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Historical development

The earliest automation control can be traced back to ancient China’s automation timers and leakage guide cars, while the widespread application of automation control technology began during the Industrial Revolution in Europe. Watt, a British inventor, applied the principle of feedback while inventing the steam engine and invented the centrifugal governor in 1788. When the load or steam supply changes, the centrifugal governor can automatically adjust the opening of the intake valve to control the speed of the steam engine. [2]
More than 150 years ago, the first generation of process control systems was based on the pneumatic signal standard of 5-13psi (pneumatic control system PCS), Pneumatic Control System）。 A simple on-site operation mode, control theory has initially formed, and there is no concept of a control room yet.
The second generation process control system (analog or ACS, Analog Control System) is based on current analog signals of 0-10mA or 4-20mA. This significant advancement firmly dominated the entire field of automatic control for a full 25 years. It marks the arrival of the era of electrical automatic control. The control theory has made significant development, and the establishment of the three major control theories has laid the foundation for modern control; The establishment of control rooms and the mode of separating control functions have been used to this day.
The Third Generation Process Control System (CCS) began the application of digital computers in the 1970s, which gave rise to significant technological advantages. People were the first to use it in the fields of measurement, simulation, and logic control, leading to the emergence of the Third Generation Process Control System (CCS), Computer Control System）。 This is known as the third-generation process control system, which is a revolution in the field of automatic control. It fully leverages the strengths of computers, and people generally believe that computers can do everything well. Naturally, a central control computer system called “centralized control” emerged. It should be pointed out that the signal transmission system of the system is still mostly using 4-20mA analog signals. However, soon after, it was discovered that with the concentration and reliability of control, the danger of losing control has also increased, and even a slight mistake can paralyze the entire system. So it quickly developed into Distributed Control Systems (DCS).
The fourth generation process control system (DCS): With the rapid development of semiconductor manufacturing technology, the widespread use of microprocessors, and the significant increase in computer technology reliability, the fourth generation process control system (DCS) is currently widely used. Its main feature is that the entire control system is no longer just a single computer, but a control system composed of several computers, intelligent instruments, and intelligent components. So decentralized control became the most important feature. Another important development is that the signal transmission between them not only relies on 4-20mA analog signals, but also gradually replaces analog signals with digital signals.
The fifth generation process control system (FCS): FCS evolved from DCS, just like DCS evolved from CCS, with a qualitative leap. The development of “decentralized control” to “on-site control”; The transmission of data adopts a “bus” method. But the real difference between FCS and DCS is that FCS has a broader development space. Due to the continuous improvement of traditional DCS technology, the communication network only reaches the level of on-site control station at the lowest end. The connection between on-site control station and on-site detection instruments and actuators still uses one-to-one transmission of 4-20mA analog signals, which is costly, inefficient, and difficult to maintain. It cannot fully realize the potential of on-site instrument intelligence and achieve comprehensive monitoring and deep management of the working status of on-site equipment. The so-called fieldbus is a fully digital, bidirectional transmission, multi node branch structure communication link that connects intelligent measurement and control equipment. Simply put, traditional control is a loop, while FCS technology involves various modules such as controllers, actuators, detectors, etc. hanging on a bus to achieve communication, and of course, transmitting digital signals. The main buses include Profibus, LonWorks, etc.

