Automatic connections in IEC 61131-3 Function Block Diagrams

IEC 61131-3 standard defines five languages for programming industrial controllers. They support both textual and graphical development approaches. In case of Function Block Diagram graphical language, diagrams consist of a set of elements connected with lines, which have various length and shape. Development of an editor supporting diagrams design involves implementation of an algorithm, which is able to automatically find a suitable connection between blocks. In the paper an appropriate application of A* algorithm is proposed. The authors have ensured that the proposed solution is efficient and work smoothly. Relations between implementation details and performance are discussed. Achieved results caused that the mechanism has been introduced into graphics editors available in CPDev engineering environment for programming controllers.