Programmable logic controller (PLC) is a real-time embedded computer for industrial control, which can realize various logic control and process control through a special control language. With PLC as the center, it can build an automatic control system for national defense and military industry, manufacturing, rail transit, electric power, water conservancy, municipal administration and other fields. The PLC system has become the "brain" of the modern digital industrial system, which can fully grasp all kinds of core process data and operation data, and directly determine and ensure the safe and healthy operation of the national industrial system and national defense equipment system.
1 The development status of PLC in China
In the past 60 years since the advent of PLC, it has realized the leap from relay wiring logic to storage logic in the field of industrial control, the function has changed from weak to strong, and the progress from logic control to digital control has been realized.
1.1 The development history of domestic PLC
Since the 70s of the 20th century, the R&D and application of PLC in China can be divided into four periods according to the development characteristics, namely the initial development period, the introduction and application period, the localization development period and the deep autonomy period, as shown in Figure 1. Initial development period. Since the mid-70s of the 20th century, the mainland has developed the first domestic PLC with practical value, which is applied to industrial production control.
In terms of the introduction of production lines, joint ventures were established to introduce foreign PLC production lines, such as the introduction of Siemens S5 series PLC production lines in 1986 and the PLC production line of AB Company established in 1988. In terms of the introduction of complete sets of equipment, the introduction of integrated imported PLC in the fields of steel, water conservancy and other fields has replaced the traditional relay to achieve logical control of the process, such as the introduction of more than 200 PLCs in the first phase of the Shanghai Baosteel project to achieve conveyor belt control, and the introduction of imported PLC in Shougang No. 4 blast furnace to achieve feeding, feeding and batching control. At the same time, under the organization of the Ministry of Machinery Industry in the 80s, the scientific research institutes represented by the Beijing Institute of Machinery Industry Automation began to develop the first generation of domestic PLC, and successively formed MPC-20, MPC-85, DJK-S-480 and other products.
Figure 1 Four stages of the development of domestic PLCs
Introduced application period. In the early 90s of the 20th century, the degree of domestic industrial automation is relatively low, the PLC market capacity is small, and PLC research and development needs to invest more money and manpower, and there is no return in the short term, some scientific research institutes turn to system integration, use imported PLC products to carry out control system engineering applications, imported PLC products gradually occupy the domestic market, Germany Siemens, the United States AB and other well-known brands of PLC began to enter the Chinese market in a big way, and the imported PLC market accounted for as much as 99%.
After 1995, the PLC market in mainland China formed a pattern in which large PLCs were mainly in Europe and the United States, small PLCs were mainly in Japan, and medium-sized PLCs were evenly divided between Europe and Japan. In 1991, the PLC Application Branch of China Mechatronics Application Association was established to promote PLC technology and product development, production and application. In 1993, the National Technical Committee for the Standardization of Industrial Process Measurement and Control Programmable Controller System SAC/TC124/SC5 was established to establish the standard system of programmable controllers and systems in the mainland, which laid the foundation for the development of PLC technology and industry in the mainland. Localization development period.
After entering the 21st century, with the rapid development of the domestic manufacturing industry, the demand for PLC has soared, and some enterprises have begun to enter the field after seeing market opportunities, developing and producing domestic PLC products, and have achieved large-scale applications in the fields of manufacturing, non-standard machinery, and power equipment. However, during this period, the domestic PLC was dominated by small PLC products, lacking core technology, and the basic parts were imported products, and the industrial scale was relatively small compared with foreign manufacturers. For example, in 2013, the domestic PLC market size was 7.8 billion yuan, and the domestic enterprise Wuxi Xinjie entered the top ten in the market with a market share of 1.6% with a cost-effective small PLC.
A period of deep autonomy. Affected by factors such as Iran's "Stuxnet Virus", "Prism Gate Incident", Ukraine's power outage, the U.S. Entity List and changes in the international situation, during the 13th Five-Year Plan period, the country took critical information infrastructure as the top priority of network security, and its control system PLC was incorporated into the network key equipment for management, opening the journey of in-depth localization of critical infrastructure control system. Domestic enterprises have overcome the key core technologies of PLC, developed independent safety PLC products based on domestic software and hardware platforms, and carried out promotion and application in energy fields such as power generation, rail transit, petroleum and petrochemical, such as the IM30 series PLC developed by the Sixth Institute of Electronics in 2020 in thermal power, wind power, municipal natural gas and other fields, realizing the deep localization of key infrastructure.
