Cainiao network transmission medium-twisted pair wires

With the extensive use of computers, network and Integrated Wiring have naturally become a hot topic. Correct design and layout of a network system not only improves the speed and reliability of communication, but also greatly improves the work efficiency; in cabling, the carrier for signal transmission-transmission media must be used. In a complete and stable network environment, the selection and correct utilization of transmission media are required, it is the basis for the long-term stability of the network. This article will lead you to understand the most common twisted pair wires used in the current networking process.

We often call twisted pair cables as network cables. In practice, there are two types of network cables: one is that the coaxial cable has basically been eliminated) and the other is the twisted pair cable. The twisted pair wires can be divided into shielded twisted pair wires and unshielded twisted pair wires, most local networks use Unshielded Twisted Pair wires (UTP-Unshielded Twisted Pair) as the transmission medium for cabling. A single network cable consists of a long Twisted Pair wires and RJ45 headers. Currently, cable twisted pair wires are sold on the market ". Most users purchase three types of cables and five types of cables. Currently, cat5e and cat5e unshielded twisted pair 1 are used. The transmission performance is 100 MHz and the transmission rate is 155 Mb/s. In addition, these twisted pair wires have the following features:

The diameter is small, saving the occupied space.
Light Weight, easy to bend, easy to install.
It is flame retardant, independent, and flexible.

Speaking of twisted pair wires, we must also talk about the production of crystal head and twisted pair wires. Because twisted pair wires are two NICs to connect to the computer, and there is no connection between the two ends of the twisted pair wires at the beginning of use, it is necessary to use the crystal head.

1. Crystal head

The crystal head is also known as RJ45 connector, as shown in figure 2. Although the head is small, the two ends of each twisted pair must be connected to the nic and hub by installing the crystal head.

When connecting, hold the crystal head in one hand, let the plastic shrapnel of the crystal Head Face itself or down, then you can see eight metal pins at the top of the twisted pair insertion port, from left to right, 1st feet, 2nd feet ...... 8th feet. When inserting twisted pair wires, make sure that they are in full contact with the pins to communicate properly.

Ii. Production of twisted pair wires

The most common network structure can be divided into dual-host direct connection and multi-host interconnection, while the production of twisted pair wires is also exquisite. Different network structures need to be connected using twisted pair wires of different practices. You can use these cables in accordance with the following principles: for network devices such as computers, you should use a direct connection line during connection and exchange, that is to say, the two ends of the twisted pair are arranged in the same order. The following rule is followed:

Orange white -- 1, orange -- 2, green white -- 3, blue -- 4, blue white -- 5, green -- 6, brown white -- 7, brown -- 8

When a common parallel interface is used for level-level connections between devices, such as between switches, cross-line connections are used. The arrangement rules of such twisted pair wires are as follows:

Green white -- 1, green -- 2, orange white -- 3, blue -- 4, blue white -- 5, orange -- 6, brown white -- 7, brown -- 8

After understanding the following principles, the next step is the specific production.

Step 1: Take the network cable 3-5 cm at one end, put it into the Pressure clamp circular knife interface, a little force pressed the handle so that the pressure clamp in the vertical direction of the network to rotate around 60 °, pay attention to be careful, do not twist the wire in it), so that the outer skin of the twisted pair can be cut without hurting the internal line, as shown in 3.

Step 2: A twisted pair is displayed, as shown in Step 4. There are four pairs in total. Split each pair of lines in sequence and flatten them to facilitate the re-arrangement of the backend.

Step 3: sort the line pairs in different order as described above and arrange them neatly. Then, cut them with a knife in front of the crimping tool.

Step 4: The crystal head has a plastic shrapnel side down, be careful to put all the lines into the pin 5 of the crystal head), and finally put the crystal head into the pressure wire mouth of the Pressure clamp, press the 6 handle of the Wire Clamp), and the installation is in place only when a slight sound is heard. Finally, use the wire tester to test whether the network cable is normal.

Iii. Testing of twisted pair wires

After the production of twisted pair wires, dedicated network cable tester 7 is usually used to determine the connectivity, and the single user can complete the process. It can detect 5E, 6E, STP/UDP twisted pair wires. Some products can also detect wiring faults of coaxial cables and telephone lines. The function is more powerful. It can test various situations such as open circuit, short circuit, cross connection, reverse connection and serial connection. It can locate connection and connection errors. It can also measure the line length and determine the distance between short-circuit and open-circuit connections.

When the network cable tester is used, insert the crystal head at both ends of the network cable into the RJ-45 port of the main tester and Remote Test end, switch to "ON" S for slow speed ), the host indicator lights are shining sequentially from 1 to G, indicating that the network connection is normal.

If several wires in the network cable are broken, the indicator light of the corresponding line number on the main test end and Remote Test end will not be on.

4. Twisted Pair wires and crystal heads

In addition to understanding the use environment and production methods of twisted pair wires, you should also learn more about the related knowledge. In this way, we can better use such transmission media. For example, the use length of twisted pair wires should not exceed 100 meters. Otherwise, the transmission of signals or the underlying connection may be affected.

