| Industrial control system design is moving towards Object Oriented approaches. These approaches use an event-triggered communication model where communication is triggered by the occurrence of a significant event. Traditional low-level control systems for safety-critical applications use a different approach, namely time-triggered. Following the OO trend, the new IEC 61499 Function Block standard outlines a design model that is event-triggered. This thesis proposes an event-triggered communication Escalating Priority (EP) scheduling technique that can handle both event and time-triggered communications.;In conclusion future challenges are identified that include the limitations of existing hardware, ambiguities in the IEC 61499 standard, and the potential for emerging industrial grade Ethernet technologies.;Worst-case performance analysis proves that EP scheduling technique has a deterministically bounded delay time equal to one cycle of messages (i.e. the total time for each node to send one message each). The game theory analysis shows the inherent fairness and responsiveness of the EP scheduling technique by a side-by-side comparison of payoff values. Finally, the discrete event simulation model confirms the deterministic maximum delay time, fairness between nodes and the EP scheduling technique's ability to schedule both event and time-triggered messages with varying message lengths even under a babbling idiot failure scenario. |
