Research On Key Technologies In The Embedded Data Acquisition System

Data Acquisition System is the forefront of on-line monitoring and fault diagnosis system, so its working performance will have direct impact on the accuracy of diagnosis and prediction. To meet the requirements of modern fault diagnosis system for multi-channel scattered acquisition, upper computer for centralized control, high accurate AD conversion, network communication architecture, an Embedded Data Acquisition System has been designed. It combines embedded technology with modern data acquisition technology, using embedded controller AT91RM9200 as its microprocessor chips, adopting embedded Linux as its Operating System, selecting ADS8364 as its analog-digital conversion and applying a socket communication technology based on TCP/IP protocol for the data exchange. The content of this thesis is an important part in the embedded data acquisition system.The hardware platform of this Embedded Data Acquisition System is constituted of a dominated board, data acquisition boards, a power supply module, network switches and other modules. Both the dominated board and the data acquisition boards have their own CPU, so each board can act as a independent system. Those boards not only can perform their own functions, but also can communicate with each another through the Internet, having a loose and coupled structure.The main contents of the thesis are as fellows: 1) The present status of the research on Data Acquisition System inside and outside of our country is summed up, and the related concepts of the embedded technology are introduced, then the purpose and significance of this issue are indicated based on all above. 2) Connecting with the hardware platform of this Embedded Data Acquisition System, the memory structure, the prefix processing circuit and analog-digital conversion circuits of the data acquisition board are represented. 3) The embedded Linux and the facility management under it are introduced. The key data structure and fundamental function of Linux character device driver are established based on the analysis of the Linux character device driver development. The mechanism of Loadable Kernel Module of device driver is analyzed, and the detailed steps of the device driver design process are expatiated. Then the program of the ADS8364 driver is completed with the C program language. 4) In order to realize the data exchange between the data acquisition board and the dominated board, the streamed socket programming technique based on TCP/IP protocol is adopted. According to the basic programming process of the socket communication, taking the data acquisition board as Client and the dominated board as Server, the socket communication programs of both the client and the server are coded. In the end the data exchange between the data acquisition board and the dominated board is achieved.The result shows that ADS8364 on the data acquisition board operates normally and stably after the ADS8364 driver is compiled and loaded. As a part of the application program, the socket communication realizes the data exchange between the data acquisition board and the dominated board successfully.