1.2 The status quo of the domestic PLC market
With the steady progress of Made in China 2025, the demand for automation systems continues to grow, as the core equipment of discrete control, the domestic PLC market size is increasing year by year, as shown in Figure 2, from 6.024 billion yuan in 2010 to 12.430 billion yuan in 2020 (PLC market size excluding distributed IO products is 10.850 billion yuan), the average annual growth rate in 10 years is 7.51%.
Figure 2 The trend of the domestic PLC market size in 2010~2020
According to the PLC model analysis, the market of large PLC has not changed much in the past 10 years, fluctuating up and down in the scale of 1.1 billion yuan/year, but with the development of the trend of pan-medium-sized, the performance of medium-sized PLC has been continuously enhanced, and some application scenarios of large-scale PLC have been replaced by medium-sized PLC, resulting in a steady and slightly declining trend in the large-scale PLC market. The medium-sized PLC market has grown steadily, with the market size increasing from 1.889 billion yuan in 2010 to 3.660 billion yuan in 2020, with an average annual growth rate of 6.84%. Due to the rapid growth of demand in OEM industry segments such as electronic manufacturing equipment, lithium battery equipment, photovoltaic equipment, semiconductor equipment, and packaging machinery, the market size of small PLC has increased significantly in recent years, from 2.733 billion yuan in 2010 to 6.070 billion yuan in 2020, with an average annual growth rate of 8.31%.
With the vertical integration of the industrial Internet into the industrial chain, PLC is widely used in automobile manufacturing, electrical and electronic industries, and the domestic PLC market will maintain stable growth in the next few years with the continuous advancement of intelligent manufacturing, and the PLC market size is expected to reach 14.46 billion yuan in 2022. An analysis of the PLC market size by brand is shown in Figure 3.
Figure 3 2016~2020 PLC manufacturers market size change trend
Siemens' market size and growth rate are far beyond other brands, and it has maintained the first place for a long time, while the Japanese Omron, Mitsubishi and the American Rockwell have maintained their ranking of 2~4 for a long time, and the top four rankings are relatively stable. With the increase in the size of the small PLC market, the market rankings of Delta and Xinjie have shown an upward trend, and Delta's market ranking in 2020 has entered the top five.
Figure 4 Domestic PLC market share in 2020
In 2020, the PLC market size in China will be 12.43 billion yuan, and the market share structure of PLC of each brand is shown in Figure 4 (a), Siemens ranks first with a market size of 5.31 billion yuan and a market share of 43%, and other manufacturers are Omron, Mitsubishi, Rockwell, Delta, Schneider Electric and other enterprises, and the above manufacturers account for about 90% of the market share. Only Xinjie, Inovance and Hollysys entered the top 10 among domestic enterprises.
In 2020, the market size of large-scale PLC will be 1.12 billion yuan, accounting for 10%; The PLC market size is 3.660 billion yuan, accounting for 34%, and the small PLC market size is 6.070 billion yuan, accounting for 56%, as shown in Figure 4 (b). Among them, large PLC manufacturers are mainly European and American manufacturers, and Rockwell, Siemens and Schneider rank among the top three in the large PLC market, accounting for 76.8% of the market share of the large PLC market, as shown in Table 1.
Table 1 PLC market size by brand in 2020 (100 million yuan)
In the medium-sized PLC market structure, Siemens is far ahead with a market share of 49.2%. The market size of Omron and Mitsubishi is more than 200 million yuan, forming the second echelon, accounting for a total of 29.2% of the market share. Rockwell and Schneider form the third echelon, accounting for 10% of the market share. The technical barriers to small PLC are low and the number of suppliers is large, but the top five manufacturers still occupy 74.3% of the market share, showing a competitive pattern of one large (Siemens) and four small (Omron, Mitsubishi, Delta, Wuxi Xinjie). In general, domestic PLC manufacturers have a certain competitiveness in the field of small PLC, and have entered the medium and large PLC market.
1.3 Status quo of domestic PLC products
There are more than 40 domestic PLC manufacturers, including Xinjie, Inovance, Hollysys, etc., after continuous efforts in recent years, domestic PLC has achieved remarkable results in technology, products and markets. The PLCs developed by Xinjie include XD/XC small PLC, XL thin card type and other series of PLCs, which are mainly used in small and medium-sized control scenarios in the fields of solar energy, tunnel engineering, textile machinery, power equipment, coal mining equipment, central air conditioning and other fields.
