SIST EN 61158-4-20:2015
(Main)Industrial communication networks - Fieldbus specifications - Part 4-20: Data-link layer protocol specification - Type 20 elements (IEC 61158-4-20:2014)
Industrial communication networks - Fieldbus specifications - Part 4-20: Data-link layer protocol specification - Type 20 elements (IEC 61158-4-20:2014)
IEC 61158-4-20:2014 specifies 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 and the structure of the fieldbus DLPDUs used for the transfer of data and control information by the protocol of this standard, and their representation as physical interface data units.
Industrielle Kommunikationsnetze - Feldbusse - Teil 4-20: Protokollspezifikation des Data Link Layer (Sicherungsschicht) - Typ 20-Elemente (IEC 61158-4-20:2014)
Réseaux de communication industriels - Spécifications des bus de terrain - Partie 4-20: Spécification du protocole de la couche liaison de données - Éléments de type 20 (CEI 61158-4-20:2014)
L'IEC 61158-4-20:2014 spécifie les procédures pour le transfert en temps utile de données et d'informations de commande d'une entité d'utilisateur de liaison de données vers une entité d'utilisateur homologue, et parmi les entités de liaison de données formant le fournisseur de service de liaison de données distribué et la structure des DLPDU du bus de terrain utilisée pour le transfert de données et d'informations de commande par le protocole de la présente norme, et leur représentation comme unités de données d'interface physique.
Industrijska komunikacijska omrežja - Specifikacije za procesna vodila - 4-20. del: Specifikacija protokola na ravni podatkovnih povezav - Elementi tipa 20 (IEC 61158-4-20:2014)
IEC 61158-4-20:2014 določa postopke za pravočasni prenos podatkov in informacij o nadzoru od enega uporabniškega osebka podatkovne povezave do uporabniškega osebka vrstnika in med osebki podatkovne povezave, ki tvorijo ponudnika storitev porazdeljenih podatkovnih povezav, ter strukturo DLPDU-jev za procesna vodila, ki se uporabljajo za prenos podatkov in informacij o nadzoru s protokolom tega standarda, in njihovo zastopanost kot fizični vmesnik podatkovnih enot.
General Information
Relations
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Industrijska komunikacijska omrežja - Specifikacije za procesna vodila - 4-20. del:
Specifikacija protokola na ravni podatkovnih povezav - Elementi tipa 20 (IEC 61158-4-20:2014)Industrielle Kommunikationsnetze - Feldbusse - Teil 4-20: Protokollspezifikation des Data Link Layer (Sicherungsschicht) - Typ 20-Elemente
(IEC 61158-4-20:2014)Réseaux de communication industriels - Spécifications des bus de terrain - Partie 4-20: Spécification du protocole de la couche liaison de données - Éléments de type 20
(CEI 61158-4-20:2014)Industrial communication networks - Fieldbus specifications - Part 4-20: Data-link layer protocol specification - Type 20 elements
(IEC 61158-4-20:2014)35.110OmreževanjeNetworking35.100.20Podatkovni povezovalni slojData link layer25.040.40Merjenje in krmiljenje industrijskih postopkovIndustrial process measurement and controlICS:Ta slovenski standard je istoveten z:EN 61158-4-20:2014SIST EN 61158-4-20:2015en,fr,de01-marec-2015SIST EN 61158-4-20:2015SLOVENSKI
STANDARD
SIST EN 61158-4-20:2015
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 61158-4-20
October 2014 ICS 25.040.40; 35.100.20; 35.110
English Version
Industrial communication networks - Fieldbus specifications - Part 4-20: Data-link layer protocol specification - Type 20 elements (IEC 61158-4-20:2014)
Réseaux de communication industriels - Spécifications des bus de terrain - Partie 4-20: Spécification du protocole de la couche liaison de données - Éléments de type 20 (CEI 61158-4-20:2014)
Industrielle Kommunikationsnetze - Feldbusse - Teil 4-20: Protokollspezifikation des Data Link Layer (Sicherungsschicht) - Typ 20-Elemente (IEC 61158-4-20:2014) This European Standard was approved by CENELEC on 2014-09-19. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions. CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique Europäisches Komitee für Elektrotechnische Normung CEN-CENELEC Management Centre: Avenue Marnix 17,
B-1000 Brussels © 2014 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN 61158-4-20:2014 E SIST EN 61158-4-20:2015
EN 61158-4-20:2014 - 2 -
Foreword The text of document 65C/762/FDIS, future edition 1 of IEC 61158-4-20, prepared by SC 65C “Industrial networks” of IEC/TC 65 “Industrial-process measurement, control and automation" was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as EN 61158-4-20:2014.
