The hottest PLC has a long way to go

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There is a long way to go for the development of PLC

PLC has been produced for more than 40 years, and the potential of PLC market is still very huge. In China, the proportion of electromechanical integrated products supported by PLC has increased year by year, and the proportion of users using conventional relays and other control products has gradually shrunk. In the development trend of PLC, the most noticeable is networking and intellectualization, including the introduction of Ethernet and other bus technologies, and the introduction of fuzzy control, machine vision and other technologies into PLC, which greatly enriches the application scope of PLC and improves the living space of PLC. In this issue, Mr. Ying Rongliang, deputy manager of the wind power project Department of Hollysys, will be interviewed to discuss the development trend and application status of PLC

(1) PLC initially appeared to complete the control strategy, in order to replace the relay and enable users to complete the ladder diagram of the control system similar to the relay circuit, so most of them use ladder diagram to program. However, with the gradual increase of the complexity of mechatronics products, when many ladder diagrams cannot correctly complete the final programming work, other programming languages will gradually be liked by the public. How do you think about ladder programming and other programming methods

Ying Rongliang: at present, most industries of PLC still belong to traditional logic control occasions, and ladder diagram still has great advantages in such applications, which is intuitive and simple. At present, ladder diagram language is still the programming language with the largest number of applications and the widest application industry. However, with the improvement of control requirements, the function and application scope of PLC are gradually expanding. PLC data processing ability is becoming stronger and stronger, analog quantity application is more and more, logic control is more and more complex, points are more and more, and programming is more and more large. Under this application, PLC is required to have not only ladder diagram and other languages of traditional PLC, but also structured text st language and SFC language of sequence function diagram similar to high-level language. Similar to computer high-level language, St language supports sentences such as judgment and loop, and has great advantages in dealing with some complex calculations and algorithms. SFC language is a sequential function diagram, which can be controlled in sequence according to the process. It is more suitable for the field of process control with more points and standardized steps. St language and SFC language are important supplements to ladder language. They are also an indispensable part of PLC programming language in the future

(2) in 1968, GM (General Motors) put forward the requirement to replace the relay control device. In the second year, Digital Corporation of America developed the first programmable controller, which met the requirements of GM's assembly line. With the development of integrated circuit technology and computer technology, there are now fifth generation PLC products. What do you think is the development trend of PLC? What new products will your company launch

Ying Rongliang: now PLC has the following development trends:

1. PLC functions are more and more subdivided. There are more and more individual needs in the industry, especially in Small PLC. A product is often used in some industries, and the situation that a product dominates the world will basically not appear again

2. The boundary between large PLC and small PLC is getting blurred. With the development of computer technology, the data processing ability and communication ability of Small PLC have been greatly enhanced. In 200, many small PLCs can also meet the requirements because such products can also realize the application of automatic production points to about 300 points

3. The requirements of network communication function are higher and higher. On the one hand, why is this? What are the reasons?, With the requirements of networking and integration, PLC needs to be more and more connected to the computer monitoring network as a node of the network. On the other hand, intelligent instruments are more and more widely used, so PLC is required to have more field bus interfaces to communicate directly with intelligent instruments

4. User experience requirements are getting higher and higher. Due to the popularity of computers, more users begin to accept some operating habits of computers, so higher requirements are put forward for PLC, especially programming. Users require friendly interface, convenient and flexible operation, upper and lower levels can share the same database, and programming is simple and easy to learn

in view of the above trends, Hollysys, after full market research and technical development, will soon launch Le series PLC to the market for the machinery and equipment supporting industry, which has greatly improved its point taking ability, communication function, motion control ability, etc. compared with previous products

hexply m21e/ima prepreg of Hexcel company is used by Tata advanced materials to manufacture beams and composite plates of Airbus A350 XWB (3) IEC has formulated the programming language standard IEC based on windows, which should be said to be the international standard of PLC. What do you think of this standard? Does your company's product implement this standard

Ying Rongliang: the introduction of IEC has standardized the standard of PLC programming software and unified the user's use specification, so that users do not need to invest a lot of time to learn software programming when using PLCs from different manufacturers. This is of great benefit to the promotion of PLC

since the first PLC, Hollysys' programming software has always followed the IEC software standard. In the future, we will still develop according to this standard to provide users with better products

(4) some people say that the upward connection of the network is an interconnection problem, and the downward connection is a fieldbus problem. How do you think of the PLC network and bus problem

Ying Rongliang: a development trend of PLC is networking. On the one hand, the requirements of networking and integration make PLC need to be more and more connected to the computer monitoring network as a node of the network, so PLC is required to have Ethernet communication ability. On the other hand, intelligent instruments are more and more widely used, so PLC is required to have more field bus interfaces to communicate directly with intelligent instruments

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