Everyone who knows electronics knows that PLC is a very important device and a relatively difficult technology. It is a digital computing operation electronic system designed for industrial applications. It is industrial automation and Internet of Things. The basis of control, the future has a very broad application prospects.
PLC technology originated in the United States. The first application of PLC was American General Motors. In the 1960s, when they adjusted the factory production line, they found that the relay and contactor control system were difficult to modify, large in size, noisy, inconvenient to maintain and reliable. Poor sex. Subsequently, the US Digital Equipment Company developed the first programmable controller, which was effective in the trial of the General Motors production line. After that, PLC technology was carried forward in Japan and Europe. Japan, Germany and other successful development of programmable controllers. In 1974, China began to study programmable controllers and widely used in various fields.
PLC was the first to replace the mechanical switch device, and then the function of the PLC gradually replaced the relay control board. Modern PLC has more functions, and its use extends from single process control to control and monitoring of the entire manufacturing system.
At present, PLC technology is widely used in various industries such as industrial automation, automotive electronics, transportation, and Internet of Things control. Its role in these fields can be roughly divided into four categories.
application to achieve various motion control
The PLC controller is a digital electronic device with a microprocessor for automatic control of the digital logic controller. The control commands can be loaded and stored in the memory at any time. The programmable controller is composed of an internal CPU, instructions and data memory. Input and output units, power modules, digital analog and other units are modularized. The PLC controller can be used for the control of circular motion or linear motion. Today, the main PLC controller products have almost all motion control functions, which are used in various machines, machine tools, robots, elevators and other occasions.
From the control mechanism configuration, the early use of the switch I/O module to connect the position sensor and the actuator is now generally using a dedicated motion control module, such as single or multi-axis position control that can drive stepper motors or servo motors. Module.
To achieve industrial process control
As an industrial control computer, PLC controller can program a variety of control algorithm programs to complete closed-loop control. In industrial process control, PLC mainly performs closed-loop control on parameters such as temperature, pressure, flow and other analog quantities. Large and medium-sized PLCs have PID modules. PID adjustment is a much used adjustment method in general closed-loop control systems. Many small PLC controllers also have this function module.
To achieve related data processing
Modern PLC controllers have functions such as mathematical operations, data transfer conversion, etc., which can complete data acquisition, analysis and processing; these data can be compared with reference values stored in the memory to complete certain control operations, and can also be transmitted using communication functions. Go to other smart devices. In large control systems, such as unmanned flexible manufacturing systems, the PLC controller is one of the core components.
PLC communication and Internet of Things
With the trend of industrial Internet of Things, the related technologies of PLC communication and Internet of Things will be popular in the future. The usual PLC controller communication includes communication between the PLC controllers and communication between the PLC controller and other smart devices. With the development of industrial automation, all PLC controller manufacturers attach great importance to the communication functions of PLC controllers, and have launched their own network systems. The new PLC controllers have communication interfaces, and communication is very convenient.