, and the price line is more expensive than unshielded twisted pair, so we commonly use it in 10Base-T or 100Base-TX networks. The ones are unshielded Category 5 and Category 5e Twisted Pair-wire.
How many types of Twisted Pair-wire?
There are two common classification methods of Twisted Pair-wire. One is to classify according to whether there is a shielding layer, which can be divided into shielded twisted pair STP (STP: Shielded Twist-ed Pair) and unshielded twisted pair UTP (UTP: Unshielded Twisted Pair);
The other is to classify according to the frequency and signal-to-noise ratio, which can be divided into: CAT1, CAT2, CAT3, CAT4, CAT5, CAT5e, CAT5, CAT6, CAT6A and CAT7.
Application of Twisted Pair cable
There are three connection methods of Twisted Pair cableaccording to different uses, namely Straight throug, ross over and Rolled connection.
The so-called Twisted Pair cable straight-through connection means that the Twisted Pair-wire is used to connect two different interfaces, such as a computer and a router/switch/hub, a router and a switch/hub, etc. It is the most common Twisted Pair-wireconnection. The same standard and the same line sequence are adopted, that is, both ends of the Twisted Pair-wire adopt the T568A standard, or all the T568B standard.
The Twisted Pair-wire cross connection refers to the Twisted Pair-wire used to connect two identical interfaces, such as data transmission between computers and computers, routers and routers, switches and switches, and hubs and hubs. It is also the most common Twisted Pair cableconnection. The two ends need to adopt different standards, that is, one end of the twisted pair adopts the T568A standard, and the other end of the Twisted Pair-wire adopts the T568B standard.
Twisted Pair cable all-reverse connection means that the twisted pair is not used for Ethernet data transmission connection. The same standard but different wire sequence is used, that is, the sequence of one end of the Twisted Pair-wire is 1-8 and the other end is the sequence of 8-1.
Take the currently widely used 100M network as an example: Ethernet 10/100Base-T interface: EIA/TIA T568B, its 1 and 2 copper wires are used for data transmission, 3 and 6 copper wires are used for data reception, 4, 5 , 7, 8 copper wires are not used.
How to make Twisted Pair-wire?
There are three common ways of using twisted pair according to different applications, but they all need to be standardized before being put into use. The corresponding production method mainly has three steps, namely production preparation, production process and function testing.
Before the standard wire is made, it must be fully prepared, which mainly involves Twisted Pair wires, tool pliers and crystal heads.
Among them, the twisted pair has specific quality standards according to specific application requirements, and needs to be selected according to the actual situation. The tool pliers are specially used for standard Twisted Pair wire cable production. From front to back, there are stripping openings, pressing grooves, and cutting openings, which have specific uses in the production process.
The crystal head is a standard device of twisted pair, and there is a corresponding metal sheet at each tooth connection inside, and the connection between the Twisted Pair wire and the crystal head is realized under the pressing of tool pliers.
Manufacturing process of twisted pair cable
Step 1: Cut the Twisted Pair wire of the specified length with the cutting edge of the tool pliers, and make appropriate reservations.
Step 2: Use the stripping port of tool pliers to strip the outer skin of the Twisted Pair wire, and straighten out the Twisted Pair wire.
Step 3: Sort according to the standard and cut the core wire flat with the cut off.
Step 4: Insert the crystal head in turn according to the standard wire sequence. Under the pressing of the pressing groove of the tool pliers, when a sound is heard, the crystal head of the Twisted Pair-wire has been made.
How to detect twisted pair?
The functional integrity of the finished standard cable needs to be checked and confirmed before it can be put into normal use. Usually, network engineers will also carry network cable testers when they go out for inspection.
The network cable tester is an instrument to test whether the connection method of the crystal head connected on both sides of the network cable is correct.
The network cable tester has two ports, one is the main test port and the other is the remote test port.
When using, connect one end of the network cable to be tested to the main test port and the other end to the remote test port, and then observe the light status of the 1-8 indicators on the main test port and whether the order of the lights is correct and reasonable.
The commonly used network cable tester can check all the core wires in the twisted pair one by one (pair), and can judge which one (right) is wrong, short circuit or open circuit.
However, the test cannot be carried out when the copper piece of the crystal head is not completely pressed down, otherwise the port of the network cable tester will be permanently damaged. damage.
The basic principle of the test is that when the two ends of the network cable tester are connected to Twisted Pair cables, the 8 core wires will be connected to the I/O of the microprocessor P0 port in the network cable tester in the order of the crystal heads, and the other One end is connected with the I/O of the microprocessor P2.
At this time, the microprocessor P0 port will automatically send a group of data, and transmit it to the microprocessor P2 port through the internal network. When the data received by the microprocessor P2 is consistent with the sent data, it means that the standard Twisted Pair cable core wire is connected correctly. .
The data is processed by the microprocessor P2, and the correct status is displayed through the external indicator light. On the contrary, if it is not correct, the microprocessor P2 will also indicate the corresponding incorrect line sequence, which gives the function detection of the actual standard Twisted Pair cable. It brings great convenience to work.
Step 1: Connect one end of the standard line to the main tester port, and the other end to the remote tester port, and turn on the tester. At this time, the indicator lights of the two testers flash in a certain order.
Step 2: Combine different connection methods to judge whether the standard line is correct or not through different phenomena.
For example: (1) When testing the function of the straight-through cable, if the connecting function of the straight-through cable is complete, the indicator lights of the main tester and the remote tester are flashing in the order from 1 to 8, otherwise, the connectivity is question.
(2) When testing the function of the crossover cable, if the connection function of the crossover cable is complete, the indicator lights of the main tester and the remote tester are respectively from 1 to 8 and according to 3, 6, 1, 4, 5, 2 , 7, and 8 flash in the order, otherwise, there is a problem with the connectivity.
For example, if the 1 light on the main test end is on, then the 1 light on the remote test end should also be on, and the 2 light on the remote test end is on, which means that there is a problem with the network cable connection and cannot be used normally. Among the 8 lights, if the 1, 2, 3, and 6 lights are on, the network cable can be used, because the data is transmitted through these 4 wires, and the remaining 4 wires are not used to transmit data.