Design Of Valve Control System Base On PROFIBSUS Field Bus

Electronic valve is widely used to cut and isolate the medium in the industrial site. Valvecontrol equipment is the key of the valve control system. With the improvement of electronictechnology and application of field bus, valve control system developed with digital andintelligent characteristic. In this thesis, valve control equipment based on AVR is introduced,which can connect to the PROFIBUS network and establish an integral system.According to the practical requirement, the opening of the valve is selected as the controlvalue. The characteristics of the controlled object are analyzed by establishing the transferfunction of the actuator. The bang-bang control theory is selected to meet the requirement ofaccuracy and applicability.The valve control system introduced in this thesis includes the master station and theslave, the master is used to monitor the data remotely while the slave is used to collect thesignal and execution of the control action. Using Atmega-32as its control unit, the slave is thecontrol equipment in the industrial site, which can be divided into intelligent valve sensor,output relay module, input module for key and alarm signal, and field bus correspondingmodule. The magnetoelectric encoder is applied in the intelligent sensor to collect the signalof valve position, moreover Atmega-48is applied to process the data from the encoder andcommunicate with the main controller through SPI. In addition, the selection of componentswith low dissipation declines the power consumption of the whole equipment, which canwork well with the power supply of the battery. The temperature of the motor and the torqueof the shaft are monitoring by the equipment, which will send out alarm signal whennecessary. The user can view the information of valve position and set the parameter of thesystem through the keys and the LCD.The master station is consisted of a PC and a network card. The tasks of the masterstation design are the arrangement of the network and the design of the HMI interface. Thefunction of the master station is realized by the compiling of GSD file, the configuration withSTEP-7, and the interface design in WINCC. By the application of field bus bridge the task ofdata communication between the master station and the slave is accomplished, and the designof valve control system based on PROFIBUS-DP is completed. The result of the test of bothhardware and software shows that the system can work stably, accurately and efficiently,which meet the design requirement and is with guiding and practical value.