PLC USES the working mode of circular scanning, in THE PLC user program is stored in sequence, the CPU starts from the first instruction to execute the program, until it encounters the end character and then returns the first, so the cycle continues.
PLC scanning process is divided into internal processing, communication operation, program input processing, program execution, program output several stages.
The time required to scan the whole process once is called the scanning period.
When THE PLC is in a stop state, only internal processing and communication operation services and other contents.
In the running state of PLC, from the internal processing, communication operation, program input, program execution, program output, has been a cycle of scanning work.
After the program is executed, the output image register, that is, the state of the Y register in the device image register, is transferred to the output latch in the output processing stage. Through the isolation circuit, the power amplifier circuit is driven to make the output terminal output control signal to the outside world and drive the external load.

Programmable logic controller (PLC) is a kind of electronic computer specially designed for industrial control. Its hardware structure is basically the same as the component unit of microcomputer, and its functions such as storage, recording and control are realized through programming.
PLC controller technology content high, large storage space and a lot of original programming, according to the characteristics of wide customers, and strong control function is very apparent distance according to different purposes in different areas constantly expanding, yuan through special skills of application integration, can show its high flexibility and good generality and can effectively control for all kinds of industrial machinery.



At present, the application of industrial automatic PLC system is still in its infancy, so it is necessary to constantly improve the theoretical research of PLC technology and promote the continuous improvement and optimization of technology.

1. Strengthen the in-depth RESEARCH and development of PLC technology

PLC technology comes out in innovation and develops in innovation.
Strengthening the DEPTH of THE RESEARCH and development of PLC technology is to expand its application, improve the localization rate of software and hardware, constantly improve the theoretical system of the application of control debugging system, make up for the existing defects in PLC technology, make the industrial automation PLC control system more intelligent.

2. Establish PLC technical application and debugging standards

The use of PLC technology of all walks of life is different, control content and application range are not the same.
Therefore, it is necessary to accelerate the application of PLC technology and the formulation of debugging standards.
With a unified standard, in order to facilitate the cooperation between industries.
All industries should cooperate with each other to improve technical standards, quality standards, testing standards, etc., to promote the standardization process of PLC technology.

3. Strengthen the communication between the designer and the user

No matter where THE PLC technology is used, there is a problem of communication between the designer and the user.
To make THE PLC technology more in line with the purpose of practical use, the use of problems in the process of more timely feedback information to the designer, in order to promote the continuous improvement and optimization of the technology.

Science and technology have no end.
With the development of PLC technology and the continuous expansion of the application market, it will be applied to a wider range of fields.
The application of PLC technology in industrial automation has just started, and its application in life has a broad prospect. In the future, it will realize a qualitative leap from the leap in quantity.
In order to adapt to the arrival of the new era, there is more knowledge to explore, there are many mountains to climb.