The Implementation Of The Master Station Communication Driver Of EtherCTA Based On Distributed Clock Synchronization

The real-time industrial Ethernet fieldbus has advantages like efficient data transmission,big transmitting data,good real-time quality,safe and reliable communication and so on,which gradually replace traditional fieldbus to apply in the field of industrial field control.With the improving processing need of high speed and high accuracy of high-class numerical control devices,we design EtherCAT master station communication software based on distributed clock synchronous method which will improve the real-time communication function between master station and unofficial servo device and also improve entire system synchronous accuracy.On the base of communication mechanism of frame synchronization and distributed clock synchronization in EtherCAT periodic communication,we propose a communication method based on time axis accuracy which will improve the synchronization accuracy and the periodic communication effect of system.EtherCAT uses master-slave mode access method: the master station sends data frame to each slave station and slave station reads or writes data from the specific location of data frame.According to the study of EtherCAT industrial Ethernet data structure and type,addressing mode,frame process method,key technology and master station function,we will understand better for EtherCAT master station communication protocol architecture,DS401 protocol and DS402 protocol.We design the EtherCAT master station software based on distributed clock synchronous mode.We use Linux as our master station software platform and finish the state transition and system configuration of slave station from Init state,Pre-op state,Safeop to Op state.Finally,we design relevant experiments to test the accuracy,real time,system synchronization effect and other functions of data transmission of EtherCAT master station software.Our experiments show that EtherCAT sofeware communication function is good.