1) PROFIBUS PROFIBUS was the strength of five research institutes of 13 companies in Germany in 1987. The German national standard for fieldbus was developed in accordance with the ISO/OSI reference model. Its main supporter is Siemens AG in Germany. It was published in DIN 19245 in April 1991 and officially became a German standard. In the beginning, only PROFIBUS-DP and PROFIBUS-FMS were introduced. In 1994, PROFIBUS-PA was introduced again. It refers to the IEC standard physical layer (IEC 1158-2, passed in 1993) so that it can be located in explosion-hazardous areas (EX). Connecting intrinsically safe field instruments fed via the bus makes PROFIBUS perfect. PROFIBUS was approved on March 15, 1996 as volume 2 of the European standard EN50170. (1) PROFIBUS components. 1 PROFIBUS-FMS (Field Message Specification). It is mainly used to solve the general-purpose communication tasks at the plant level and can be used for large-scale and complex communications. The bus cycle is generally less than 100ms. 2PROFIBUS-DP (Decentralized Periphery). This is an optimized high-speed and inexpensive communication bus designed specifically for communication between automatic control systems and decentralized I/O design levels. The bus cycle is generally less than 10ms. 3PROFIBUS-PA (Process Automation). It is designed specifically for process automation. It allows sensors and actuators to be on a common bus, even in intrinsically safe areas. According to the IEC 1158-2 standard, PROFIBUS-PA uses two wires for bus power and data communication. (2) PROFIBUS protocol structure. The PROFIBUS protocol structure is based on the IS0 7498 international standard with OSI as a reference model. However, the 3-6th layer was omitted and the service layer was added. PROFIBUS-DP uses the first layer (physical layer), the second layer (data link layer), and the user interface. The third layer and seven layers are not described. This structure ensures fast and efficient data transmission. Direct Data Link Mapping (DDLM) is easy for the user interface to enter the second layer. The user interface stipulates the application functions that the user system and different devices can call, and describes in detail the device behavior of various different PROFIBUS-DP devices, and also provides RS-485 transmission technology or optical fiber transmission technology for transmission. PROFIBUS-FMS: Defines the first layer, the second layer, and the seventh layer (application layer). PROFIBUS-PA: The extended DP protocol is used, and a process automation (PA) specification describing the behavior of field devices is also used. According to the IEC 115 8-2 standard, this transmission technology ensures its essential security and powers field devices via the bus. With segmented couplers, PROFIBUS-PA devices can be easily integrated into PROFIBUS-DP networks. PROFIBUS-DP and PROFIBUS-FMS systems use the same transmission technology and a unified bus access protocol, so that the two systems can operate simultaneously on the same cable. (3) PROFIBUS transmission technology. PROFIBUS offers three types of transmissions. 1 RS-485 transmission for DP and FMS. RS-485 transmission is the most commonly used transmission technology of PROFIBUS. This technology is usually called H2. Shielded twisted-pair copper wire is used to share one wire pair. The linear bus architecture allows sites to increase or decrease, and the system's distributed effort will not affect the operation of other sites. After the increase of the site has no effect on the site has been put into operation. The transmission rate is optional: between 9.6Kbit/s and 12Mbit/s. Number of stations: 32 stations per segment without repeaters; Up to 127 stations with repeaters. 2 for PA and Ji c 1158-2 transmission. The IEC 1158-2 transmission technology is a bit synchronization protocol that allows continuous transmission without current, commonly referred to as H1. Transmission rate: 31.25Kbit/s, voltage type. Number of sites: Up to 32 per segment, with a total of up to 126. Distance: Twisted-pair cable is used and the transmission distance is up to 1900m. 8 optical fibers (FO). When PROFIBUS systems are used in environments with high electromagnetic interference, fiber optic conductors can be used to increase the maximum distance for high-speed transmission. Many manufacturers provide dedicated bus plugs that convert RS-485 signals into optical signals and optical signals into RS-485 signals, which is why RS-485 and optical fiber transmission technologies are similar. - The use of the system provides a very simple way of controlling a switch. 2) Foundation Fieldbus (FF) The Fieldbus Foundation is an international organization with more than 120 members, including suppliers of the world's major process control products, transmitters, DCS systems, actuators produced by Foundation members, and flow meters representing the world market. 90%. FF was forced by the pressure of the user in June 1994 by the ISP and WorldFIP (North America) merger established Fieldbus Foundation. ISP is the abbreviation of Interoperable System Protocol. It is based on the German PROFIBUS standard and was established in September 1992. At that time, more than 100 companies participated, among which there were many instrument manufacturers, led by Fisher Rosemount. WorldFIP is the abbreviation of the World Factory Instrumentation Protocol. It is based on the French FIP standard. It is led by Honeywell Corporation and also attended by more than 100 companies. Many are PLC manufacturers. (1) FF's protocol structure. FF applies the first, second, and seventh layers (application layer) of the ISO/OSI model, and then adds the user layer to the application layer. The physical layer of the FF complies with the IEC 115 8-2 standard and uses the IEC 1158-2 technology. (2) FF features. Because some of the world's largest instrument companies have participated in FF, FF developed fieldbus products can meet the requirements of process control in terms of variety and performance, and easy to use, FF has a good interoperability and interchangeability Sexuality and interoperability means that devices from the same manufacturer can communicate with each other and can perform functions in a multi-factory environment. Interchangeability means that devices from different manufacturers can be exchanged by similar devices in terms of functionality. (3) Application. In 1997, a small test system based on the H1 standard provided by a number of suppliers was used for training and technical confirmation and has been tested in the world. Now it is also used in smart homes, and it has a good technical support for the development and application of smart homes. For more information on smart security alarm product price and background music system joining , please click to read!
We are professional manufacturer of various kinds of casters .The most professional production, the most safe and durable caster is that we adhere to the concept of High Quality and Mutual Benefit
With casters production enterprises of since its inception, specializing in the production of industrial casters, scaffolding caster for 20 years. In the past 20 years, we have rich experience in design and production standards, won a good reputation at home and abroad. With casters to customers in North America, Europe, Asia, Australia, South Africa and the Middle East, we experience also let us understand the needs of the international market, fast delivery and safe use. The company has 150 units/sets of production equipment, 2 pouring PU production line, 2 rubber vulcanization production line , 10 sets of large-scale injection molding equipment, automatic welding equipment, equipped with professional level of production to modernize. Using the fully and semi-automatic machinery to achieve excellence in technology and the production of consistency; Research and development team using advanced CAD/CAM software and three-dimensional software design OEM caster; Equipped with professional mold development workshop, by professional engineers to adjust the existing model, constantly updated design, so as to adapt to the changing demands of customers at home and abroad; By professional personnel in accordance with the strict product inspection standards for all products are factory inspection, to ensure the high quality of the products.
We produce PU casters and rubber casters, high bearing capacity, the use of lightweight flexible, but won't hurt smooth floor .Special process increases the stability and the security of the load, the high quality raw materials and advanced processing technology, ensure with casters do not come unglued, no crack, more wear-resisting ;Processing with galvanized metal stents or plastic spraying Metal , make the caster wheel bracket is not easy to rust.
Light Duty Casters,Lower Gravity Casters,Medium Heavy Casters,Industrial Casters,Extra Heavy Duty Casters,Shock Absorb Casters,Mute Casters BAODING JIMAOTONG IMPORT AND EXPORT CO., LTD , https://www.chinagroundscrew.com
