The main application occasions of PLC

Today, PLC is not only used for switch control, but also for analog and digital control, which can collect and store data, and monitor the control system; it can also be connected to the Internet and communicate to achieve large-scale, cross-regional control and control. manage. PLC has increasingly become an important role in the family of industrial control devices.

1. Switch logic control

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 automatic assembly line. Such as injection molding machines, printing machines, staplers, combination machine tools, grinding machines, packaging production lines, electroplating lines, etc.

2. Industrial process control

In the process of industrial production, there are some continuously changing quantities such as temperature, pressure, flow, liquid level and speed (that is, analog quantities). PLC uses corresponding A/D and D/A conversion modules and various control systems of various schools. The algorithm program is used to process the analog quantity and complete the closed-loop control. PID adjustment is an adjustment method that is widely used in general closed-loop control systems. Process control is widely used in metallurgy, chemical industry, heat treatment, boiler control and other occasions.

3. Motion Control

PLC can be used for the control of circular motion or linear motion. Generally, special motion control modules are used, such as single-axis or multi-axis position control modules that can drive stepper motors or servo motors, and are widely used in various machinery, machine tools, robots, elevators and other occasions.

4. Data processing

PLC has the functions of mathematical operation, data transmission, data conversion, sorting, table lookup, bit operation, etc., and can complete data collection, analysis and processing. Data processing is generally used in all large-scale control systems in papermaking, metallurgy, and food industries.

5. Communication and networking

PLC communication includes communication between PLCs and communication between PLC and other intelligent devices. With the development of the factory automation network, the current PLC has a communication interface, and the communication is very convenient.

In fact, PLC has been widely used in various fields of industrial production. From the perspective of industry, metallurgy, machinery, chemical industry, light industry, food, building materials, etc., hardly use it. It is not only used in industrial production, but also in some non-industrial processes, such as building automation and elevator control. It is also used in the regulation of environmental parameters in agricultural greenhouses and in water conservancy irrigation.