Design And Realization Of Counting Data Acquisition System Within Multitask Operating System

The Data Acquisition System is an important part of Industral Computerized Tomography (ICT). How to guarantee the stability , reliability and communality of Data Acquisition System's performance has important significance in improvement of ICT whole fuction.After long period researching in ICT development and manufacture ,ICT research centre Chongqing University has abundant experience and national preponderance .This project is a part of CD400BX ICT. As an important part in ICT ,the whole ICT will be affected directly by system stability of Data Acquisition Subsystem performance.The original design program of Counting Data Acquisition System continue to use the train of thought within DOS Operating System , but the Multitask Operating System Windows are absolutely distinguished form DOS.Because the way of system Data transmittance are program inquiring , at the same time the acquisition and transmittance process cannot be interrupted .This data transmittance mode within Windows will be disturbed by other program's interruption and lost the requested data.So we have improved the original design of CD400BX ICT Data Acquisition System.We shift the data transmittance mode from program inquiring to hard interruption,and install FIFO cache in front of data channel,in order to guarantee the stability, reliability of data acquisiton and transmittance.This paper introduced the development and status quo of ICT ,and the principle of ICT scanning. Detailedly discuss the logical function of every part of CD400BX ICT. At first we test and verify the communality between original design and data acquisition system with FIFO cache; then we quantitatively analyze the performance of data acquisition system with FIFO cache, and the results are satisfied.In the design ,we make use of two EDA tools MAX+Plus II and Protel99.Because of the using of Complex Programmable Logical Device(CPLD), we can keep untuched the original hard circuit in design and realization of counting card,so it inherited the advantage of its predecessor.In order to quantitatively analyze the performance of data acquisition system with FIFO cache ,we introduced the queueing theory to build mathematic model to test its quality.