With the development of microelectronics technology such as large-scale and large-scale integrated circuits, PLC has developed from the first bit machine to the present microcomputer based on 16 bit and 32-bit microprocessor, and has realized multi-channel processing of multiprocessor. Nowadays, PLC technology has been very mature, not only the control function is enhanced, the power consumption and volume are reduced, the cost is reduced, the reliability is improved, the programming and fault detection are more flexible and convenient, but also with the development of remote i/o and communication network, data processing and image display, PLC has developed to the direction of continuous production process control, It has become a pillar of realizing industrial production automation. Programming software is used in Siemens series industrial control products, including SIMATIC S7, M7, C7 and PC based WinAC programming, monitoring and parameter setting, which is an important part of SIMATIC industrial software. With its large number of convenient functions, step 7 software can effectively improve the efficiency of all automatic tasks. Whether it is configuration hardware, communication, programming, testing, commissioning and maintenance, document preparation and archiving, or operation and diagnosis functions, the software is a milestone product in the field.

Step 7 has the following functions: hardware configuration and parameter setting, communication configuration, programming, testing, start-up and maintenance, file building, operation and diagnosis functions, etc. Step 7 has a lot of online help for all functions. Open or select an object with the mouse, and press F1 to get help on the object. In step 7, project is used to manage the hardware and software of an automated system. Step 7 uses SIMATIC manager to manage the project centrally, which can easily browse the data of SIMATIC S7, M7, C7 and WinAC. SIMATIC software tools needed to implement various functions of step 7 are integrated in step 7. The new SIMATIC automation platform covers everything needed to achieve automation today: programmable logic controllers with various performance, complete units including operator panels, PC based control, external control and monitoring solutions, and communication networks. As a comprehensive integrated solution, all of these functions can be realized through a single user interface. The obstacles between PLC and PC environment, process and production technology, and even between standard software and automation software. This will lead us straight to the subject. Because the foundation of all these advantages is software. The software system is based on various versions of step 7: for users who use only a part of SIMATIC automation platform as hardware (and therefore do not need a full performance range), and for users who need to use the full performance range.