Abstract: This paper presents a method of reading the signals of the proximity switch through the parallel communication of the computer under the environment of Windows XP,gives the design of the interface circuit,and then by using Visual C++ develops the program through the third software.This method has been applied in the implement of image acquisition system,and it shows that the design of the method is easy,highly stable and of low-cost.

Key words: parallel communication； proximity switch； photoelectric isolation；