Research On Wave-Height Acquisition System Based On EtherCAT

EtherCAT technology developed by Beckhoff Automation company of German is a real-time Industrial Ethernet which can directly access to I/O layer. It is the fastest Industrial Ethernet bus currently. With the development of data acquisition system, The traditional RS-485, USB and other means of communication can not meet the needs, Therefore, the data collection technology combined with real-time Ethernet is a new trend.According to the need for collecting wave height in The State Key Laboratory of costal and offshore engineering in Dalian University of Technology, a multi-channel data acquisition system based on EtherCAT is designed and developed,and PIC microcontroller is the microcontroller of it. The system uses master-slave structure.The master just installs one normal NIC not other special interface cards. EtherCAT slave controller uses three interface modes connecting with slave equipments.This design not only implements traditional data acquisition, but also applies to large amount of data and wide scope of data acquisition. And because the frame processing is completed by ET1100, it can applied to control areas with high speed.First, the paper briefly introduces EtherCAT protocol and communication theory, and discusses the makeup and the scheme of the data acquisition system. Then the hardware design is given, and the issue of selecting chip is referred. According to the scheme of system, the design theory of the system is described in models. The following is the part of software of data acquisition card, which includes master implementation and slave programs. The master implements the configuration of slave devices by TwinCAT of Beckhoff, and master data acquisition Interface is designed. The slave programs include network interface program and data acquisition control program.At last, the data acquisition system is tested by experiments, the analog waveform is collected and analyzed. The result of experiment shows that the system basically meets the requirements of the actual wave-height acquisition.