RunSync: A Predictable Runtime for Precision Timed Automation Systems

Abstract

Many complex industrial control systems need to meet stringent timing requirements. Ensuring that implementations can meet these requirements can be a very difficult task. IEC 61499 is an emerging standard for modelling and implementing large distributed industrial control systems. However, there is currently no established approach for executing IEC 61499 code in a distributed time-predictable manner. In this paper, we present a novel time-predictable runtime called RunSync for executing IEC 61499 on the Precision Timed (PRET) architecture FlexPRET. PRET architectures are designed to guarantee timing repeatability while preserving performance. They are often designed as RISC architectures which utilize multiple hardware threads to remove pipeline hazards. Determining the allocation of tasks to the hardware threads is a key problem when utilizing such architectures. Hence, in this paper it is demonstrated that through RunSync it is possible to dynamically map IEC 61499 tasks to hardware threads during runtime, while preserving determinism and remaining amenable to timing analysis. Following that, quantitative results are presented, showing the minimal overheads of RunSync compared to implementations of the existing synchronous approach. RunSync is thus demonstrated to be more performant with large IEC 61499 networks, and when there are more hardware resources to be allocated.