WorldFIP现场总线设备功能块的应用开发

Development of Function Block Application of the Fieldbus Device Based on WorldFIP

旨在开发一个基于WorldFIP协议的现场总线智能仪表, 实现与上位组态软件直接的通信。现场总线智能设备中功能块的设计实现是实现智能设备现场控制功能的核心。功能块表达了功能块应用所实现的基本自动化功能。每一个功能块都要根据特定的控制算法和一套输入、输出和内部控制参数对输入信号进行处理。文中分析了WorldFIP总线现场设备中功能块的特点, 结合上位组态软件的设计思想, 阐述了现场总线仪表内存按参数类型和组态程序段来分区设计及实现方案: 在现场设备的内存中分配四大数据区, 分别为指令区、输入参数区、输出参数区及内含参数区。对应建立四大指针, 分别为指令区指针, 输入参数区指针, 输出参数区指针, 内含参数区指针,以方便程序的执行。同时建立程序段与仪表内存分配之间的一一对应关系。实验证明该方案科学合理。

The purpose of this study is to develop a fieldbus intellegent device based on WorldFIP, and to implement the communication with the configure software in the host computers. The design and construction of the function block in the Fieldbus intellegent device is the core to achieve the real-time location control function of intellegent devices. The function blocks have the basic automation functions required by its applications. Each function block must process the input signal according to a pre-determined control algorithm, a set of input/output and internal control parameters. This paper analyses the characteristics of the function blocks used in the devices based on the WorldFIP, and also presents a design method and its implementation scheme for the memory partition according to the types of parameters and the program segments in the configuration program in the Fieldbus devices. Using this method, four areas in the memory of a device are allocated for data, which are the command area, the input parameters area, the output parameters area and the contained parameters area, and four points are created accordingly for the ease of execution, which are the command area pointer , the input parameters area pointer, the output parameters area pointer and the contained parameters area pointer. At the same time, the mapping between the program segments and the memory areas allocated in the device is created . The experimental study shows that the design method and its implementation scheme are reasonable.