Designing Real-Time Systems Based on Mono-Master Profibus-DP Networks 1

Abstract

Abstract:Profibus networks are widely used as the communication infrastructure for supporting distributed computer-controlled applications. Most of the times, these applications impose strict real-time requirements. Profibus-DP has gradually become the preferred Profibus application profile. It is usually implemented as a mono-master Profibus network, and is optimised for speed and efficiency. The aim of this paper is to analyse the real-time behaviour of this class of Profibus networks. Importantly, we develop a new methodology for evaluating the worst-case message response time in systems where high-priority and cyclic low-priority Profibus traffic coexist. The proposed analysis constitutes a powerful tool to guarantee prior to runtime the real-time behaviour of a distributed computer-controlled system based on a Profibus network, where the real-time traffic is supported either by high-priority or by cyclic poll Profibus messages. Porto, Portugal, E-mail: vasques@fe.up.pt Abstract: Profibus networks are widely used as the communication infrastructure for supporting distributed computer-controlled applications. Most of the times, these applications impose strict real-time requirements. Profibus-DP has gradually become the preferred Profibus application profile. It is usually implemented as a mono-master Profibus network, and is optimised for speed and efficiency. The aim of this paper is to analyse the real-time behaviour of this class of Profibus networks. Importantly, we develop a new methodology for evaluating the worst-case message response time in systems where high-priority and cyclic low-priority Profibus traffic coexist. The proposed analysis constitutes a powerful tool to guarantee prior to runtime the real-time behaviour of a distributed computer-controlled system based on a Profibus network, where the realtime traffic is supported either by high-priority or by cyclic poll Profibus messages.

Building an interconnection between PROFIBUS and ATM networks

“…In the designed system, the maximum token rotation time is 24 ms that happens with the 1373-message cycle. This value is acceptable depending upon previous studies performed by Monforte and Alves (2000) and Tovar and Vasques, 1999a, b).…”

Engineering PROFIBUS networks with heterogeneous transmission media

“…There is the need to compute and set a number of relevant network parameters in order to guarantee bounded message response times, among other system requirements (e.g. [5][6][7][8][9]). …”

“…Ref. [17] analyses the PROFIBUS Standard's guidelines for segmentation and proposes a ''bridge-like'' behaviour.…”

Multi-Master Profibus Dp Modelling and Worst Case Analysis-Based Evaluation

“…They are defined as the maximum admissible time interval between the instant when the message request is placed in the outgoing queue and the instant when the related response is completely received at the master's incoming queue. In the paper, it will be assumed that Dh (Monforte, et al, 2000). Further, we assume that nh k and nl k are the number of high priority and cyclic low priority message streams, respectively.…”

“…Overcoming these limitations allows obtaining a worst-case response time analysis less pessimistic than that presented in (Tovar and Vasques, 1999), able to take into account more realistic information flow scenarios. In (Monforte, et al, 2000) some of these limitations have been overcome, but the analysis presented considered only mono-master Profibus communication systems. In this paper the analysis is extended to the more general multi-master scenario.…”