Inovance has developed a series of PLC products such as high-performance H3U, general-purpose H2U-XP, and economical H1U-XP, which are mainly used in elevators, air compressors, manipulators, 3C manufacturing and other fields. Hollysys has developed LE small PLC, LK medium and large PLC products and LKS safety PLC products, which are mainly used in OEM equipment such as packaging machinery and machine tools, as well as project-based industries such as municipal, tunnel, and rail transit. In addition to the above-mentioned enterprises, domestic enterprises have also developed and produced PLC products with their own characteristics, such as central control technology, Hexin, Yiwei, etc. In response to this problem, the enterprises represented by the six electronic institutes have developed independent PLC products based on domestic software and hardware platforms, such as the six electronic institutes using Feiteng CPU processors to develop IL40, IM30 and IS20 series of independent safety PLC products, which have been applied in batches in the fields of national defense and military industry, energy, municipal and other key infrastructure.
Although domestic PLC has made certain achievements, it is generally in a state of "small and weak". The market size of each manufacturer is small and the market share is low; The products are mainly small PLCs, and lack a complete product pedigree; Based on imported software and hardware products or the purchase of foreign control software to develop products, lack of core technology and advanced control software; The overall solution capability for the industry is weak; It has not formed the technology and market synergy of domestic PLC, and its competitiveness with foreign PLC manufacturers is weak.
1.4 Domestic PLC related standards
The standardization work in professional fields such as domestic PLC and system is responsible for the programmable controller and system sub-technical committee (TC124/SC5) of the National Technical Committee for Industrial Process Measurement, Control and Automation Standardization, and the China Machinery Industry Federation provides business guidance.
The domestic PLC related standards are mainly GB/T15969 series standards, which were first released in 1995 under the guidance of the Ministry of Machinery Industry of China, centralized by TC124/SC5, which is equivalent to the adoption IEC61131 of international standards. As of 2022, the officially released GB/T15969 includes 9 parts.
Part 1 is general information that defines the main functional features of the PLC system. Part 2 is equipment requirements and tests, specifying the requirements of the PLC and related tests. Part 3 is the programming language, which specifies the syntax and semantics of the PLC programming language. Part 4 is the User Guideline, which provides some basic rules for the exchange of information between PLC users and PLC suppliers. Part 5 is Communication, which defines the communication between a PLC and other electronic systems. Part 6 is functional safety, including functional safety PLC safety life cycle management, functional safety requirements assignment and development planning. Part 7 is fuzzy control programming, which defines the programming language used for fuzzy control. Part 8 deals with programming languages and provides guidelines for the application and implementation of programming languages defined in Section 3. Part 9 specifies single-point digital communication interfaces for small sensors and actuators. Part 10 is the PLC open XML exchange format, which specifies an XML-based exchange format for the export and import of GB/T15969.3 projects, which has completed the consultation and is in the process of review.
In addition to the GB/T15969 series of standards, relevant standards have also been formulated in PLC function evaluation, information security and engineering integration. GB/T36009 stipulates the performance indicators, testing and evaluation methods of PLC, and provides a basis for the performance evaluation of PLC. GB/T36011 specifies the sampling inspection methods and routine test methods for the appearance, IO function, communication and other tests related to the environmental adaptability of the PLC before leaving the factory. GB/T37391 stipulates the conditions for the use and functional requirements of PLC complete sets of control equipment. In view of the information security protection capability of PLC, GB/T33008.1 and the "Information Security Technology Programmable Logic Controller (PLC) Security Technical Requirements and Test and Evaluation Methods" that are being submitted for approval stipulate the PLC network security requirements and test methods, of which GB/T33008 and GB/T33009 and other standards together constitute a series of standards for industrial automation and control system network security; GB/T41274 describes the objectives of endogenous safety of PLC system and the related safety requirements of each unit module from the aspect of endogenous safety requirements.
In terms of the industrial application of PLC, GB/T40329 stipulates the programming language and semantics of PLC programming language for CNC equipment PLC in industrial machinery and electrical equipment and systems, and the syntax and semantics of special module programming; GB/T37761 specifies the relevant requirements for PLC control devices for power transformer cooling systems. In terms of national military standards, the first PLC national military standard "General Specification for Military Programmable Control Systems" began to be drafted in 2020, and has now been compiled and is in the approval stage.
