PLC programming is the essence technology of PLC, which largely determines the quality and function of a PLC. Today, PLC has been widely used in the production of various fields in the society, especially industrial production, and has undergone rapid development. We take a look at the oil, chemical and other industries around us. What are the main areas in which PLCs are used?
1, the amount of logic control
This is the most basic and widest application area of ​​PLC. It replaces the traditional relay circuit and realizes logic control and sequence control. It can be used not only for the control of a single device, but also for multi-machine group control and automated assembly lines. Such as injection molding machines, printing presses, staple machines, machine tools, grinding machines, packaging production lines, plating lines and so on.
2, motion control
PLC can be used for the control of circular motion or linear motion. From the point of view of the control mechanism configuration, the direct use of switch I/O modules in the early stage to connect position sensors and actuators now typically uses dedicated motion control modules. For example, a single-axis or multi-axis position control module that can drive stepper motors or servo motors. The products of major PLC manufacturers in the world have almost all motion control functions and are widely used in various machinery, machine tools, robots, elevators and other occasions.
3, data processing
Modern PLC basically has a precise high-end PLC programming language, with mathematical operations (including matrix operations, function operations, logic operations), data transmission, data conversion, sequencing, lookup table, bit operations and other functions, can complete the data collection, analysis And processing. These data can be compared with reference values ​​stored in memory to complete certain control operations. They can also be transmitted to other smart devices using communication functions, or they can be printed and tabulated. Data processing is generally used for large-scale control systems, such as unmanned flexible manufacturing systems; it can also be used for process control systems, such as large-scale control systems in the papermaking, metallurgy, and food industries.
4, communication and networking
PLC communication includes communication between PLCs and communication between PLC and other smart devices. With the development of computer control, the factory automation network has developed rapidly. All PLC manufacturers have attached great importance to the PLC communication function and have launched their own network systems. Newly produced PLCs all have communication interfaces and communication is very convenient.
5, process control
Process control refers to closed-loop control of temperature, pressure, flow, and other analog quantities. As an industrial control computer, PLC can compile various control algorithm programs to complete closed-loop control. PID regulation is a common adjustment method used in closed-loop control systems. Large and medium-sized PLCs have PID modules, and many small PLCs currently have this function module. PID processing is generally a dedicated PID subroutine. Process control has a very wide range of applications in metallurgical, chemical, heat treatment, boiler control and other occasions.
6, analog control
In the industrial production process, there are many continuously changing quantities, such as temperature, pressure, flow rate, liquid level, and speed, all of which are analog quantities. In order for the programmable controller to process analog quantities, A/D conversion and D/A conversion between Analog and Digital must be implemented. PLC manufacturers all produce matching A/D and D/A conversion modules, making programmable controllers for analog control.
PLC programming is the essence of PLC, and it is an essential part of it. In the high-tech industry, the development of the industry is more and more rapid, the demand for PLC in society will be more and more, learning PLC programming is imperative.