Description
The Programmable Logic Controller was first introduced in the United States in the late 1960s, when it was called the Programmable Logic Controller (PLC), which was used to replace relays. To perform logical judgment, timing, counting and other sequential control functions. The concept of PLC was proposed by General Motors. The basic design idea of PLC is to combine the advantages of computer function perfect, flexible, universal and relay control system simple and easy to understand, easy to operate, cheap and so on, the controller hardware is standard and universal. According to the actual application object, the control content is compiled into software and written into the user program memory of the controller, so that the connection between the controller and the controlled object is convenient. PLC features and functions (1) The main characteristics of plc. The characteristics of plc are: reliable work, fast running speed, building block structure, flexible combination, good compatibility, simple programming and generation, rich, strong network function. (2) The main functions of plc. plc system can well complete the industrial real-time sequence control, condition control, counting control, step control and other functions; It can complete analog/digital (a/d), digital/analog (d/a) conversion, data processing, communication networking, real-time monitoring and other functions. Years of practice shows that plc, reliable, is designed for the factory, with reinforced components according to the requirements of the working environment, real-time scanning practice and fault diagnosis function, easy troubleshooting, won the preference of users. What makes a plc so reliable is a real-time core or operating system of executable relay logic, sequential function diagrams, function blocks, structured text, command catalogs, or a combination thereof. In case of failure, the built-in device can maintain mechanical damage and maintain an orderly and predictable sequence. 2.4 The development trend of plc: there are extremely fast logical operations and logic control, sequence control capabilities, reliability in discrete control, convenient and easy to learn programming methods, so that it has an undisputed position in the field of industrial automation based on discrete.
Application field of PLC At present, PLC has been widely used in steel, petroleum, chemical, electric power, building materials, machinery manufacturing, automobile, textile, transportation, environmental protection and cultural entertainment and other industries at home and abroad, the use is mainly divided into the following categories: 1. Switch quantity logic control Instead of the traditional relay circuit, it can realize logic control and sequence control, which can be used for the control of a single device, and can also be used for multi-machine group control and automatic pipeline. Such as injection molding machines, printing presses, stapler machines, combined machine tools, grinding machines, packaging production lines, electroplating lines, etc. 2. Industrial process control In the industrial production process, there are some continuous changes such as temperature, pressure, flow, liquid level and speed (that is, the analog amount), PLC uses the corresponding A/D and D/A conversion modules and a variety of control algorithms to deal with the analog amount, complete closed-loop control. PID regulation is a kind of regulation method used in general closed-loop control system. Process control is widely used in metallurgy, chemical industry, heat treatment, boiler control and so on. 3. Motion control PLC can be used to control circular or linear motion. Generally use special motion control modules, such as single-axis or multi-axis position control modules that can drive stepper motors or servo motors, widely used in various machinery, machine tools, robots, elevators and other occasions. 4. Data processing PLC has mathematical operations (including matrix operations, function operations, logical operations), data transmission, data conversion, sorting, table lookup, bit operation and other functions, can complete the data collection, analysis and processing. Data processing is generally used in some large control systems in the paper, metallurgy, and food industries. 5. Communication and networking PLC communication includes communication between PLC and communication between PLC and other intelligent devices. With the development of factory automation network, PLC now has a communication interface, communication is very convenient.
Application characteristics of PLC 1. High reliability, strong anti-interference ability High reliability is the key performance of electrical control equipment. Due to the use of modern large-scale integrated circuit technology, PLC adopts strict production process manufacturing, the internal circuit adopts advanced anti-interference technology, with high reliability. The use of PLC to form a control system, and the relay contactor system of the same size, electrical wiring and switch contacts have been reduced to hundreds or even thousands of one, the fault is greatly reduced. In addition, the PLC has a hardware fault self-detection function, which can issue alarm information in time when there is a failure. In the application software, the user can also program the fault self-diagnosis program of peripheral devices, so that the circuit and equipment other than PLC in the system can also obtain fault self-diagnosis protection. In this way, the whole system will be extremely reliable. 2. Complete set, perfect function, strong applicability PLC development to today, has formed a variety of scale of serialized products, can be used in various scales of industrial control occasions. In addition to logic processing functions, PLC mostly has perfect data computing capabilities and can be used in various digital control fields. A large number of various functional units have emerged, so that PLC has penetrated into various industrial controls such as position control, temperature control, CNC. With the enhancement of PLC communication capability and the development of human-machine interface technology, it is very easy to use PLC to form various control systems. 3. Easy to learn and easy to use, welcomed by engineering and technical personnel PLC is an industrial control equipment for industrial and mining enterprises. Its interface is easy and the programming language is easy to be accepted by engineers and technicians. The graphic symbol of ladder diagram language is quite close to the expression mode and relay circuit diagram, which opens the convenient door for people who are not familiar with electronic circuits, do not understand computer principles and assembly language to engage in industrial control. 4. The design of the system has the advantages of small workload, convenient maintenance and easy transformation PLC replaces wiring logic with storage logic, which greatly reduces the wiring outside the control equipment, greatly shortens the cycle of control system design and construction, and makes daily maintenance easier, more importantly, it is possible to change the production process after changing the program of the same equipment. This is especially suitable for multi-variety, small batch production occasions.
The company focuses on DCS, PLC, robot, large servo four systems
The main products are various modules/cards, controllers, touch screens, servo drivers Company advantage: Supply imported original products, professional production of spare parts One year warranty, fast delivery time, complete supply !！！ ① 24 hours email response (12 hours); ② For shipment outside Asia, please contact the seller.
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