TThe-characteristics-of-PLC

1、1、 PLC can be programmed controller (Programmable logic Controller, refers to computer technology as the basis for the new industrial control devices. In 1987 the International Electrotechnical Commission (International Electrical Committee) standards promulgated by the PLC in the draft of the PLC m

2、ade the following definition : "PLC is a specialist in industrial environments for the application of digital design and operation of electronic computing devices. It can be used in the preparation process memory, used in the implementation of its internal storage logical, sequential computing,

3、 timing, counting and arithmetic operations such as Operation The directive, and through digital or analog input and output, control various types of machinery or production process. PLC and its related peripheral equipment should be in accordance with the industrial control system easy to form a wh

4、ole, easy to expand its functions to the principle And design. " The characteristics of PLC 2.1 high reliability, strong anti-interference capability High reliability of electrical control equipment is the key to performance. PLC due to the introduction of modern large-scale integrated circuit

5、technology, rigorous production process, the internal circuitry to take an advanced anti-jamming technology, high reliability. For example, Mitsubishi has produced an average of the F-Series PLC trouble-free time as much as 300,000 hours. Some use the redundant CPU PLC, the average working hours of

6、trouble-free longer. PLC from the machine outside the circuit, the use of a PLC control system, and equal access for the scale of the relay systems, electrical wiring and switch contact has been reduced to hundreds or even 0.1 percent, fault also greatly reduced. In addition, PLC with self-detection

7、 hardware failure, a failure to timely warning information. In the application software, applications can also peripheral devices into the fault diagnosis procedures, in addition to the system PLC and equipment outside the circuit fault diagnosis also be protected. In this way, the whole system is e

8、xtremely high reliability is also not strange. 2.2 equipped, with perfect functions, the applicability PLC to develop today, has formed a large, medium and small size of the serialization of various products. Can be used for various industrial control the scale of occasions. Apart from the logic pro

9、cessing functions, most of the modern PLC has a complete data computing power and can be used for a variety of digital control of the area. In recent years PLC emergence of a large number of functional units so that the PLC to infiltrate into a position of control, temperature control, CNC, and othe

10、r industrial control. PLC communication capabilities coupled with the strengthening of human-computer interface technology and the development and use of various PLC control system very easily. 2.3 easy to learn and use, welcomed by the engineering and technical personnel PLC as the general industri

11、al computer, industrial and mining enterprises are facing the industrial equipment. It easy interface, easy programming language for engineering and technical staff. Ladder language and graphic symbols and expressions of the relay circuit very close, only a small number of switches of the PLC logic

12、control orders can easily achieve the functions of the relay circuit. Is not familiar with the electronic circuits, computers do not understand the principles and compilation of language people use computers to carry out industrial control opened the door. 2.4 system design, construction workload of

13、 small, maintenance-friendly, easy to transform PLC logic with memory instead of wiring logic, greatly reducing the wiring outside the control equipment, control systems design and construction of the much shorter cycle, while maintaining it has become easier. What is more important is to make the s

14、ame equipment have been changes in procedures to change the production process possible. This is very suitable for many species, the small batch production of occasions. 2.5 small size, light weight, low energy consumption To ultra-small PLC for example, recently produced at the bottom of the specie

15、s size smaller than 100 mm, weight of less than 150 g, only a few watts power consumption. As small size can easily into the internal mechanical, electrical and mechanical integration is to achieve the ideal control equipment. 3. PLC applications At present, PLC at home and abroad has been widely us

16、ed in iron and steel, petroleum, chemicals, power, building materials, machinery manufacturing, automotive, textile, transport, environmental protection and cultural entertainment, and various other industries, use can be broadly grouped into the following categories. 3.1 switch to the logic of cont

17、rol This is the most basic PLC, the most extensive areas of application, which replaced the traditional relay circuits, and logic control, sequence control, can be used single-control device, can also be used for more automation and control aircraft assembly line. Such as injection molding machines,

