Design And Implementation Of Bus-based Data Acquisition System

With the rapid development of science technology and electronic technology,in the field of aerospace and industrial production,large devices with complex structures and powerful functions are widely used,which has also brought harsh production environments.To ensure the smooth run of large equipments and staff's security,an real-time monitoring and measurement system has become an essential part,data collection has played a vital role in this system.Data acquisition system is an important bridge for communications between a computer and the external physical world.Currently,more stringent requirements for data acquisition systems in all areas such as the scope expansion,the accuracy increase,more channels of data collection and faster and more stable data transmission,in order to meet these requests,bus-based data acquisition system is designed.The data acquisition system is designed based on FPGA and RS-485 bus,and includes a master node and 32 slave nodes.The master node hangs 32 slave nodes through a bus,thereby collects data from 32 locations,and each location can collect 12 channels' analog signals with voltage values from 0 to 5V,then collected data transmits back to the master node by bus with the 20 Mbps rate.The data collection module of this system chooses a 24-bit delta-sigma(??)analog-to-digital converter ADS1258,the RS-485 bus-driver chooses a chip ISO1176 T with higher rates and more nodes,W5300 Ethernet network port is used to communicate with the PC.This paper first analyzes and makes the system overall designed scheme and the selection of main circuit modules' chips,and describes the design method of every part's hardware circuits in detail,while briefly introduces the core chips of each circuit module,then describes the system software's designed process and makes system communications agreements.At last,the main hardware circuits and the whole system are tested repeatedly,and the analog signals' calibration and test data is explained in detail.Test results show that the bus-based data acquisition system of the design has manycharacteristics such as a small volume,high bus transmission speed,high acquisition precision,reliableconversion data,stable work system and so on,can meet the all required indicators of this design.