1. How to Use twisted pair wires in a network environment over 100 meters.

As mentioned above, when the length of twisted pair wires exceeds 100 meters, the signal transmission will be affected. What should I do if it must be used in an environment larger than 100 meters? At present, the industry is more mature way is to add a device similar to the bridge to solve, such as CIP-SS-96 serial port + TCP/IP conversion server, 8 shown.

Figure 8

This is a device networking server that enables industrial RS-232/485/422 serial port Devices to instantly connect to the Internet, they do not need to run independently of the PC, support RS-232/485/422 communication interface. It is easy to set programs, port rates, and application modes.

The implementation principle is: the device that needs to be remotely connected is directly connected with the serial port of the CIP-SS-96 and the serial port of the TCP/IP conversion server, then the CIP-SS-96 serial port and TCP/IP conversion server will automatically package the signal generated by the device into an IP packet sent to the Ethernet, after the signal arrives at Ethernet and is processed, it is restored to the signal required by the device through CIP-SS-96 serial port and TCP/IP conversion server.

Tip: The network cable is cut off about 80 meters from the near end, and then connected together can also achieve remote connection within 200 meters.

2. Twisted Pair outer text.

Twisted Pair wires generally have a text every 2 feet, which explains information about the cable. For example, the text of a cable from the company "amp systems CABLEE138034 0100 24 AWG (UL) CMR/7D or c (UL) PCC FT4 verified etl CAT5 O44766 FT 9907 ", the specific meaning of which is described as follows:

AMP: name of the company.
0100: 100 ohm.
24: indicates that the core of the 24-digit series has three specifications: 22, 24, and 26 ).
AWG: Specifies the u. S. Cable specification standard.
UL: indicates the authentication criteria.
FT4: 4 pairs.
CAT5: CAT5.
044766: the current number of feet of the cable.
9907: indicates the production year and month.

3. Product related.

Because of its low price, high quality, and many other features, Category 5 is the preferred medium for Fast Ethernet (100 Mbps). Category 5 is mainly used in Gigabit Ethernet (1000 Mbps) and has evolved from Category 5. Category 6 products are the latest standard, which balances the data transmission throughput that previously could not be achieved by wiring products. Category 6 products are also compatible with Category 5 and Category 5 products. As for product brands, such as AMP, AVAYA, IBDN, panda, Simon, and nexson, they have a good reputation in the market. The price is mainly calculated in meters, and the general market price is 1-3 yuan/meter.

4. Select the crystal head correctly.

The crystal head may be nothing more common in cabling products. It seems that this is not important, but it has led to a lot of network failures, so the purchase is still a little bit exquisite. Pay attention to the following aspects in general:

1) good crystal headers have manufacturer labels on shrapnel and are crystal clear.
2) if you use your finger to pull the shrapnel with a good quality crystal head, you will hear the sound of zookeeper. If you move the shrapnel forward to 90 °, it will not be broken, and it will be restored and the elasticity will not change. In addition, when you insert a prepared crystal head into the NIC, you can hear the crisp sound.
3) fragment occurs when the crystal head with poor plasticity is squashed by the crimping tool.

V. network faults caused by twisted pair wires and troubleshooting

Network faults caused by broken outer skin of twisted pair wires and poor contact with the crystal head may occur from time to time. Here are several examples to help you learn from.

1. Solution to network cable breakage.

Phenomenon: Generally, all network cables and power cables are bundled together in the underground or wall. If it is determined that the network cable is damaged, so how can we find the broken points and determine which lines are broken?

Figure 9

Analysis and Solution: In addition to the common network cable tester, a device named straight-through network cable adapter 9 is also used to solve this problem ). This device can be used for network cable extension, and can also be used for network cable damage identification.

The implementation steps are as follows: Find a normal network cable adjacent to the faulty computer, insert it into the network adapter together with the faulty network cable, and connect the two ends of the two network cables to the network cable tester. Because one of the two network cables is normal, and the network adapter is straight-through, the network cable tester can immediately reflect the broken one.

2. Network Connection interruption caused by poor contact with the crystal head.

Phenomenon: when surfing the Internet, there is always a prompt that "the network cable is not ready" from time to time, but the network cable has not been moved.

Analysis and Solution: First, you need to check whether there is a problem with the network card. After the Network Card problem is eliminated, check carefully whether there is any damage to the network card. If the problem persists, it should be suspected that the contact between the crystal head and the network cable is poor. Find the network cable and the crystal head and re-create a new one, insert the original network card test, successfully solved the problem.

Problem reminder: The network cable is connected to the connector through eight contacts, and the connector is connected to the connector through the flexibility of the contact. If the network cable is frequently plugged and pulled for a long time, it will lead to reduced flexibility and poor contact. In addition, some poor crystal head touches are not elastic enough, this type of fault is more likely to occur.(