Determining the worst-case reaction time of IEC 61499 function blocks

Abstract

The IEC 61499 is an international standard for describing industrial process-control systems. Such systems typically consist of embedded computers that interact closely with physical processes within a feedback loop. In order to correctly control these physical processes, computations in response to inputs need to be done in a timely manner. A program's worstcase reaction time (WCRT) to inputs is usually used to ensure that timing constraints are met. Unfortunately, the standard has no provisions for specifying real-time constraints. Moreover, typical implementations of IEC 61499 are tightly coupled to their runtime environments-each with possibly different semantics and temporal properties-which makes it difficult to automate the estimation of their WCRTs. We propose to adopt a synchronous model for IEC 61499 programs. This allows the programs to be executed without the need of a run-time environment. Consequently, we are able to use a novel model-checking technique to estimate the WCRT of IEC 61499 programs. Experimental results on a suite of programs show that this approach provides conservative estimates that are, on average, less than 10 percent off from the actual WCRT.

Precise timing analysis for direct-mapped caches

“…We compare the precision and analysis time of the concrete, abstract, and proposed approaches over a set of benchmarks consisting of five control applications from [6]. In addition, we created two examples: a BubbleSort program and a Synthetic example.…”

Scalable and precise estimation and debugging of the worst-case execution time for analysis-friendly processors: a comeback of model checking

“…It has been demonstrated that model checkers are useful at computing the WCET of simple programs [32,37], but the scalability issue has not been addressed before. The idea is to take a program that is annotated with timing information, translate it into a model and use a model checker to verify the property "at program exit, execution time is always less than X", where X is a proposed WCET value.…”

TIC: a scalable model checking based approach to WCET estimation

“…Kim et al [16] experiment with computing WCET using Model Checking on small and simple programs. Kuo et al [18] use Model Checking for WCET computation for specific function blocks where program complexity is low. However, on benchmark WCET programs, Lv et al [20] show that model checkers face scalability issues on complex programs, whereas the ILP technique can compute WCET almost instantly.…”

“…It has been demonstrated that model checkers are useful at computing the WCET of simple programs [16,18]. The idea is to use a Model Checker as an oracle which, given a program (with timing information annotated) and a proposed value of its WCET, checks if there is an execution that takes longer than the proposed WCET.…”