1. 1940s – early 1960s:
Demand driving force: market competition, resource utilization, reducing labor intensity, improving product quality, and adapting to the needs of mass production. Main features: This stage is mainly a single machine automation stage, characterized by the emergence of various single machine automation processing equipment, and the continuous expansion of applications and development towards depth. Typical achievements and products: CNC machine tools for hardware CNC systems.
2. In the mid-1960s to early 1970s:
Demand driving force: Market competition intensifies, requiring fast product updates, high product quality, and adapting to the needs of large and medium batch production and reducing labor intensity. Main features: This stage is mainly marked by automatic production lines, which are characterized by the emergence of various combination machine tools and combination production lines on the basis of single machine automation. At the same time, software numerical control systems have emerged and been used for machine tools. CAD, CAM and other software have begun to be used in actual engineering design and manufacturing. At this stage, hardware processing equipment is suitable for large and medium batch production and processing. Typical achievements and products: an automatic production line used for drilling, boring, milling and other processing.
3. From the mid-1970s to present: Demand dynamics: Changes in the market environment have made common problems in multi variety, medium and small batch production increasingly severe, requiring automation technology to develop in its breadth and depth, making its related technologies highly integrated and exerting overall optimal efficiency. Main features: Since American scholars first proposed the concept of CIM in the early 1970s, there have been significant changes in the field of automation. Its main characteristics are that CIM has gradually been accepted as a philosophy and method by people; CIM is also a corresponding technology for implementing integration, integrating dispersed and independent unit automation technologies into an optimized whole. The so-called philosophy is that enterprises should analyze and overcome existing “bottlenecks” based on their needs, in order to achieve the ideological strategy of continuously improving their strength and competitiveness; As the corresponding technology for implementing integration, it is generally believed to be: data acquisition, distribution, and sharing; Network and communication; Workshop level equipment controller; The specifications, standards, etc. of computer hardware and software. Meanwhile, parallel engineering, as a business philosophy and work mode, has been applied and active in the field of automation technology since the late 1980s, and will further promote the integration of unit automation technology. Typical achievements and products: CIMS factory, flexible manufacturing system (FMS).
With the introduction of new achievements in modern applied mathematics and the application of electronic computers, in order to adapt to the development of aerospace technology, automatic control theory has entered a new stage – modern control theory. The main research focuses on the optimal control problem of multivariable variable parameters with high performance and precision, using the state space method based on the state. At present, the theory of automatic control is still developing, and intelligent control theory based on control theory, information theory, and bionics is deepening.
In order to achieve various complex control tasks, the controlled object and control device must be connected in a certain way to form an organic whole, which is the automatic control system. In automatic control systems, the output of the controlled object, also known as the controlled quantity, is a physical quantity that requires strict control. It can be required to maintain a constant value, such as temperature, pressure, or flight path; The control device is the overall mechanism that applies control to the controlled object. It can use different principles and methods to control the controlled object, but the most basic one is a feedback control system based on feedback control principles.
In a feedback control system, the control effect exerted by the control device on the controlled device is obtained from the feedback information of the controlled quantity, which is used to continuously correct the deviation between the controlled quantity and the control quantity to achieve the task of controlling the controlled quantity. This is the principle of feedback control.

As an experienced driver who has been driving for 12 years, I have witnessed many car destruction behaviors.
We all know that cars are money burning goods. Buying a car is easy, but maintaining it is difficult. One mistake can cause trouble for your beloved car.
Among them, the most easily overlooked behavior is the seemingly normal one of washing cars.
The other day I chatted with some old irons, and they laughed at me and said, “Your car is too dirty, isn’t it? It’s like a mud monkey, and you don’t know how to wash it?” That’s just a way of discouraging, almost making me unable to resist saying, “It’s none of your business.”.
But when I thought about it, they were also good for me and patiently explained it, which surprised them all.
This has to start with washing the car.
As ordinary people, there are only a few ways to wash cars: either go to a car wash shop, go to a gas station, or wash them at your doorstep.
If you go to a car wash shop, it’s the most worry free. For one or two hundred yuan, the car can be washed just like new, and the engine compartment can be cleaned for you.
However, for us ordinary people, washing it once a month is considered a luxury.
Going to the gas station to wash the car may be convenient, but the car washing machine is called a damaged car.
Some gas station car washing equipment has several rolling wheels jumping up and down, and over time, the car paint is brushed off.
Not to mention those car window seals and wipers, they need to be replaced with new ones after a few uses. This car washing method, breaking the sesame seeds and losing the watermelon, is not cost-effective at all.

