The Study On Data Acquisition System Based On EtherCAT Network

In the ocean engineering model experiment, various measuring instruments request transmitting real-time data to meet the requirements of the experimental data collection. Based on the existing data acquisition technology, the discrete measuring instruments are connected and a data acquisition system based on EtherCAT network is built in the paper.The data acquisition system based on EtherCAT employs the hierarchical architecture and the entire data acquisition system is composed of the monitoring layer, the communication layer and the device layer. The monitoring layer which consists of a PC with a standard network card achieves the management of the entire system and the data processing. The communication layer plays a connecting role in whole system; firstly, it carries out the real-time communication between PC and the EtherCAT slave, and then gets the data from the device layer through the corresponding interface. The sensor and detection equipments of the device layer which contact the real physical environment to complete the real-time measurement of various parameters such as the wave height, flow rate, pressure, six degrees of freedom motion parameters and power. Then the measurement results will be uploaded to the communication layer.The EtherCAT communication principles and the architecture of the EtherCAT network are firstly presented in the paper and then the overall design of the network data acquisition system and the respective solutions of different layers are proposed. Besides, the hardware circuit design of the slave station, the program design of logic controller (STM32and FPGA), the applications of the master control system and the communication program of the EtherCAT master are introduced in detail in the paper. Finally the entire network of the data collection system is built and the communication performance of the EtherCAT bus, the performance of the slave station and the system synchronization are tested, respectively. The results show the design of the data acquisition based on EtherCAT meets the requirements and achieve satisfactory result.