The Research & Implementation Of Real Time Data Acquisition System Based On RTAI

Real time control and data acquisition system is a important portion in computer application. Real time operation system is the kernel of it. As long as the development of hardware, real time applications not only account for operation system more capability and more function. For example some of function of graphic interface, network. In the existing real time operations some one is too dearly, some one's function is too simple, some one lack of standard so that the interfaces is not compactable. In this case, chose an open standard compactable real time operation is importance for developing a real time control and data acquisition system.Base on this intent, this dissertation first mainly focuses on the elements of real time operation and analyses the relative concept that include task, task schedule, time of interrupt delay, interrupt response time, time of context reversion. Conclude the stuffs affect the capability of real time system. Then the dissertation introduce RTAI (Linux real time extent) and use it for data acquisition system's operation system. By comparing the difference of interrupt relay time between Linux and RTAI in the test, conclude that RTAI satisfy the request of data acquisition system.RTAI has no unified manage interface for hardware. The developer has to develop the device driver of its hardware. In order to solve this problem that make the development easily going, I adopt Comedi( Linux device driver control manage interface). It is compatible for Linux and RTAI. As the module of device managing, it provides a unified hardware manage interface. The developers can easily download the device driver from Comedi org and modify their own device driver in Comedi mode and submit it to the Comedi org. So it will decrease the work of development.Qt is a good graphic development tool for industry PC. PC has enough memory than some develop board, so choose Qt for graphic develop tool because of it is power than the Minigui.At the same time the dissertation introduce how to use TLC5510 COMS chip develop a real time data acquisition system. First the Comedi mode device driver collect the data by parport (EPP mode), then device driver send the data to the real time user process, and then the process share memory to the graphic process which is a Linux process(no real time). When the counter is out, the graphic process gets data from share memory and display.