1.5 Domestic PLC related policies
In recent years, with the gradual expansion of the scope of the European and American entity lists and the frequent occurrence of industrial security incidents, the state attaches great importance to the information technology application innovation industry in the field of industrial control, and has successively introduced a series of supporting policies and plans to realize the independence of key core technologies. The state is also extremely concerned about the safety and controllability of PLC, and autonomy and network security have become "keywords", and the release of corresponding policies has promoted the healthy and orderly development of the domestic PLC industry, and some policies are shown in Table 2.
Table 2 PLC related policies
Supporting the policy, the state attaches great importance to the scientific research investment in the industrial control system, and has successively set up PLC projects in major projects such as the National High-tech Research and Development Program (863 Program), the National Science and Technology Major Project (Nuclear High-tech Base), and the National Key R&D Program (Network Security Special, Manufacturing Technology and Key Components Special, etc.), so as to improve the ability to improve the capacity from multiple directions such as PLC large-scale system, safety protection, safety and controllability, promote the research and promotion and application of PLC key technologies, and accelerate the realization of self-reliance and self-improvement of the PLC industry. Some PLC-related scientific and technological projects are shown in Table 3.
Table 3 PLC-related science and technology plans and major projects
2 PLC gap analysis at home and abroad
With the promotion and application of domestic PLC in different fields, domestic PLC has made certain breakthroughs in application technology, but there are still shortcomings, and compared with foreign PLC, there is still a large gap in functional performance, ease of use, reliability, etc.
In terms of functional performance, the high-performance PLC products of mainstream foreign PLC manufacturers usually use customized dedicated SoCs and real-time running software to improve the performance of instruction processing, data storage, data exchange and control output from the underlying platform. Domestic PLC products usually borrow general-purpose information system processors and general-purpose embedded systems, and most of them adopt the low-performance and low-cost design scheme of "general-purpose CPU + software". Because general-purpose processors are usually oriented to the design of information computers and conventional embedded systems, the system is redundant, the useless functions of basic software and hardware are more, and the underlying support of chips and software is lacking in real-time, advanced control algorithms and other functions, resulting in the difficulty of developing and upgrading PLC special functions, small optimization and improvement space, low control efficiency, and weak overall performance.
In terms of logic programming software, foreign PLC logic programming software usually integrates functions such as monitoring and driving execution, which realizes the integrated design capability of engineering, strong ease of use and high efficiency of engineering development. Most of the domestic PLC logic programming software adopts the kernel of foreign general products such as CoDeSys, KW-Software or OpenPCS, which only considers the programming and development requirements of PLC itself, and cannot be integrated with other control systems to achieve integrated development, and the integration workload of third-party system is large, the operation is complex, the ease of use is poor, and the engineering development efficiency is low. For example, Siemens logic programming software Portal TIAPortal integrates PLC programming software Step7, PLC simulation software PLCSIM and monitoring software WinCC, etc., which can efficiently configure control points and monitoring points, and the control variables are available in the global project, while the domestic PLC and other systems need the control variable points and monitoring variable points of the logic programming software to be frequently imported and exported to realize the interaction and communication with other systems, and the engineering efficiency is low.
In terms of communication protocols, most of the PLC products of foreign mainstream manufacturers adopt self-developed communication protocols, and under the background of perfect independent ecology, the compatible interconnection between the upper monitoring layer and field instruments and actuators is realized through one network. Foreign manufacturers only form the conventional protocol part into IEC international standards or open source code, and do not disclose the protocol and code for complex applications. Domestic PLC manufacturers lack the ability to develop independent communication network protocols, and most of them directly use IEC standards or industrial fieldbuses based on open source code. Domestic PLC is subject to established standards, it is difficult to modify and optimize the protocol indicators, customized development is difficult, access to the actuator needs to increase the conversion interface, reduce the system response time, often in complex control applications found that the function is insufficient or the performance is not enough, resulting in product expansion and adaptability is greatly limited.
In terms of product spectrum, in addition to PLC products, foreign mainstream manufacturers also provide upstream and downstream software and hardware automation products with complete pedigree, which can quickly form an integrated solution covering core products such as perception, execution, control, and monitoring. Domestic PLC manufacturers usually only provide PLC products, with a single product line, lack of supporting upstream and downstream automation products, imperfect spectrum, difficult to provide system-level overall solutions, and unable to form a product system synergy at the level of product technology and market competition. The overall solution in China is generally built with products from different manufacturers, and there are differences in product interfaces, function definitions, quality standards, etc., and the matching between products is not as good as that of the same foreign manufacturer's products, which cannot optimize the overall performance, control efficiency and reliability from the system level, and at the same time increases the complexity of system design and the difficulty of debugging. At the same time, it is also difficult for control system engineers to achieve one-stop procurement when selecting domestic products.