18、 printing presses, Dingshu machinery, machine tools portfolio, grinders, packaging production line, such as electroplating lines. 3.2 analog control In the course of industrial production, many of the continuous changes, such as temperature, pressure, flow, level and speed are all analog. In order t

19、o deal with programmable analog controller, the need to achieve analog (Analog) and digital (Digital) between the A / D converter and D / A converter. PLC manufacturers are supporting the production of A / D and D / A converter module so that the programmable logic controller for analog control. 3.3

20、 Motion Control PLC can be used circular motion or linear motion control. From the control of institutions targeted, the switching capacity for early direct I / O modules position sensor and executive bodies, now generally used for the movement control module. Such as stepper motor drive servo motor

21、 or the location of single or multi-axis control module. PLC the world's major manufacturers of products almost all movement control, widely used in all kinds of machinery, machine tools, robots, elevators, and other occasions. 3.4 Process Control Refers to the process control temperature, press

22、ure, flow simulation of the closed-loop control. As industrial computer, PLC to the preparation of a variety of control algorithms procedures, complete closed-loop control. PID regulator is generally closed-loop control system used in more conditioning methods. PID modules are large and medium-sized

23、 PLC, the PLC also has many small feature of this module. PID is running for the processing of PID subroutine. Process control in the metallurgical, chemical, heat treatment, boiler control, and other occasions have a very wide range of applications. 3.5 Data Processing Modern PLC with math (includi

24、ng matrix computing, computing functions, logic operation), data transmission, data conversion, sorting, look-up table, in operation, and other functions, to complete the data collection, analysis and treatment. These data can be stored in the memory of the reference value, the completion of a contr

25、ol operation, can also use the communication sent to other intelligent devices, or print them tabulation. Data processing for large-scale control systems such as unmanned control of flexible manufacturing systems; can also be used for process control systems, such as paper making, metallurgy, food i

26、ndustry in some large-scale control system. 3.6 communications and networking PLC communication with the communications between the PLC and the PLC and other smart devices communication. With the development of computer control, factory automation network have developed rapidly, the PLC manufacturer

27、s have attached great importance to the PLC communications, have launched their own network system. The newly produced PLC has communication interface, communication is very convenient. 4. PLC domestic and international situation in industrial production processes, a large number of switch the order

28、 of control, in accordance with the logic of its order of conditions for action and follow the logic of action for the protection of chain control, and a large number of discrete data acquisition. Traditionally, these functions through pneumatic or electrical control system to achieve. 1968 U.S. GM

29、(General Motors) companies to replace the electrical control devices following the requirements of the second year, the U.S. company Digital Equipment (DEC) has developed a technology-based integrated circuits and electronic control devices, the first use of the means of application procedures In th

30、e electrical control, and this is the first generation of programmable logic controller, said Programmable, is the world's first recognized the PLC. 360毕业设计网友情提供-     Limited to conditions at the time of the components and computer development, early PLC mainly by discrete co

31、mponents and small and medium-scale integrated circuit components, can complete a simple logic control and timing, counting function. In the early 1970s a microprocessor. People will soon introduce its programmable logic controller, PLC an increase of computing, data transmission and processing func

32、tions, complete with a real computer features of industrial control devices. In order to facilitate familiar with the relay, contact the system engineering and technical staff, and the PLC adopt a similar ladder relay circuit as the main programming language, and will participate in the operation of

33、 the computer storage and processing components are named to the relay . At this time of the PLC for computer technology and relay the concept of combining conventional control of the product. Personal computer (PC) to develop, in order to facilitate, as well as to reflect the features of programmab

34、le logic controller, PLC known as the Programmable Logic Controller (PLC).      20 in the late 1970s, the PLC into a practical stage of development, the introduction of computer technology has been fully programmable logic controller, to function in a leap. The higher speed of co

