Industrial Fieldbus System Design

Aiming at the shortage of the present industry control system, a control system using CAN bus adapter based on USB bus is presented. This system has high-speed smart communication ability with low power design, and it can be widely used in industrial control system .Firstly, by analyzing the evolution of control system, this paper introduces a variety of fieldbuses and the interface of industrial control computer. In the system, CAN bus is used as fieldbus which communicate with industrial control computer through USB bus.Secondly, the control system centering CAN bus and USB buse is realized. The CAN communication adapter base on USB bus, the network model and communication protocol of CAN bus are explained briefly. In the design of the hardwares, USB control chip PDIUSBD12 and CAN control chip SJA1000 from PHILIPS are used, P89C51 microchip from PHILIPS is the control chip, and the circuit of photoelectric isolation enhances the ability of anti-jamming. Using WinDriver, the Windows device driver of the adapter is developed. WinDriver can reduce the time of develop and improve the effect of develop.Finally, many essential parameters were tested, which include communication speed, the percentage of error, and the response time etc. All prove that the system has very good performance and great value in application. The system can communicate at500kbps with 100 device in 100m, and the response time is less than 0.5ms, the percentage of error is less than 1‰. So the system has the great value in industrial control system.