In terms of standardization, after decades of accumulation and development, foreign PLC manufacturers have formed a large industrial scale, and in the case of occupying market advantages, they have led the formulation of a perfect standard system covering automation systems, including international standards or industry standards such as control technology, information security, and functional safety, and have mastered the right to speak in the industry. At present, although some PLC technical standards have been formulated in China, the existing standards are basically equivalent to foreign standards, lack of top-level planning, have not yet formed a standard system, and are subject to established foreign technical standards, resulting in less independent innovation of domestic PLC, unable to lead the development of technology through standards, lack of competitiveness in market competition, and weak industry discourse.
3 "Chinese system" PLC development ideas
At present, PLC can be divided into three major schools according to geography: European, American and Japanese, which have different characteristics in terms of product positioning, functional performance, logic programming and market layout. European PLCs are represented by Siemens and Schneider, American PLCs are represented by Rockwell and General Electric, and Japanese PLCs are represented by Mitsubishi and Omron.
In view of the gap between the development of PLC at home and abroad, combined with the development status of domestic PLC, this paper puts forward the development idea of "Chinese system" PLC. Corresponding to the three major schools of PLC, "Chinese" PLC is a domestic PLC product based on the characteristics of the domestic market and application scenarios, based on the development of domestic independent software and hardware, with native safety capabilities, in line with the usage habits of domestic engineers, and to meet the needs of domestic diversified industrial control applications.
3.1 General
The R&D background, application needs and market positioning of European, American and Japanese PLC products are obviously different, resulting in different product characteristics and market distribution of the three series PLCs. European and American PLCs are innovation-led, powerful, and well-known for medium and large PLCs, with a complete product pedigree. The function of the European PLC is strong, the programming method is rigorous, and the ease of use is slightly weaker. American PLC pays attention to functional practicability, has many function blocks, and the programming method is relatively uncomplicated.
European and American PLCs are mainly used in the field of major equipment and key infrastructure, and the project-based market share is high. Japanese PLC is market-oriented, known for its small PLC, with high product integration, programming close to traditional electrical control, and general function. Japanese PLC is mainly used in small and medium-sized electromechanical automation equipment, and the OEM market share is high. "Chinese-system" PLC should focus on the application of national defense and military industry and key infrastructure, benchmark European PLC, take into account the characteristics of strong economy and high integration of Japanese PLC, establish a domestic PLC ecology through the leading role of major equipment and key areas, and then gradually promote it to other fields.
3.2 Market Conditions
In terms of market distribution, for the overall market size, European PLCs accounted for about 47.4% in 2020, the largest market size, American PLCs accounted for about 7%, and Japanese PLCs accounted for about 21.6%. Among them, European and American PLCs occupy the vast majority of the market share of medium and large PLCs, and Japanese PLCs maintain a high market share in the small PLC market. Rockwell in the United States, Siemens in Europe and Schneider account for 76.8% of the large PLC market share. European Siemens is a leader in the medium-sized PLC market, and the market pattern has been relatively stable for a long time, accounting for more than 50% of the market. Japanese Omron, Mitsubishi and Germany's Siemens account for 56% of the small PLC market share. From the perspective of realizing the in-depth localization of key infrastructure, "Chinese-based" PLC should first aim at the medium and large PLC product market.
From the perspective of product price, European and American PLCs are mainly medium and large PLCs, which are more powerful and have higher added value, so the price is higher. In particular, the American AB brand PLC, the Japanese PLC is mainly small PLC, positioned as an economical product, cost-effective, and the price is relatively low. Considering the ecological characteristics, product index capabilities and application scenario characteristics of domestic basic software and hardware, the price of "Chinese" PLC is positioned in the middle, lower than that of Europe and the United States, and slightly higher than that of Japanese PLC products.
From the perspective of industry distribution, European and American PLCs are mainly project-based markets, and PLC products are applied in the integration project of the control system, and the overall automation system of the project is designed and implemented. Japanese PLCs are mainly used in the OEM market, and PLCs are assembled into equipment and sold in batches along with the equipment.
