Adding Local Priority-Based Dispatching Mechanisms to P-Net Networks: A Fixed Priority Approach
E. Tovar, F. Vasques and A. Burns
In this paper we address the real-time capabilities of P-NET, which is a multi-master fieldbus standard based on a virtual token passing scheme. We show how P-NET's medium access control (MAC) protocol is able to guarantee a bounded access time to message requests. We then propose a model for implementing fixed priority-based dispatching mechanisms at each master's application level. In this way, we diminish the impact of the first-come-first-served (FCFS) policy that P-NET uses at the data link layer. The proposed model raises several issues well known within the real-time systems community: message release jitter; pre-run-time schedulability analysis in non pre-emptive contexts; non-independence of tasks at the application level. We identify these issues in the proposed model and show how results available can be adapted to encompass priority-based message dispatching in P-NET networks.
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BibTex Entry
@inproceedings{Tovar2000,
address = {York, England},
author = {E. Tovar and F. Vasques and A. Burns},
booktitle = {Proceedings of the 11th Euromicro Conference on Real-Time Systems},
category = {scheduling},
pages = {175 - 184},
publisher = {IEEE Society Press},
title = {Adding Local Priority-Based Dispatching Mechanisms to P-Net Networks: A Fixed Priority Approach},
year = {2000}
}