The Research Of Developing FBD Platform And Conversion To Ladder

The ladder diagram and function block diagram are two kinds of graphicalprogramming languages used by programming logic controller.Much attention have beenattracted on FBD in both PLC and DCS system. FBD platform has not yet been developedin CASS system, and is needed to support. At present, the mutual transformation betweenIL and LD has been included in CASS system, how to convert the function blockdiagram to the IL instruction is an important part of the FBD to LD conversion.The main work of the paper is as follows:(1) According to international standards,design and develop the block function modules that in line with the IEC61131-3international standard.(2) A software platform environment for the function module groupis constructed.(3) Realize the conversion from block function diagram to instruction list.The main steps are as follows: use XML description tools to store the function module; mapthe function module to AOV node.(4) The sequence of two fork decomposition treeproducts IL instruction. The key technologies are:1) The XML according to PLCopen Part5is used to describe FBD to solve a series of problems such as exchange and standards;2)Use lines to show the series parallel relationship between function modules, change thelogical form of expression to facilitate post processing;3) propose the ranks of labelingalgorithm of function block in the control programs.At last, we used NC machine tool to verify the correctness of development platformand conversion algorithm. The experiment shows that the algorithm not only achieves theconversion to instruction list program, but also provides new ideas for the transformationfrom graphic language to text language.Its unique technology advantages will play an important role in the motion control andvisual control, therefore the development of a set of both traditional and has developmentand reconfigurable FBD is the focus of the present stage.