European PLC has a complete product line, reliable quality, mature channel network and excellent solution capabilities, almost all user industries have applications, and in the electric power, metallurgy, rail transit, automobile manufacturing and other major fields have strong competitiveness and high market share, such as in the field of hydropower, almost monopolized by the French Schneider PLC. With its strong functional performance and the support of the most leading system integrators in various industries, American PLC has a high market share in the municipal, oil and gas, metallurgy, electric power, pharmaceutical and food markets. With its outstanding cost performance, constantly innovating product series, and high functional integration, Japanese PLC is widely used in almost all OEM industries that use small PLC products, including food machinery, packaging machinery, textile machinery, machine tools, electronic manufacturing equipment, HVAC, etc. "China-based" PLC focuses on applications in fields related to the national economy and people's livelihood, including military equipment, military manufacturing and other national defense and military industries, as well as key infrastructure fields such as electric power, water conservancy, petroleum and petrochemical, metallurgy, and municipal administration.
3.3 Product Features
European and American PLC products focus on process control and communication control, while Japanese PLC focuses more on discrete control and motion control. The medium and large PLC products of the "Chinese system" PLC focus on process and discrete control, and the small PLC focuses on motion control.
From the perspective of process control, the European PLC supports complex floating-point operations, has advantages in analog accuracy, realizes simple control logic procedures, and can quickly and easily realize closed-loop control PID and other algorithms, which has obvious advantages in the field of process control. Japanese PLCs are mainly based on integer calculation, and the analog programming is complex, and special control modules need to be added to achieve complex control, which is costly.
From the perspective of motion control, Japanese PLCs usually have dedicated positioning instructions to achieve servo control and stepper movement, making it easier to achieve complex motion control, such as robotic arm control. However, European and American PLCs lack special motion control instructions, need to write complex programs, and the control accuracy is not high.
From the perspective of communication capabilities, European and American PLCs mostly use open industrial communication protocols, or provide communication protocol chips, which are easy to access third-party equipment. The network protocol of Japanese PLCs is usually relatively closed, and only supports the company's products, making it difficult to access third-party devices.
3.4 Control Logic Programming
The programming of European and American PLCs is closer to the thinking of computer programming. PLC is an industrialized special computer, PLC programming draws on the general and simple means of computer programming and the simple way of computer data calculation, and the programming is more concise and clear. European and American PLCs are mainly structured programming, with more complete hierarchy and structure, with rich function blocks, program blocks, and organization blocks, which are convenient for invocation and reuse, high readability, and easy to locate faults and debug. Some European and American PLCs also support high-level language programming, such as C language, which has obvious advantages when writing large-scale control programs. However, the instructions of PLC are relatively abstract, there is a certain threshold for programming to get started, and engineers need certain basic computer knowledge.
Japanese PLC has more graphical programming concepts, and most of the data processing is separated from the basic storage concept and format of computer data processing, and the programming is intuitive and easy to use. Japanese PLCs usually adopt a single vertical structure from top to bottom, including the main program and sub-programs, the hierarchy and structure are not strong, and many programs need to be put together. PLC programming is inefficient, and the interpretation of results is cumbersome. Therefore, Japanese PLC can be competent for small and medium-sized control systems, and programming and debugging in large-scale systems are cumbersome and complex, and it is difficult to achieve efficient and fast programming and manufacturing. The "Chinese" PLC should mainly refer to the characteristics of European and American PLC programming software, and draw on the graphical programming concept of Japanese PLC, so as to achieve intuitive programming and configuration that can not only meet the requirements of complex control scenarios.
Considering the characteristics of the domestic PLC market and user habits, in terms of product pedigree, product characteristics and product application, "Chinese" PLC is based on the development of domestic software and hardware, benchmarking European PLC products, first, in the product pedigree, it has a perfect spectrum of large, medium and small PLC products, and mainly medium and large high-end PLC; Second, in terms of product characteristics, it has high-end functions such as hot standby redundancy, advanced control algorithms, nanosecond instruction processing speed, microsecond synchronization accuracy and other advanced performance to meet the application needs of complex scenarios. Third, in the application of products, we will play a leading role in key areas related to the national economy and people's livelihood such as national defense and military industry and key infrastructure in advance, and gradually promote and apply them to other fields after forming a certain ecology.
4 Conclusion
This paper summarizes the four stages of domestic PLC development, and introduces the development status of domestic PLC from the aspects of market status, product status, standards and relevant policies and plans promulgated by the state. Then, this paper analyzes the gap between domestic PLC and imported PLC products, and puts forward the development idea of "Chinese" PLC benchmarking with European, American and Japanese PLCs in combination with the current situation in China.
Disclaimer: This article is transferred from the Internet, the copyright belongs to the original author, if it involves the copyright of the work, please contact us to delete it in time, thank you!
How can I get more information about electrical hot topics?
Here's how to do it!