tailieunhanh - Programmable Logic Controller plant through MMI Part 3

Tham khảo tài liệu 'programmable logic controller plant through mmi part 3', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Practice of Industrial Control Logic Programming using Library Components 19 2007 and 3 writing a program that searches through PLC code and libraries and extracts FB usage statistics. At the time of the study the studied companies used the same PLC program development tool see Section . The PLC code investigated was structured as different projects each representing the code that runs on one PLC. In many cases one PLC controls one manufacturing cell but in some cases two or more PLCs are used for one cell. Normally a cell is divided into several stations and a PLC often controls more than one station. For a fair comparison between the studied companies nine similar projects were chosen at each company two underbody projects three respot projects one side line project one framing project and two transportation projects. In the underbody cells robots weld bolt parts together to form the floor of a car. In the respot line the car floor or body are transported between the cells by a conveyor system and in each cell robots perform extra welding bolting to increase the strength and to add extra parts. In the side line cells the sides of the car are built. In the framing cells the car body is built by welding together the car floor with sides etc. In the transportation cells conveyors lifts etc. transport the car floor or body. The projects and the libraries were exported to text files. The developed program reads those files and detects all instances of each FB. It detects both FB instances that are used directly in the projects and FB instances that are used indirectly. FBs are considered to be used indirectly if they are used inside an FB which has instances directly used in a project or in turn is used indirectly. The program presents usage statistics of the FBs. All used FBs were also classified into nine different categories see Section 5. The program presents the number of instances and proportion of each category. 3. Control program development This section .