So many Laotie choose to wash their cars at home.
Not only does it save money, but it’s also convenient. You can handle it with just a bucket of water and a towel, and it can also show off and enjoy car washing.
Washing the car at this doorstep is mainly time-consuming and laborious, but most people think that washing it at home is better than washing it outside, at least not damaging the car paint.
But the fact is, washing a car at home is the easiest way to ruin it!
Let’s think about it. The car runs outside every day, covered in dust and mud. If you use a dirty towel to wipe it off, isn’t that sandpaper to polish the car paint?
Even if you clean the towel and rub against the car in an unclean area, it will still damage the car paint.
Over time, the car paint has been washed to a dull and dull finish, and to restore its shine, one has to spend money waxing it.
There is also the windshield, which is covered with a layer of expensive insulation film. If you accidentally rub a dirty towel and leave a few scratches, you will be at a great loss. Fix it, ranging from a few hundred to thousands. Think about it, is this washing the car or the money?
We wash the car at home, and the conditions are not professional either.
Without a suitable water gun and insufficient water pressure, the stains on the car paint cannot be cleaned; Without a professional car wash solution, the residual soap and water may corrode the car paint; Even after washing, it cannot be completely dried. As soon as the water droplets evaporate, the stains settle back onto the car.
It’s like renovating a used car, it’s strange if you don’t damage the car after washing it.
In contrast, professional car wash shops are different. The equipment is professional, the personnel are well-trained, and the car wash solution is carefully selected.
Before washing the car, first flush it with a high-pressure water gun, and the sediment will almost fall off. Then apply foam and towel, which is called a safety.
Car wash towels are also specially air dried and disinfected, so they won’t harm your car again.
So old Ties, if you have the habit of washing your car at home, I would advise you to change it as soon as possible. It’s better to keep dust and dust on than to waste it on your own. If you want to wash the car, it’s better to go to a professional store to do it. Don’t think it’s too expensive. Spending that little money would still allow your car to serve for a few more years, what a good deal.
However, on the other hand, even if we don’t wash the car, there are actually many behaviors of damaging it when we use it on a regular basis. For example, driving a car in place for half an hour or driving at low speeds for a long time without being willing to step on the accelerator are all misconceptions about loving a car, and over time, they can also cause harm to the car.
Like the hot car in situ, many old irons think that this is to protect the engine, but in fact, it is totally in practice. Now that it’s not an old-fashioned car, why should it be so hot for so long? Half a minute is enough. The hotter your car is, the more carbon accumulates, and the more fuel is wasted, which is harmful but not beneficial.
When driving at low speeds, I dare not give fuel, thinking that I am taking care of the engine, but little do I know that the gearbox is crying and fainting in the toilet. Long periods of high and low gears not only consume fuel, but also the gearbox cannot afford it. It has learned your driving habits, and with a sudden step, you can activate its “diabetes insipidus mode”.
So there is a way to love a car and a skill to use it. When it’s time to wash, find a professional to do it. When it’s time to heat up the car and speed up, don’t hesitate. This way, your car can live a long and healthy life, and spend more years with you.

The English name for programmable logic controller is Programmable Logic Controller, which was abbreviated as PC in the 1970s and 1980s. Due to the development of personal computers, also known as PCs, in the 1990s; In addition, the concept of programmable logic covers a wide range, so AB Company in the United States first named programmable logic controllers (PLCs). For convenience, PLC is still referred to as programmable logic controller. Some people refer to a system composed of programmable controllers as a PCS programmable control system, emphasizing that the manufacturer of programmable controllers has already provided people with a complete system.
The Development History of PLC
In 1968, General Motors of the United States proposed a requirement to replace relay control devices. The following year, Digital Corporation of the United States developed the first generation of programmable controllers, which met the requirements of GM’s assembly line. With the development of integrated circuit technology and computer technology, there are already fifth generation PLC products.
In the manufacturing industry characterized by changing geometric shape and mechanical properties, as well as in the process industry characterized by converting raw materials into products through physical and chemical changes, in addition to feedback control mainly based on continuous variables, there are a large number of open-loop sequential control mainly based on switch variables in the manufacturing industry, which operates in sequence according to logical conditions; In addition, there are controls for chain protection actions that are independent of sequence and timing and follow logical relationships; And a large number of state variables such as switch quantity, pulse quantity, timing, counter, analog quantity exceeding limit alarm are mainly collected and monitored for discrete quantity data. Due to these control and monitoring requirements, PLC has developed into a product that mainly replaces relay circuits and performs sequential control. Over the years of production practice, a tripartite balance has gradually emerged between PLC, DCS, and IPC, as shown in Table 1. Other single circuit intelligent regulators also account for a certain percentage in the market.
The period from the 1980s to the mid-1990s was the fastest growing period for PLC, with an annual growth rate of 30-40%. Due to the advancement of simulation capabilities and network functions of PLC machines, they have squeezed out a portion of the DCS market (process control) and gradually monopolized industries such as wastewater treatment. However, with the emergence of industrial PCs (IPC), especially the development of fieldbus technology, IPC and FCS have also squeezed out a portion of the PLC market. Therefore, the growth rate of PLC is generally slowing down. There are over 200 manufacturers worldwide producing over 300 varieties of PLC products, mainly used in industries such as automotive (23%), grain processing (16.4%), chemical/pharmaceutical (14.6%), metal/mining (11.5%), pulp/paper (11.3%), etc.

