Time-Complemented Event-Driven Architecture for Distributed Automation Systems

Time-driven and event-driven control models are two fundamental design paradigms applied in distributed control systems for synchronizing decentralized activities. This paper proposes a unified architecture for combining both approaches. The combination offers the best of both worlds´ properties, such as the expressiveness of event-driven programming and the determinism of time-driven logic. The foundations of this symbiosis are the IEC 61499 Function Block standard providing event-driven distributed control architecture and the IEEE 1588 Precision Time Protocol establishing the basis for highly-accurate time synchronization. The proposed time-complemented event-driven distributed control model aims at improving the modularity and flexibility of automation software with satisfactory control performance. The new control model has been compared with conventional centralized and distributed control approaches analytically and by simulation. The comparison results reveal that the proposed control model is efficient and flexible. Finally, a reference example has been used to demonstrate merits of the new approach.