tailieunhanh - Programmable Logic Controller plant through MMI Part 6

Tham khảo tài liệu 'programmable logic controller plant through mmi part 6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 58 Programmable Logic Controller Station 5 links the production and expedition zones acting as or intermediate storage area of 16 positions. The different pieces cylinders are dispatched depending on the production orders and the storage policy of station 5. The original control system of the cell consisted of a programmable logic controller PLC that controlled each station. A real-time industrial net connected all of the PLCs. We then installed a new control system based on a fieldbus. The fieldbus was installed at stations 1 2 3 and 4 and at Transport 1 see Fig. 5 . Stations 1 and 4 have Inline modules Phoenix_Contact 2006 and stations 2 3 and Transport 1 have Advantys STB modules Schneider_Electric. 2006 . Fig. 5. Fieldbus and Product Identifier Both Transport 1 and Transport 2 identify the contents of every pallet by means of the read and write heads of the memories attached to the pallets. At the beginning of an operation at a cell station to determine the operation that has to be performed the memory of the pallet that arrives must be read. At the end of the manufacturing operation the memory of the pallet must be updated. The product identifier module is a resource shared by all of the stations. Communication with the identifier module is achieved using a serial port inserted in the Inline module of Station 1. Access to the module must be protected from concurrent access. 5. The input output module Communication with the control system could be established with the coordinators directly accessing the communications network to read or write each time that they need to interact 59 The Java based Programmable Logic Controller. New Techniques in Control and Supervision of a Flexible Manufacturing Cell. with the cell. This strategy would not be very efficient because even writing or reading only one station variable would involve a complete reading or writing of the bus. This task has therefore been left to the communications layer. The coordinators access the .