METHOD AND DEVICE FOR RETRIEVING A REACTIVE BEHAVIOR OF A PLC PROGRAM, AND METHOD AND DEVICE FOR DEBUGGING A PLC PROGRAM

摘要

The programmable logic control (PLC) program has a number N of tasks (N ≥ 1 ). The respective task has a number of execution paths, each one of the execution paths being individually executable in one cycle. For at least a plurality of cycles while executing the PLC program and for at least one task, the execution path of the respective task being executed in the respective cycle is recorded. Further, the reactive behavior of the executed PLC program is determined in dependence on the recorded execution paths of the at least one task. Then, a state model may be used to represent the reactive behaviour of a task program, wherein the respective execution path represents a particular state of the finite state machine, and a change from one execution path to another execution path represents a state transition of the finite state machine. Further, the finite state machine may be embodied as a Markov model, where the transition probabilities represent the observed relative frequencies of the changes from one execution path to another execution path in the original program run and the transition probabilities of the Markov model are used as indicators for identifying and localizing potential defects in the program run of the PLC program.