Soft PLC Research And Development System Based On PC

Abstract

With the development of industrial control technology, the drawbacks of traditional PLC gradually emerged. Although most of the PLC manufacturers have similar programming language, the PLC hardware and software products are not compatible. Also, their configuration, addressing and grammatical structure are inconsistent. Every PLC company uses their own program software which is quite expensive, less compatible and lots are needed to operate under DOS environment. This leads to inconvenience to users and also is not conducive to the PLC program transplant. With the development of control technology, the inconsistency has become increasingly prominent. PLC technology is a newly developed PC-based technology, which is in accordance with IEC61131-3 international programming standards and having good openness and cost-effective. Actually soft and traditional PLC operate base on same theory in terms of their functions, it can be divided into development system and operation system. Through the development of PLC editing system, it can be downloaded into the operating system for the control functions. Advantages of Soft PLC technology and its system Advantages of Soft PLC A. Open system architecture. Soft PLC has a wide range of I / 0 ports and a variety of field bus interface, which supports a variety of hardware. Users can choose the appropriate hardware based on their own requirements for the composition of soft PLC. B. Sufficient instruction and control module. The instructions of traditional PLC are fixed; however, the actual industrial control may need to further define their algorithms. Soft PLC supports a variety of control algorithms and also users can embed their own control algorithms. C. Enhanced data processing capabilities. Make full use of the PC resources, for example, greater capacity memory, high-speed CPU and other hardware. D. Strong network communication. Soft PLC not only connects to enterprise management information system, facilitating the integration of enterprises, but also monitors industrial facility operation, achieving data transmission and online monitoring, editing, simulation, debugging and other functions. E. Standardized editing language. Soft PLC technology is developed based on the IEC61131-3 standard, thus, it would be easier to master the standard language development. Although soft PLC has various advantages, this technique still has some problems needed to be solved. For instance, the reliability of the equipment that required to work in a worse industrial environment; the real-time control, the preferred operating system of soft PLC is Windows NT, however, it is not a hard real-time operating system. Traditional PLC is a hard real-time, and so, it can provide fast, deterministic and repeatable reaction. Soft PLC system architecture Comparison between soft and traditional PLC: The construction of traditional PLC is shown as the figure 1.