The following dates are fixed: • latest date by which the document has to be implemented at national level by publication of an identical national standard or by endorsement (dop) 2015-06-19 • latest date by which the national standards conflicting with the document have to be withdrawn (dow) 2017-09-19
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such patent rights.
This document has been prepared under a mandate given to CENELEC by the European Commission and the European Free Trade Association. Endorsement notice The text of the International Standard IEC 61158-4-20:2014 was approved by CENELEC as a European Standard without any modification. In the official version, for bibliography, the following notes have to be added for the standards indicated: IEC 61158-1:2014 NOTE Harmonised as EN 61158-1:2014 IEC 61158-3-20:2014 NOTE Harmonised as EN 61158-3-20:2014 IEC 61158-5-20:2014
NOTE Harmonised as EN 61158-5-20:2014 IEC 61784-1 NOTE Harmonised as EN 61784-1 IEC 61784-2 NOTE Harmonised as EN 61784-2 IEC 62591:2010 NOTE Harmonised as EN 62591:2010 SIST EN 61158-4-20:2015
- 3 - EN 61158-4-20:2014
Annex ZA (normative)
Normative references to international publications with their corresponding European publications
The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
NOTE 1 When an International Publication has been modified by common modifications, indicated by (mod), the relevant EN/HD applies.
NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available here: www.cenelec.eu.
Publication Year Title EN/HD Year IEC 61158-2 2014
Industrial communication networks - Fieldbus specifications
Part 2: Physical layer specification and service definition EN 61158-2 2014
IEC 61158-6-20 2014
Industrial communication networks - Fieldbus specifications
Part 6-20: Application layer protocol specification - Type 20 elements EN 61158-6-20 2014 ISO/IEC 7498-1 -
Information technology - Open Systems Interconnection - Basic reference model: The basic model - -
ISO/IEC 7498-3 -
Information technology - Open Systems Interconnection - Basic reference model: Naming and addressing - -
ISO/IEC 10731 -
Information technology - Open Systems Interconnection - Basic Reference Model - Conventions for the definition of OSI services - -
SIST EN 61158-4-20:2015
SIST EN 61158-4-20:2015
IEC 61158-4-20 Edition 1.0 2014-08 INTERNATIONAL STANDARD NORME INTERNATIONALE Industrial communication networks – Fieldbus specifications –
Part 4-20: Data-link layer protocol specification – Type 20 elements
Réseaux de communication industriels – Spécifications des bus de terrain –
Partie 4-20: Spécification du protocole de la couche liaison de données –
Éléments de type 20
INTERNATIONAL ELECTROTECHNICAL COMMISSION COMMISSION ELECTROTECHNIQUE INTERNATIONALE X ICS 25.040.40; 35.100.20; 35.110 PRICE CODE CODE PRIX ISBN 978-2-8322-1728-3
® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale ®
Warning! Make sure that you obtained this publication from an authorized distributor.
Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé. SIST EN 61158-4-20:2015 colourinside
– 2 – IEC 61158-4-20:2014 © IEC 2014 CONTENTS FOREWORD . 4 INTRODUCTION . 6 1 Scope . 7
General . 7 1.1 Specifications . 7 1.2 Procedures . 7 1.3 Applicability . 7 1.4 Conformance . 7 1.52 Normative references . 8 3 Terms, definitions, symbols and abbreviations . 8
Reference model terms and definitions . 8 3.1 Service convention terms and definitions . 9 3.2 Common terms and definitions . 10 3.3 Additional Type 20 definitions . 12 3.4 Common symbols and abbreviations . 18 3.5 Data units . 18 3.5.1 Miscellaneous . 18 3.5.2 Additional Type 20 symbols and abbreviations . 19 3.64 Data-link layer protocol specification . 20
Overview . 20 4.1 Parameters, timers and variables . 21 4.2 Parameters . 21 4.2.1 Timers . 22 4.2.2 Variables . 22 4.2.3 Logical link control . 23 4.3 General DLPDU structure . 23 4.3.1 DLPDU specific encoding and procedures . 26 4.3.2 Framing . 27 4.3.3 Error detection . 27 4.3.4 Slave response to communication error . 28 4.3.5 Medium access control . 30 4.4 Overview . 30 4.4.1 Master controlled medium access . 31 4.4.2 Burst mode controlled medium access . 32 4.4.3 Token passing summary . 32 4.4.4 XMIT machine . 33 4.4.5 RECV machine . 34 4.4.6 Slave MAC machine . 35 4.4.7 Master MAC machine . 38 4.4.8 DL-management-information . 41 4.5Bibliography . 42
Figure 1 – Relationships of DLSAPs, DLSAP-addresses and group DL-addresses . 11 Figure 2 – DLPDU Structure . 23 Figure 3 – Delimiter Structure . 23 Figure 4 – Construction of 1-octet address field . 24 SIST EN 61158-4-20:2015
IEC 61158-4-20:2014 © IEC 2014 – 3 – Figure 5 – Construction of 5-octet address field . 25 Figure 6 – APDU format . 25 Figure 7 – DLPDU framing . 27 Figure 8 – Two dimensional parity detection . 28 Figure 9 – Communication error response DLL payload . 29 Figure 10 – MAC state machines . 31 Figure 11 – Master controlled medium access . 31 Figure 12 – Burst mode controlled medium access . 32 Figure 13 – XMIT state machine . 33 Figure 14 – RECV state machine . 34 Figure 15 – Slave MAC state machine . 36 Figure 16 – Master MAC state machine . 38
Table 1 – Slave response to communication error . 29 Table 2 – Communication error code values . 29 Table 3 – Token passing . 32 Table 4 – XMIT state transitions . 33 Table 5 – RECV state transitions . 35 Table 6 – Slave MAC state transitions . 37 Table 7 – Master MAC state transitions. 39 Table 8 – Master DL parameters . 41 Table 9 – Slave DL parameters . 41
SIST EN 61158-4-20:2015
– 4 – IEC 61158-4-20:2014 © IEC 2014 INTERNATIONAL ELECTROTECHNICAL COMMISSION ____________
INDUSTRIAL COMMUNICATION NETWORKS –
FIELDBUS SPECIFICATIONS –
Part 4-20: Data-link layer protocol specification –
Type 20 elements
FOREWORD 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with may participate in this preparatory work. International, governmental and non-governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for Standardization (ISO) in accordance with conditions determined by agreement between the two organizations. 2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international consensus of opinion on the relevant subjects since each technical committee has representation from all interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any misinterpretation by any end user. 4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications transparently to the maximum extent possible in their national and regional publications. Any divergence between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter. 5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any services carried out by independent certification bodies. 6) All users should ensure that they have the latest edition of this publication. 7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and members of its technical committees and IEC National Committees for any personal injury, property damage or other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is indispensable for the correct application of this publication. 9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent rights. IEC shall not be held responsible for identifying any or all such patent rights. Attention is drawn to the fact that the use of the associated protocol type is restricted by its intellectual-property-right holders. In all cases, the commitment to limited release of intellectual-property-rights made by the holders of those rights permits a layer protocol type to be used with other layer protocols of the same type, or in other type combinations explicitly authorized by its intellectual-property-right holders. NOTE Combinations of protocol types are specified in IEC 61784-1 and IEC 61784-2. International Standard IEC 61158-4-20 has been prepared by subcommittee 65C: Industrial networks, of IEC technical committee 65: Industrial-process measurement, control and automation.
