Combined sequential and function-oriented programming for real-time systems

Usually, there are two alternative approaches to program the application functions to be performed by a hard real-time system: the method of sequential programming of tasks often performed under control of a multi-tasking operating system and, on the other hand, the quasi-parallel description of application functions which are realized by means of a cyclic execution e.g. of a programmable logic control. Although being alternatives in a wide area of applications, there are always aspects of each form of programming where the solution for a specific problem is not really satisfying. Therefore we tried to make use of a combined programming of real-time applications by means of both methods which showed to offer an optimal programming toolset. This paper presents specific characteristics of the two methods, aspects of the combination and examples coming from a new robot programming language which is designed this way.