The Study On Simulation System Of Serial Bus Port

With the development of the technology of PC serial port communication, many companies use RS232 of the PC to connect with other equipments to communicate with or control them. In practical use, for not to influence the progress, companies always have to develop the equipment before bring in new equipments or components, it's hard to realize communication without hardware support, so we need a simulation system of serial port communication to emulate new equipments or components, the emulational system can simulation the communication status to connect and debug with exploitive equipment or component; another problem is that when two equipments or components fail to serial communication and can not decide which is wrong, debug simulation system can test each equipment or component and find the problem and solve it. So it has an important meaning of the serial simulation communication system to test and debug the communication of these equipments.There are two main parts of the article:One is the design of RS485 serial communication testing software in the use of Visual Basic 6.0 in the environment of Windows system. It contains both MODBUS communication and common communication, and the MODBUS communication is important in the software design. The software contains of host frame and subordinate frame, and this can satisfy the practical use. The task of the host frame is sending data and then receiving data from subordinate frame and judging the data is right or wrong; the task of the subordinate frame is receiving the data sending by host frame and then sending correspondence data based on receiving data. The software is mainly used in testing the communication of equipments.Another design is called SPI simulation system of serial port communication, this part is hardware design. The design makes full use of the characters of the pins of serial port to simulate the four lines of the SPI communication, and then connecting them with AD,DA converter or some other hardware that supporting SPI serial port. At the same time, the article takes 10-bit AD converter TLC1549 and 12-bit AD converter TLC2543 for example to describe hardware designs in detail, and designs the correspond software of TLC1549 in the use of VB. The ideas of the design are mainly used in testing the communication of components and also have important meanings in teaching.After the design of RS485 serial communication testing software, the article ues a temperature-control apparatus of a company that supporting MODBUS communication protocol and with RS232-485 converter to make some tests, the result is the software can finish the communication successfully.