51305896-200 NIM MODEM HONEYWELL 停产备件 Programmable controller is a new generation of industrial control device developed based on microprocessor and integrated computer, communication, networking and automatic control technology. The development and application of programmable logic controller in my country has a history of more than 30 years. Now it has been widely used in various industrial production fields of the national economy, and has become an important equipment and a strong pillar to improve the level and technical capabilities of traditional industrial equipment. With the development of the global integrated economy, efforts to develop large-scale application of programmable logic controllers in our country, and to form programmable logic controller technology with independent intellectual property rights, should be the direction of the efforts of the majority of technicians.
The development history of programmable logic controllers
The programmable logic controller came out in the 1960s. At that time, the functions of the programmable logic controller were very simple, only logic, timing, counting and other functions; the integrated circuits used for the programmable logic controller in hardware have not been put into large-scale investment. In industrial production, the CPU is composed of discrete components; the memory is a magnetic core memory with limited storage capacity; there are generally only twenty or thirty user instructions, and no programming language has been formed; the model is single, and there is no series. A programmable logic controller can only replace a control system consisting of 200 to 300 relays at most. Compared with the current programmable logic controller, it can be said to be a behemoth in terms of volume.
In the 1970s, with the industrial production of small and medium-sized integrated circuits, programmable logic controller technology has been greatly developed. In addition to logic operations, the functions of programmable logic controllers have added numerical operations, computer interfaces, analog control, etc.; software development has a self-diagnostic program, and EPROM has been used for program storage; the reliability has been further improved, and a series has been initially formed. The distinction between modular and integral, the function of the whole machine transitions from dedicated to general.
In the late 1970s and early 1980s, microprocessor technology became more and more mature, single-chip microprocessors and semiconductor memories entered industrial production, and large-scale integrated circuits began to be widely used. Programmable controllers began to develop towards multiprocessors, which greatly enhanced the function and processing speed of programmable controllers, and had communication and remote I/O capabilities, adding a variety of special functions, such as floating-point operations, trigonometric Functions, look-up tables, lists, etc., self-diagnosis and fault-tolerant technologies are also developing rapidly.
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