Since the industrial computer included in the national series of computer-spectrum and development planning, in the country's strong support of China's IPC was the cause of the rapid development in industrial control of development and industrialization of its application has been made substantial progress. In recent years, computer, communications, consumer electronics integration trend has become increasingly obvious, PLC technology has become a hotspot. PLC electrical system in the communications, electronics, automation and other fields have immense advantages, in fact, when handling capacity of more and more attention to research on the PLC operating system is continually deepening. As PLC technology has many advantages and good prospects for development, more and more manufacturers and application developers using PLC technology application development programmes. Currently, the country's shrinking machine electrical control system is widely adopted in the traditional relay - access control methods. Because of the need to control the electrical circuit more so than the complex, day-to-day production operations, frequent electrical failures, thus affecting production. In addition, a number of complex control such as: time, count controlling relay - contactor control more difficult to achieve, so it is necessary for traditional electric control system to improve the design. PLC electrical control system can effectively compensate for the shortcomings of this system.
