| Large charge granulation production line connects the monitoring computer to the core controller by industrial Ethernet. The core controller realizes control over actuator and signal collection according to the communication between actuator and signal collector. In accordance with the principle of electrical control, granulation production line can be divided into five parts, i.e. computer monitoring subsystem, motor control subsystem, detection subsystem, measuring subsystem and pneumatic subsystem.The PLC control objects of pneumatic subsystem are pneumatic valves of reaction tank and technological segment control for valves on/off operations. According to the project requirements, pneumatic subsystem control modes can be divided into single valve independent control, manual single segment control, automatic single segment control and automatic multiple segment control. The control state can be normal state or debug state. In normal state, the control modes can be automatic single segment control and automatic multiple segment control. In debug state, the control modes can be the four choices mentioned above. In manual single segment control mode, it needs manual operation to switch start/stop add material valve, add pure water valve, stir slurry, jacket hot water circulating and boiler lighting equipments. However, in automatic single segment control mode, it can be manually operates the equipments in a single control segment according to the technologic process.This project uses SIEMENS s7-300PLC based on the research and analysis. The pneumatic control PLC program is designed in three stages. Firstly, it realizes manual control function of pneumatic valves. Secondly, it realizes semi-automatic control function. Thirdly, it realizes fully automatic function. The PLC program is then debugged. The test results show the control of the technologic process and action logic is reliable and the function meets the technologic needs. |
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