Research And Implementation Of EtherCAT Communication Protocol

As NC system’s demands for real-time performance and control accuracy isincreasingly higher, the key to develop the numerical control technology lies on theresearching and applying of the high speed fieldbus. EtherCAT, a kind of industrialEthernet fieldbus which has been processing higher and higher market share, has verygreat potential. The aim of the thesis is to realize EtherCAT communication protocol byusing ARM and FPGA technology and bring it into the NC system. The main contents ofthe thesis are as follows.The development situation of fieldbus technology is first analyzed. The EtherCATcommunication specification and the gordian techniques needed to implement the fieldbusare set forth, containing the―in the fly‖technology, the synchronization technology ofdistributed clock as well as WKC and CRC checksum technology.The hardware proposal is put forward using embedded IPC and EtherCAT mastercommunication card to realize the hardware interface of the master system communicationand a friendly HMI is provided to display the status data and make it convenient for theapplication data to be input. The industrial personal computer communicates withEtherCAT master card via PCI interface. A hardware proposal which adopts―ARM+FPGA‖to realize the hardware interface of the slave is put forward, including the physicallayer, data link layer and application layer, among which ARM is used to achieve the slavefieldbus protocol driver while the FPGA is used to realize the fieldbus itself.The software of the EtherCAT master and slave is elaborated in the thesis. The masterprotocol is designed, containing the data transmission protocol as well as the highprecision distributed clock technology. Then the slave protocol is designed, containing thedata transmission protocol of the data link layer and the slave protocol driver.At last, the experiment platform of EtherCAT is built up and the PCI driver andprotocol driver program are designed. Through the experiment platform EtherCAT datatransmission function, real-time performance, synchronism and reliability have beenexamined and analyzed, which verifies the feasibility of the designed EtherCAT hardwareand software.