SIMATIC PLC is the Germany Siemens company launched in 1995, high performance–price ratio of the PLC system. Which micro-SIMATIC S7-200 series, 8DI/6DO is the minimum configuration, scalable 2~7 module, maximum I/O point numbers 64DI/DO, 12AI/4AO. Small and medium of SIMATIC S7-300, S7-400 series of high-end properties. PLC SIMATIC S7 series are modular, no exhaust fan and easier for users to control the structure characteristics and PLC S7 series of choice for a variety of applications from small scale to large scale product. The system provides complete control is convenient and economical solution. Among them, the S7-300 due to the excellent characteristics of the system in recent years, are widely used in special machine tools, textile machinery, packaging machinery, general mechanical engineering, control systems, machine tools, building automation, electrical appliance manufacturing industry and related industries, and many other areas. S7-300 provides a variety of performance increases CPU and rich I/O expansion module with many convenient features and various functional modules can be very good to meet and adapt to the automatic control tasks so that the user can choose suitable modules according to practical applications, and as you increase and more complex control tasks, additional modules to extend the PLC at any time, extend flexible. The contents of the paper focused on S7-300 PLC.
SIMATIC S7-300 functions to support and help the user programming, start-up and maintenance, the main function is as follows:
1. High-speed instruction processing
SIMATIC 0.1~0.6 μ s S7-300 instruction processing time, performance requirements for middle–to lower–range opens up new application areas. Floating point arithmetic functions can effectively achieve more complex arithmetic operations. Software with a standard user interface for parameter assignment tool is available to all modules.
2. Human-machine interface (HMI)
Convenient way of human-machine interface has been integrated in the S7-300 operating system, interactive programming requirements significantly reduced. SIMATIC human machine interface (HMI) obtained from S7-300 data S7-300 operating system automatically handles data transmission.
3. Diagnostic functions
Intelligent diagnosis system can continuously monitor the system‘s CPU for proper functionality, record error events and special systems (such as timeouts, module replacement).
4. Password protection
Multilevel password protection lets you effectively protect their technology secret, preventing unauthorised copying and modifying. Mode of operation selection switch can be pulled like keys, when the key pull out, you cannot change the mode of operation. This prevents illegal delete or overwrite the user program.