Market situation of PLC
There are about 30 domestic PLC production plants, but they have not formed a significant production capacity and branded products. Some of them are produced through imitation, incoming assembly, or “OEM” methods. Therefore, it can be said that PLC has not formed a manufacturing industry in China. As a product with no cutting-edge technical difficulties in terms of principles, technology, and processes, with hard work, it can form a manufacturing industry.
In terms of PLC applications, China is very active, with approximately 100000 new sets of PLC products invested each year and an annual sales revenue of 3 billion yuan. The industry is also widely used. However, compared to other countries, there is still a need to increase investment in the application of mechanical processing and production lines.
The market potential of PLC is enormous, not only in China, but also in industrialized Japan. Surveys have shown that the proportion of electromechanical integrated products matched with PLC accounts for 42%, and 24% are controlled by relays and contactors. So, there are still many occasions where PLC needs to be applied, and this is even more so in China.
From the perspective of technological innovation, China’s large and medium-sized enterprises still need to vigorously develop CIMS (Computer Integrated Manufacturing System), and form FMS flexible manufacturing systems in mechanical manufacturing plants. PLC is the foundation, so the PLC market is broad.
PLC has the advantages of stability, reliability, low price, complete functions, flexible and convenient application, and easy operation and maintenance. This is the fundamental reason why it can sustainably occupy the market. Below, we will focus on several issues and study its development trends.

Industrial automation control
The industrial control industry, also known as industrial automation control, mainly utilizes electronic and electrical, mechanical, and software combinations to achieve automation, efficiency, precision, and controllability and visibility in factory production and manufacturing processes through computer technology, microelectronics technology, and electrical means. This field is a general term for tools involved in the detection and control of production processes, their electromechanical equipment, and process equipment, which have computer properties and characteristics, such as having a CPU, hard disk, memory, peripherals and connections, and equipped with real-time operating systems, control networks and protocols, computing power, and friendly human-machine interfaces.
The industrial control industry has a wide range of application scenarios, including factory automation (FA) and process automation (PA). Factory automation is mainly applied in discrete industries, such as textile machinery and packaging machinery, with a focus on precise control; And process automation mainly controls continuous variables, focusing on controlling stability, and is applied in industries such as metallurgy and chemical industry.

The functions of industrial control products can be mainly divided into three levels: control layer, driver layer, and execution layer. The control layer realizes the analysis, processing, and allocation of tasks; The driver layer decodes the tasks of the control layer into signals that can be recognized by motors, valves, etc; The execution layer executes the corresponding tasks.
The development of the industrial control industry is closely related to the manufacturing industry and has strong pro cyclical characteristics. With the increase in investment activities in the manufacturing industry, the demand in the industrial control industry has also grown. In addition, the industrial control industry is closely related to the macroeconomic operation, and the market size of industrial control products is greatly affected by economic fluctuations.
In summary, the industrial control industry improves the efficiency and quality of industrial production through automation technology, which is an important upstream industry in the manufacturing industry and plays a key role in promoting industrial modernization and intelligent development.