What is a structured wiring system

This paper systematically expounds the basic concept and development course of the structured wiring system, and also introduces the test of the structured wiring system.
A brief introduction of structured wiring system
With the rapid development of computer and communication technology, network applications become a growing demand, structured wiring is the foundation of network implementation, it can support data, voice and graphics and other transmission requirements, become the current and future computer network and communication system of strong support environment.
The structural wiring system is closely related to the development of intelligent building, and it is the foundation of Intelligent building. Intelligent building with comfort, security, convenience, economy and advanced characteristics, generally include: Central computer control system, building automation system, office automation system, communication automation system, fire automation system, security automation system, structural wiring system, etc., it through the building of four basic elements (structure , systems, services and management, and their intrinsically interconnected design, provide an environment with a reasonable investment and a high efficiency of elegance, comfort, convenience and safety. The structured cabling system is the basis for achieving this goal. ---http://bianceng.cn (computer science)
Second, the development of structured wiring
The initial implementation of structured wiring, has been in the teenage years.
1984, the world's first intelligent building produced. People of the United States in the city of Hart Ford is a building to transform the air-conditioning, elevators, lighting, fire anti-theft system, such as the use of computer monitoring, to provide customers with voice communication, word processing, electronic parts and information services such as intelligence. At the same time, a number of companies into the wiring field, but the product compatibility between manufacturers is poor.
At the beginning of 1985, the Computer Industry Association (CCIA) proposed the standardization of building wiring systems, and the American Electronics Association (EIA) and the American Telecommunication Industry Association (TIA) began standardization work.
July 1991, ansi/eia/tia568, "commercial building telecommunications wiring standards" came out, at the same time, and cabling channels and space, management, cable performance and connectivity hardware performance related to the relevant standards are also introduced.
At the end of 1995, the Eia/tia 568 standard was officially updated to Eia/ti A/568A, and the International Organization for Standardization (ISO) standard was iso/iec/is11801 for the corresponding standard.
The development of EIA/TIA568A standards is based on the following objectives:
* Establish a generic telecommunications cabling system that supports multi-vendor environments;
* The design and installation of a structured wiring system for commercial buildings;
* Establish and configure performance and technical standards for cabling systems.
The standard basically includes the following elements:
* The minimum requirements of telecommunication wiring in office environment;
* Proposed topological structure and distance;
* Determine the performance of the media parameters;
* Connector and PIN function distribution to ensure interoperability;
* Telecommunications cabling system requires more than 10 years of service life.
Third, the concept of structured wiring
1. Define
Structured wiring system is a telecommunication wiring system which can support any user's choice of voice, data and graphic image applications. System should be able to support voice, graphics, image, data multimedia, security monitoring, sensing and other transmission of information, support UTP, fiber, STP, coaxial cable and other transport carriers, supporting the application of multiple users of multiple types of products, support high-speed network applications.
2. Features
Structured wiring system has the following characteristics:
1 practicality: can support a variety of data communication, multimedia technology and information management system, can adapt to the development of modern and future technology;
2 Flexibility: Arbitrary information points can connect different types of equipment, such as computers, printers, terminals, servers, monitors and so on;
3 Open: able to support any manufacturer of any network products, support arbitrary network structure, such as bus-shaped, star-shaped, ring-type, etc.
4 Modular: All the connectors are block-type standard parts, easy to use, management and expansion;
5 Extensibility: After the implementation of the structured wiring system can be expanded, so that in the future when there is greater demand, it is easy to install equipment access;
6 Economy: One-time investment, long-term benefits, low maintenance costs, so that the overall investment to achieve the least.
3. Wiring system's composition
According to the general division, the structured wiring system consists of six subsystems: The working area subsystem, the horizontal branch backbone subsystem, the management subsystem, the vertical backbone subsystem, the equipment subsystem and the complex backbone subsystem.
1. Complex backbone Subsystem
Provide connection points between external buildings and the wiring within the building. The eia/tia569 standard stipulates the physical specification of the network interface and realizes the connection between the buildings.
2) Equipment Subsystem
The eia/tia569 standard stipulates the wiring of equipment between devices. It is the most important management area of the wiring system, and all floors are transmitted by cable or fiber optic cable. Typically, this system is installed in the mainframe room of computer systems, network systems, and program-controlled system computers.
3) Vertical Backbone subsystem
It connects communication rooms, equipment, and access equipment, including trunk cables, intermediate switches and main handover, mechanical terminals and connectors or plugs for trunk to trunk exchanges. The backbone wiring should adopt the star topology structure, the grounding should conform to the eia/tia607 requirement.
4) Management Subsystem
This section places the telecommunications wiring system equipment, including the horizontal and backbone wiring system of the mechanical terminals and 1 or exchange.
5) Horizontal Branch trunk Subsystem
Connect the management subsystem to the work area, including horizontal wiring, information outlets, cable terminals, and switching. The specified topological structure is a star topology.
Horizontal cabling can be selected with three kinds of media (100 ohms UTP cable, 150 ohm STP cable and 62.5/125 micron Optical cable), the farthest extension distance of 90 meters, in addition to 90 meters horizontal cable, the work area and management subsystem of the connector line and the total length of the cross wiring cable can reach 10 meters.
6) Workspace Subsystem
The workspace extends from an information outlet to a station device. The workspace cabling requirements are relatively simple, which makes it easy to move, add, and change devices.
