| With the technology improvement of feed production, the DCS system which is based on computer and composed of the control, management, decision-making as one plays an increasingly important role in the feed production. Based on practical engineering background, this article researches into a new design of automatic control system for the feed processing line. The new system will not only integrate the industrial computer system and PLC system, but also in some parts use the FCS, and is a new type of distributed control system.The article proposes the corresponding control project according to the technique requirement of feed product line, and elaborates on the designing of the system structure and the software. The system, which selects the PLC of SIEMENS S7-300 series and the configuration software of WinCC 6.0 and constructs a distributed PLC control system using the PROFIBUS-DP Fieldbus Protocol, achieves the specialty of full digital, full distributed and full open, making more extension more extension of the function of the traditional Distributed Control System.Focus on the design of the hardware analysis of the electrical field device layer design principle, on-site control of the construction and design of communication networks. In PLC software design aspect, the readability becomes poor for some reasons, such as the diversity of blending technics,the complexity of the control and the emphasis on logic design of PLC programming, which troubles system maintenance and function expansion in future. Therefore, this article from modular object-oriented programming ideas, the use of the industrialization of the design method of functional modules, both for the convenience of large-scale PLC collective collaborative development process, but also allows easy additions and deletions and maintenance procedures, but also shorten the process development cycle. WinCC configuration software in the system design, covering the entire process of feed-processing analysis, and system communication configuration, the configuration GUI, configuration and management variables, the overall situation script program design etc. This article also applies PID algorithm of the classics control theory, and it has realized direct automatic frequency conversion control of grinder.This system has been proved interface friendly and stability as prospective. The system can apply not only in the feed processing industry, but also in metallurgy,chemical engineering,food,cement, medicine industry and etc. |
