In this paper，the research of the principal and process of the data-sampling card which is based of AT89C52 is expatiated in detail．The text uses MAX197 as an A/D converter and the precision of the acquisition can reach 0.1%FS .The instrument has eight channels，it can selects an electrical signal in one certain channel via using SCM programming.The voltage sampling scope of each channel can be from 0V to 5V,and the speed can reach 100kSPS when collecting with only one channel.The use of 89C52 microprocessor is to design a small-scale data-acquisition system, which includes keyboard module, show module, A/D module, and communication module. The data is transmitted to computer by isolated RS-232 and RS-485 interface. Delphi 6.0 is used to workout the software to achieve the target of communicating between the PC and the chip.What is more,a show interface ,which have some functions such as instantaneous data sampling and dynamic sampling curve, is protract by the software.Besides,compilation language is used to program the chip,including data sampling program,incepting program and sending program. Finally we use Protel DXP to print samulink PCB board and adjust the speed, And debug the system ,analyzing and solving the problem which appears in the procedure in debugging .
