| With the continuous improvement of the automation of the industrial control systems,industrial control systems have put forward higher requirements on the field bus’ s transmission speed,real-time and compatibility.Meanwhile,the development of computer technology and network technology have made the field bus develop in the networked direction.Industrial Ethernet field bus is presented in such a context,and compared to traditional fieldbus,industrial Ethernet field bus has the advantages of fast transmission speed and good compatibility,and currently has been widely used in a variety of control systems.The common industrial Ethernet fieldbuses include SERCOS-III,PROFINET-IRT,Power Link and Ether CAT,among which Ether CAT has become a hot research field for its advantages in the fast transmission speed and good instantaneity.Ether CAT is an industrial Ethernet technology developed and designed by BECKHOFF,a German company.Ether CAT has been modified the parts in the standard Ethernet that are not suitable for the industrial control,applied the master-slave communication mechanism instead of the CSMA/CD mechanism and eliminated the uncertainty of data exchange.Ether CAT uses a cluster frame(that is,all nodes on the network share an Ethernet data frame)to improve the utilization of the message.At the same time Ether CAT also retains the advantages of Ethernet in the fast transmission speed,compatibility and low cost.In order to solve the communication problems between the PLC controller and field devices,this thesis had studied the Ether CAT Industrial Ethernet technology,designed Ether CAT master station applied for the PLC controller,which could complete the data communication with the field device designed in this thesis with good instantaneity.This thesis is based on the following steps in order to achieve the design of Ether CAT master station:First of all,the development status of industrial Ethernet was studied.By comparing several common industrial Ethernet,this thesis pointed out the advantages of Ether CAT,and studied the development status of Ether CAT at home and abroad,as well as the system composition,data frame structure and addressing mode of Ether CAT.Secondly,a new Ether CAT master program is proposed.This thesis analyzes the shortcomings of several common Ether CAT master stations,and presents a multi-core CPU-based Ether CAT master implementation plan in order to solve these shortcomings.And again,the Ether CAT master station proposed in this thesis has been designed in detail.The idea of stratification for the design of the software implementation plan has been used in order to improve the maintainability and portability of the master station.The Ether CAT master is divided into the Ether CAT protocol stack layer and the Ether CAT master service layer,and the realization of each part have been explained in detail.In the end,the Ether CAT master designed in this thesis is validated.The main functions and real-time performance of the Ether CAT master are tested with a simple but complete test program.The test results show that the Ether CAT master station designed in this thesis meets the requirements of PLC controller,with its performance indicators meeting the system requirements. |
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