IEC 61158-4-21:2019
工业通信网络 - 现场总线规范 - 第4-21部分:数据链路层协议规范 - 21类元素

Industrial communication networks - Fieldbus specifications - Part 4-21: Data-link layer protocol specification - Type 21 elements

被代替

标准号

IEC 61158-4-21:2019

发布

2019年

发布单位

国际电工委员会

替代标准

IEC 61158-4-21:2023

当前最新

IEC 61158-4-21:2023

 

 

适用范围

General The DLL provides basic time-critical data communications between devices in an automated environment. Type 21 provides priority-based cyclic and acyclic data communication using an internal collision-free@ full-duplex dual-port Ethernet switch technology. For wide application in various automation applications@ Type 21 does not restrict the cyclic/acyclic scheduling policy in the DLL. Specifications This document describes: a) procedures for the timely transfer of data and control information from one data link user entity to a peer user entity@ and among the data link entities forming the distributed data link service provider; b) procedures for giving communication opportunities based on ISO/IEC/IEEE 8802-3 MAC@ with provisions for nodes to be added or removed during normal operation; c) structure of the fieldbus data link protocol data units (DLPDUs) used for the transfer of data and control information by the protocol of this document@ and their representation as physical interface data units. Procedures The procedures are defined in terms of: a) the interactions between peer data link entities (DLEs) through the exchange of fieldbus DLPDUs; b) the interactions between a data link service (DLS) provider and a DLS-user in the same system through the exchange of DLS primitives; c) the interactions between a DLS-provider and a physical layer service provider in the same system through the exchange of Ph-service primitives. Applicability These procedures are applicable to instances of communication between systems that support time-critical communications services in the data link layer of the OSI or fieldbus reference models@ and that require the ability to interconnect in an open systems interconnection environment. Profiles provide a simple multi-attribute means of summarizing an implementation??s capabilities@ and thus its applicability to various time-deterministic communications needs. Conformance This document also specifies conformance requirements for systems implementing these procedures. This document does not contain tests to demonstrate compliance with such requirements.

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