Development of re-configurable distributed controllers in 61499 based on task schedules described by UML diagrams or Gantt charts

Achieving re-configurability and flexibility of the control software was one of the main factors that stimulated the emergence of the standard IEC 61499. The current paper is concerned with the re-configurability aspect in terms of control process within the scope of this standard as a task scheduling approach is presented as a probable solution. Task scheduling is proposed as a means of describing the process sequences of a sub-system in an effective and reconfigurable way. When orders of the processes need to be changed for a different mode of operation or even in case of total depreciation of the previous processing sequences, the changes can be actuated through task schedules. This allows re-configurability of the sub-system to be achieved during runtime without stalling the controlled operations. The task schedules can also be associated with a maximum time limit for particular task executions and this may help in monitoring the controlled hardware´s actions. For the description of the schedules timing and sequence diagram of UML as well as Gantt charts are investigated. The implementation of the proposed approach on a resource-restricted hardware imposes some additional design constraints.