Programmable logic controller
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Programmable logic controller The early machines were made up of cams, gears, levers, and some other basic mechanical equipment. With the increasing complexity of the machine, also need a more complex control system to control the connection function modules of this system includes the control switch and relay, these modules according to the needs of some logic functions and some specific types of machine operation group are connected into a whole, which is not a need to change the hardware but with the improvement of production technology can be easily ported to new products, with the majority of equipment upgrades can easily control machines, change circuit switching and switching logic is very cumbersome and time consuming, for the production of a new circuit to change the control scheme and reconnect is inevitable, modify it very the difficulties and design up to spend a lot of time, some small problems in the process of installing the design will become the lead line Systems need to be redesigned for key factors must be re modify the control circuit, the American auto industry lead the development and promotion of the new technology, became a leading figure in the industry as a whole, this new technology in the late 1960s and early 1970s obtained vigorous development, from the birth programming controller, also known as PLC, automobile manufacturing industry facing manufacturing process of all-round improvement, such as improvements in some aspects must be linked to other aspects, PLC provides a simple method by re programming instead of the line of the whole system as a whole change. In the program development during the development of the PLC system is not an easy thing, for the design of PLC programming language is a very troublesome thing, this work requires an experienced programmer and trained with regularity to complete, early device functions only by frequent change of relay to achieve PLC, PLC now gradually, the rapid development in recent years has become a complex and highly versatile control system components, each module has the ability to perform complex mathematical functions including integral and differential operation, these functions are through a fast microprocessor, old PLC discrete input and output (i.e. switch input signal) today, the system can receive and generate analog voltage and current, wide level and pulse signal, the PLC design process is very difficult, Unlike in the existing computer technology based on the design of the new computer can easily withstand the external environment such as vibration, shock, temperature rise, and the interference of electromagnetic noise. With more and more manufacturers involved in the company's production and development, PLC function expand rapidly, programming language also great rich, this is the development of every new thing must go through the process, also various manufacturers tend to develop their own ladder logic language (for a PLC programming language). This complex PLC language can not applicable to all types of equipment. However, with the other computer languages like, once this ladder language has been widely used, then the language being used in most of the equipment on the possibility is big, most of the system designers will find production of a particular manufacturer of products for the writing system. It should be noted that the programmable logic controller is often referred to as "PLC" or "programmable controller". Although the term "programmable logic controller" has been widely accepted, it is not like the abbreviation "personal computer", because the abbreviation "personal computer" usually refers to the personal computer used. In this article we will see that PLC does not mean personal computer. Can be programmable controller is the personal computer users as free many configuration options, as personal computers selected which is better some completely rely on their own experience, as a controller of a lot of setup options to good control it made him work needs to rely on their own experience.。Modular PLC including the system components are: 1 processor Processor (sometimes referred to as CPU) is a program of the central processor can execute, which is full of the module with a number of specific features, these features some processing more complex mathematical operations and some of the PID control loop and programmable command processor is composed of a micro processor, a system memory, serial communication port and printer, PLC LAN links and external programming equipment system through the I / O port supply. 2 Architecture