document: Schedulability analysis of real-time traffic in WorldFIP networks : an integrated approach The WorldFIP protocol is one of the profiles that constitute the European fieldbus standard EN-50170 . It is particularly well suited to be used in distributed computer-controlled systems where a set of process variables must be shared among network devices . To cope with the real-time requirements of such systems , the protocol provides communication services based on the exchange of periodic and aperiodic identified variables . The periodic exchanges have the highest priority and are executed at run time according to a cyclic schedule . Therefore , the respective schedulability can be determined at pre-run-time when building the schedule table . Concerning the aperiodic exchanges , the situation is different since their priority is lower and they are bandied according to a first-come-first-served policy . In this paper , a response-time-based schedulability analysis for the real-time traffic is presented . Such analysis considers both types of traffic in an integrated way , according to their priorities . Furthermore , a fixed-priorities-based policy is also used to schedule the periodic traffic . The proposed analysis represents an improvement relative to previous work and it can be evaluated online as part of a traffic online admission control . This feature is of particular importance when a planning scheduler is used , instead of the typical offline static scheduler , to allow online changes to the set of periodic process variables
doc_bio_tags: O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I
extractive_keyphrases: worldfip networks communication services aperiodic exchanges traffic online admission control periodic process variables
abstractive_keyphrases: en-50170 european fieldbus standard real-time traffic schedulability analysis distributed computer-controlled systems first-come-first-served policy real-time communication scheduling algorithms response time