I. INTRODUCTION
In the field of modern industrial automation, PLC (Programmable Logic Controller) control system has attracted much attention because of its powerful functions, high reliability and wide range of applications.PLC control system not only combines microelectronics technology, computer technology, automatic control technology and communication technology, but also realizes the automation control of industrial equipments through programming control. automated control of industrial equipment, greatly improving production efficiency and reducing production costs. In this paper, we will introduce the basic concept of PLC control system, working principle, functional characteristics, structural composition and application areas in detail.
II. The basic concept of PLC control system
PLC control system is a program control device, which controls the state of input/output (I/O) signals through pre-written programs, thus realizing automatic control, monitoring and operation of field equipment.PLC control system is developed on the basis of traditional sequence controller, which replaces the sequence control functions such as relays, execution logic, timekeeping, counting, etc., and establishes a flexible remote control system.
III. The working principle of PLC control system
The working principle of PLC control system mainly includes the following steps:
Input signal acquisition: PLC control system receives signals from sensors, switches, buttons and other external devices such as temperature, pressure, position, speed, etc. through the input module. These signals reflect the actual state of the industrial production site.
Signal processing: The PLC control system processes the acquired signals accordingly, including signal filtering, amplification, transformation, comparison, etc., to ensure the reliability and correctness of the signals.
Logic operation: PLC control system carries out logic operation on the processed signals, such as with, or, not, etc., and judges whether the control conditions are established or not according to the preset logic relationship.
Output control: If the control conditions are established, the PLC control system sends out control signals to external devices such as actuators, motors, valves, etc. through the output module to realize the control of the industrial production process.
Monitoring and feedback: PLC control system for real-time monitoring of the control process, collect feedback information, according to the feedback information for the adjustment and optimization of the control parameters to ensure the safety, reliability and efficiency of the industrial production process.
IV. PLC control system features
PLC control system has the following significant functional characteristics:
Strong versatility: PLC control system has a standardized programming language and communication interface, can be easily connected and communicated with other equipment and systems.
Easy to use: PLC control system programming is intuitive and easy to understand, the user can write the appropriate control program according to the actual needs, to achieve a variety of complex control functions.
Wide adaptability: PLC control system can be applied in various industrial automation fields, such as manufacturing, transportation, petrochemical, electric power system and so on.
High reliability: PLC control system adopts microprocessor and memory and other electronic components, which has high reliability and stability and can run stably for a long time.
Strong anti-interference ability: PLC control system has a strong anti-interference ability, can effectively resist electromagnetic interference and noise interference, to ensure the normal operation of the system.
V. Structure of the PLC control system composition
PLC control system structure mainly consists of the following parts:
Power supply components: used to provide the power supply required for PLC operation, the external power supply will be converted to power for internal use of the PLC.
Microprocessor CPU and memory components: microprocessor CPU is the core device of the PLC, responsible for the execution of the control program; memory components including ROM and RAM, used to store programs and data.
Input and output components: input and output components are PLC and industrial production site to exchange data interface, used to receive signals from external devices and send control signals to external devices.
VI. Application areas of PLC control system
PLC control system is widely used in industrial automation control field, including but not limited to the following areas:
Manufacturing: PLC is widely used in the automation control of production lines in the manufacturing industry, such as automated assembly lines, automated packaging lines, automated spraying lines, automated welding lines and so on.
Transportation: PLC can be used in the control of traffic signals, control of baggage conveyor systems in stations and airports, control of automated cargo transportation systems, etc.
Petrochemical: PLC can be used for process control, safety monitoring, real-time monitoring and adjustment of temperature, pressure, liquid level and other parameters in petrochemical production process.
Power system: PLC can be used for automation control of power system, including control and protection of substation, monitoring of transmission lines, grid scheduling and so on.
Sewage treatment: PLC can be used for automated control of sewage treatment process, including regulating water flow, regulating pressure, controlling water level, sewage treatment process control and so on.
VII. Conclusion
PLC control system as an important part of the modern industrial automation field, with its powerful functions, high reliability and wide range of applications has won wide recognition and application. With the continuous development and progress of technology, PLC control system will play a more important role in the field of industrial automation in the future.