PAC Design Based On Embedded Linux

For many years, programmable logic controllers (PLC) have provided OEMs and end users with a highly reliable method of control. But traditional PLCs have some common problems, such as slow technology renewing speed, narrow system opening, and high price. With the arriving of PC and the Internet time, they set a higher request to PLC. In recent years, with the development of various new technologies, especially the soft PLC technology and built-in computer technology, massive new PLCs with PC controller, PC-BASED controller and the functional expansion appear. They have wider opening system and application scope, adopt distributional modular structure and can be integrated with many kinds of software technology that form the automatic control solution. So they are considered as the new generation of automatic control product—programmable automation controller (PAC).PAC is a new concept concerning automatic controlling product raised by Craig Resnick, ARC Advisory Group Director in 2002 compared with the relatively traditional PLC Control. PAC is actually a systematic concept, which can be divided into two parts- integrated software platform and hardware platform based on open modular structure. This paper designs a Linux-based embedded controller based on the definition of PAC. CPU of this controller adopts the ARM9 CPU architecture S3C2410, and operating system is the embedded Linux which is popular now. Controller integrates Ethernet interface and multiple serial bus interfaces, development language accords with IEC61131-3 standards, and the overall design accords with PAC open design standards.The first chapter outlines the PAC origin and characteristics. The second chapter describes the embedded Linux operating system and the ARM processor. The third chapter is the most important of this paper, which focuses on the PAC system hardware design and the specific method. The fourth chapter describes how to transplant Embedded Linux operating system to the hardware system. In the fifth chapter, we design a remote data acquisition card adopting RS485 communication technology. Chapter six introduces the PAC software system, and gives specific method. In chapter seven, we design a simple experimental procedure and a hardware driving program to test the entire hardware system. The result shows our proposed design is feasible.