PLC is widely applied in all industrial departments in developed countries, which is include steel industry, petroleum industry, chemical industry, automobile industry, construction material industry, machine manufacturing industry, etc. with the development of all kinds technology, function of PLC improve dramatically, therefore application scope of PLC has enlarged continuously.
1. Logical Control of Switch Signal
This is the most important function. The design idea of PLC is logical control of switch signal. PLC substituting for control of relay can realize combinational logic control, timing control, sequence logical control. The logical control of switch signal is used on single machine, for example injection molding machine, printer, modular machine tool, grinding machine, etc. it also can be used on automatic production line.
2. Motion Control
Proper motion control module possessing function of simulating motion law precisely control position and speed which is widely applied in processing machinery, elevator and robot.
3. Analog Signal Processing Control
PLC can realize digital – analog conversion and analog – digital conversion by means I/O analog module, and finish PID closed loop control. The function is used in some situation, such as temperature, liquid flow.
4. Data Processing
The newly PLC possesses mathematical operation function such as, arithmetic operation of integer, matrix operation, function operation, logical operation of word, complementary operation, transmit data, then finish collecting data, analyzing data, processing data.
5. Network Communication
PLC can communicate with other PLC, remote I/O module, can communicate with several PLCs, it can constitute DCS with intelligent device.