4. Performance specification of media and connection hardware
In the structured wiring system, the wiring hardware mainly includes: wiring frame, transmission medium, communication socket, socket board, wire slot and pipeline, etc.
1) Media
Mainly twisted-pair and optical fiber, in our country mainly using unshielded twisted-pair cable and cable mixed use method. Optical fiber is mainly used for high quality information transmission and trunk connection, according to the signal transmission mode can be divided into multimode fiber and single-mode fiber two, the wire diameter of 62.5/125 microns. Multimode fiber is mainly used in horizontal connection, and single mode fiber is mainly used in vertical trunk. Now, the use of 100 ohm unshielded twisted pair has become a consensus, it is divided into 3 categories, 4 categories and 5 categories three.
2) Connectors and sockets
There should be at least two information outlets in each workspace, one for speech and one for data. Socket PIN combination: 1&2, 3&6, 4&5, 7&8.
3 The selection of shielding system
Our country basically uses the North American structural wiring strategy, namely uses the unshielded twisted pair 10 fiber the mixed wiring way.
(1) The meaning of shielding
The shielding system is to ensure the transmission performance of the system under the interference environment. Anti-jamming performance includes two aspects, that is, the system's ability to withstand external electromagnetic interference and the system itself to plug the electromagnetic interference capability, for the latter, Europe passed the EMC standard electromagnetic compatibility test. The general way to achieve shielding is to attach a metal shield on the outer layer of the hardware to remove unnecessary electromagnetic waves. Now has STP and SCTP two different structure of shielding line to choose.
(2) Defect of shielding system
A. Grounding problems
The shielding layer of the shielding system should be grounded. When the frequency is less than 1MHz, a little grounding can be. When the frequency is above 1MHz, EMC believes it is best to ground in multiple locations. The usual practice is to ground at the length of each wavelength one-tenth, and the length of the grounding wire should be less than one-twelveth of the wavelength. If the grounding is bad (the grounding resistance is too large, the ground potential is not balanced, etc.), it will produce a difference, which will constitute the biggest obstacle and hidden trouble to ensure the shielding system performance.
B. Integrity of the system
A shielded cable does not determine the overall EMC performance of the system. The integrity of the shielding system depends on the weakest Genreber in the system. such as the Jump Panel, connector information port, equipment and so on. Therefore, if the shielding line in the installation process of the attack seam, it constitutes the most dangerous part of the child shielding system.
C. Anti-jamming performance of screen stream
Shielding system can not lower the shielding layer low frequency noise, at low frequencies, shielding system noise at least the same as the non-shielding system.
Moreover, because the shielding 8-core Module plug no uniform standards, no on-site test shielding effective procedures, and other reasons, people generally do not use shielded twisted-pair cable.
IV. Wiring Test
The installation of the LAN starts from the cable, the cable is the foundation of the whole network system. The test of structured wiring system is essentially the test of cable. According to statistics, about half of the network failures and cable-related, the quality of the cable itself and the quality of the cable installation directly affect the network can run healthily. Moreover, the cable one and finished construction, want to maintain very difficult.
Now, the general use of 5 types of unshielded twisted-pair cable to complete the structured wiring. Most of the user's current application environment is embodied in the 10M network, so it is necessary to test the performance of the structured cabling system to ensure future application.
For the cable testing, generally follow the "with the installation with the test" principle. According to the definition of TSB67, field tests typically include wiring diagrams, link lengths, attenuation and near-end Crosstalk (NEXT).
1. Wiring diagram
This test verifies that the link is properly connected. Not only is it a simple logical connection test, but it is also necessary to verify that each stitch at one end of the link is connected to the corresponding pin on the other end, and to test the string around the problem and correct it in a timely manner. The guarantee line is a very important test item for correct stranding.
2. Link length
According to the t1a/e1a606 standard, each link length should be recorded in the management system. The length of the link can be estimated by electronic length measurement, which is based on the transmission delay of the link and the NVP value of the cable. Because the NVP has 10% error, the stability factor should be considered in the measurement.
3. Attenuation
Attenuation is the measurement of signal loss along the link. Attenuation varies with frequency, so the attenuation on all frequencies in the application range should be measured, and the maximum step size is 1MHz.
The TSB-67 defines a link attenuation formula and gives two attenuation allowable tables for the measurement modes. It defines the allowable value at 20 ℃.
4. Near-end crosstalk (NEXT) loss
Next loss is the measurement of the coupling of signals from one pair of lines to another in a link, that is, when the signal is running on a pair of lines, and a small number of signals are sensed to other line pairs, a phenomenon that is crosstalk.
The TSB-67 standard stipulates that 5 types of links must be tested in the bandwidth of 1-10 MHz, and the test step is:
* Within the 1-31.25mhz frequency range, the maximum step size is 0.1MHz;
* Within the 31.26-100mhz frequency, the maximum step size is 0.25MHz.
All tests should be carried out in line time test. For example, 4 pairs of lines to carry out 6 sets of tests.
Also, the test for next is tested at both ends. Next is not a measure of crosstalk generated at the near end, it is just a crosstalk value measured at the near endpoint. This measure decreases as the length of the cable decreases, and the signal at the distal end decays, and the crosstalk to the other line pairs becomes smaller. Experiments show that only 40 meters of the amount of next is more real, if the other end is far from 40 meters of information outlets and it will produce a certain degree of crosstalk, but the measuring instrument may not be able to measure the crosstalk, therefore, a two-way test must be conducted.