The Implementation Of EtherCAT Fieldbus Interface In CNC System

As NC systems'demands for control accuracy and real-time is higher and higher, traditional analog interface can no longer meet the requirements of the development of modern NC technology. Ethernet is widely applied with low cost and high communication speed, and is rich in both software and hardware resources, so it can accomplish the seamless integration of office automation and industrial control network. Besides its sustainable development potential is great. For the above advantages, Ethernet is the inevitable trend of development of control network industry. The aim of the thesis is to combine industrial ethernet EtherCAT technology with arm embedded technology to meet NC systems'demands for high speed and high precision in controlling.At first, the development situation of NC technology and bus technology is introduced, and the EtherCAT technology protocol and its communication mechanism is researched, then the advantages are analyzed when EtherCAT bus is applied in NC system.Secondly,A proposal which adopts"embedded x86 industrial personal computer + EtherCAT master protocol card"to implement the master system is put forward, and EtherCAT master protocol card makes data interactive with embedded x86 industrial personal computer via PCI bus. The advantage of this proposal is that CNC software does not need to cope with EtherCAT about communication and distribution clock.This not only can solve the real-time problem of system, but also would reduce the burden of IPC core processor.Thirdly,the modules' hardware circuit and digital logic design of EtherCAT master card are stated in detail.The modules contain power module, data interchange module based on FPGA and EtherCAT protocol processing module. FPGA implements PCI interface, DPRAM and SPI interface; and EtherCAT communication is achieved by EtherCAT protocol processing module.Then,some softwares of EtherCAT master system are designed in this thesis,including master card control programs and cure protocol programs.Access of NC system upper application to DPRAM are achieved in master card programs,and periodic and non-periodic communication function and clock distribution function of EtherCAT are realized in cure protocol programs.At last, the thesis build up test platform with the EtherCAT master designed above and slave servo driver AX5206 from BECKHOFF to verify the feasibility of EtherCAT master's software and hardware and the validation of all functions.