35、mputing, ultra-small size, the more reliable anti-jamming industrial design, analog computing, PID function and a high price for it in modern industry's position. In the early 1980s, programmable logic controller in the advanced industrial countries has been widely used. During this period PLC d

36、evelopment is characterized by large-scale, high-speed, high-performance, product serialization. Another feature of this stage is the world's production of the PLC countries have increased, rising output. This marks the PLC has entered a mature stage. In the 1980s to the mid-1990s, the PLC is th

37、e fastest-growing period, the annual growth rate has been maintained for 30 to 40 percent. In this period, PLC capability in dealing with analog and digital computing power, network capacity and human-computer interface capacity of a substantial increase, PLC is entering the field of process control

38、, in some applications replaced in the field of process control in the ruling position DCS system. The late 20th century, the development characteristics of programmable logic controller is more adapted to the needs of modern industry. From the control of scale, this period of development of the mai

39、nframe and ultra-Xiao Xingji, from the ability to control, the birth of a variety of special function modules for pressure, temperature, speed, displacement, such as various kinds of control Occasions; products from the supporting capacity, the production of a variety of man-machine interface unit,

40、communications unit, so that the application of programmable logic controller supporting industrial control equipment more easily. At present, the PLC in machinery manufacturing, petrochemicals, iron and steel metallurgy, automobiles, light industry and other fields of application have been develope

41、d by leaps and bounds. China's introduction of the PLC, applications, development, production is accompanied by reform and opening up began. The first is the introduction of large-scale use of the equipment in the PLC. Next in the production of business equipment and products continue to expand

42、the application of the PLC. At present, China has its own can produce small and medium-sized PLC. East Electric Co., Ltd. Shanghai housing production CF Series, Hangzhou Machine Tool Factory production of electrical and DKK D series, Dalian Machine Tool Institute combination of the S-Series producti

43、on, the Suzhou plant production of computers and other products YZ series has a certain scale And access to industrial products in the application. In addition, Wuxi Huaguang Company, Shanghai Rural Island companies such as Sino-foreign joint ventures in China is relatively well-known manufacturer o

44、f the PLC. It can be expected, with the deepening of China's modernization process, PLC in China will have a wider application of heaven and earth. 5. PLC Future 21, PLC will have a greater development. From a technical perspective, the new achievements in computer technology will be applied to

45、more programmable controllers on the design and manufacture, there will be faster and faster, greater storage capacity, more intelligent species emerged from the products on the scale , Will be further to the ultra-small and super-large direction, from the matching of products, the products of the s

46、pecies will be more rich and more complete specifications, the perfect man-machine interface, improved communications equipment will be better adapted to various industrial control Occasions demand from the market, the production of their respective countries and more varieties of products will be a

47、 country's development situation, programmable controllers and other industrial control of a large computer network control system is PLC Technical direction of development. The current computer distributed control system DCS (Distributed Control System) has been a lot of programmable logic cont

48、roller applications. Along with the development of computer networks, automatic control programmable logic controller as a common network and international network an important part in industry and industrial fields outside of the increasing role. The composition of 1.2 PLC From the structural point

49、s, PLC is divided into fixed and modular (modular) two. Fixed PLC board, including CPU, I / O board, display, memory blocks, power supplies, the combination of these elements into a whole is not removable. Modular PLC, including CPU module, I / O modules, memory, power modules, floor or rack, these

50、modules can be configured according to certain rules of composition. 1.3 CPU components PLC CPU is the core, from the nerve center of the role, at least one each at the PLC CPU, which according to the PLC system to process the function of the user to receive and store programs and data, collected by

51、 scanning the way from the scene input device sent to the state Or data, and deposited under the register, at the same time, the power of PLC and the work status of the internal circuitry and programming in the process of grammatical mistakes, and so on. Access to running, from the user memory in the process one by one to read instructions, then click the command of the mandate set out to produce the control signals, to command the control circuit. CPU mainly by the operator, co