【正文】 if not,it quits the interrupt. processing subprogram of send interrupts The processing subprogram of send interrupts is responsible to send data to the puter,sending interrupt state is off in the the munication program pletely deals with data with data sent by PC microputer,the symbol “1”can be written to send the puter receives the symbol ”1”,it is said that single chip puter executes pletely the introduction sent by PC the serial port interrupt is set as “off” state by the single chip microputer and it is set “on” state again after data are the single chip microputer returns to main program and waits for receiving instructions. DESIGN OF COMMUNICATION PROGRAM OF PC MICROCOMPUTER AND SINGLE CHIP MICROCOMPUTER In order to realize the system software easily grafted and uniformity,the program of upper puter is designed using the Boland C++ Builder as a programming tool in the control system ?s the Boland C++ Builder as a programming tool for PC serial port munication can be utilized in two ways:First,register ponents,C++ Builder does not in itself provide a separate serial munication ponent,but it can be obtained through registered Microsoft MSComm32 ponents,in which it is relatively simply for VB,VC in this second method is called Windows API(Application Program Interface)function,in which this function is provided by the operating system in order to provide a lot of executive program steps is followed: (1) Setting by munication protocol and opening the serial port,which is called initialization,then blocking the other program to use the serial port. (2) Configuring the serial port. (3) Transmitting data by the serial port to and fro,verifying data during transmission. (4) Closing the serial port as no needing it so that other program uses. The subinterface is simple,in which the setting on subinterface parameters are defaults,such as baud rate that single chip munication module has been set to 2400Bps and that the baud rate is set to 2400Bps in the puter setting on the PC microputer has two ports called as serial port COM1 and COM2 generally,so the program can automatically identify serial port so that it can send and receive data and instructions successfully. Serial munication program includes two aspects,one is MCS51 microcontroller munication program,on the other hand for the PC,the munication the preparation processes,the development of the two protocols is very important,otherwise it will not guarantee the reliability of data munications,and thus lose the meaning of munication protocol is agreed as follows: 1) The serial munication baud rate is 1200bps. 2) The frame format is:a start bit,eight data bits,a programmable ninth bit(this bit is sent and received address/data flag),one stop bit. 3) Set the address of the microcontroller code before sending the data in the address code,such as the address code is the correct transmission of data,or to contact the address code. 4) No munication of data accumulation and verification of the method,that is,each carrying one st of data (number of custom,is set to 100),a cumulative and whether the correct checksum,the right to send you back to the 00H,or loop back FFH. 5) Communication can interrupt transmission and are ways to search for in the munication. 6) PCcontact for the initiative to contract MCS51 microcontroller. 7) PC machine using COM2 munications. VI. CONCLUSION Th