SIST EN 61158-4-20:2015
IEC 61158-4-20:2014 © IEC 2014 – 5 – The text of this standard is based on the following documents: FDIS Report on voting 65C/762/FDIS 65C/772/RVD
Full information on the voting for the approval of this standard can be found in the report on voting indicated in the above table. This publication has been drafted in accordance with the ISO/IEC Directives, Part 2. A list of all parts of the IEC 61158 series, published under the general title Industrial communication networks – Fieldbus specifications, can be found on the IEC web site. The committee has decided that the contents of this publication will remain unchanged until the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data related to the specific publication. At this date, the publication will be
• reconfirmed, • withdrawn, • replaced by a revised edition, or • amended.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates that it contains colours which are considered to be useful for the correct understanding of its contents. Users should therefore print this document using a colour printer.
SIST EN 61158-4-20:2015
– 6 – IEC 61158-4-20:2014 © IEC 2014 INTRODUCTION This part of IEC 61158 is one of a series produced to facilitate the interconnection of automation system components. It is related to other standards in the set as defined by the “three-layer” fieldbus reference model described in IEC 61158-1. The data-link protocol provides the data-link service by making use of the services available from the physical layer. The primary aim of this standard is to provide a set of rules for communication expressed in terms of the procedures to be carried out by peer data-link entities (DLEs) at the time of communication. These rules for communication are intended to provide a sound basis for development in order to serve a variety of purposes: a) as a guide for implementors and designers; b) for use in the testing and procurement of equipment; c) as part of an agreement for the admittance of systems into the open systems environment; d) as a refinement to the understanding of time-critical communications within OSI. This standard is concerned, in particular, with the communication and interworking of sensors, effectors and other automation devices. By using this standard together with other standards positioned within the OSI or fieldbus reference models, otherwise incompatible systems may work together in any combination.
SIST EN 61158-4-20:2015
IEC 61158-4-20:2014 © IEC 2014 – 7 – INDUSTRIAL COMMUNICATION NETWORKS –
FIELDBUS SPECIFICATIONS –
Part 4-20: Data-link layer protocol specification –
Type 20 elements
1 Scope
General 1.1The data-link layer provides basic time-critical messaging communications between devices in an automation environment. This protocol provides a means of connecting devices through a partial mesh network, such that most failures of an interconnection between two devices can be circumvented. In common practice the devices are interconnected in a non-redundant hierarchical manner reflecting application needs
Specifications 1.2This International Standard specifies 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) the structure of the fieldbus DLPDUs used for the transfer of data and control information by the protocol of this standard, and their representation as physical interface data units.
Procedures 1.3The procedures are defined in terms of a) the interactions between peer DL-entities (DLEs) through the exchange of fieldbus DLPDUs; b) the interactions between a DL-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 Ph-service provider in the same system through the exchange of Ph-service primitives.
Applicability 1.4These procedures are applicable to instances of communication between systems which support time-critical communications services within the data-link layer of the OSI or fieldbus reference models, and which 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-critical communications needs.
Conformance 1.5This International Standard also specifies conformance requirements for systems implementing these procedures. This standard does not contain tests to demonstrate compliance with such requirements. SIST EN 61158-4-20:2015
– 8 – IEC 61158-4-20:2014 © IEC 2014 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. NOTE All parts of the IEC 61158 series, as well as IEC 61784-1 and IEC 61784-2 are maintained simultaneously. Cross-references to these documents within the text therefore refer to the editions as dated in this list of normative references. IEC 61158-2:2014, Industrial communication networks – Fieldbus specifications – Part 2: Physical layer specification and service definition IEC 61158-6-20:2014, Industrial communication networks – Fieldbus specifications – Part 6-20: Application layer protocol specification – Type 20 elements ISO/IEC 7498-1, Information technology – Open Systems Interconnection – Basic Reference Model: The Basic Model ISO/IEC 7498-3, Information technology – Open Systems Interconnection – Basic Reference Model: Naming and addressing ISO/IEC 10731, Information technology – Open Systems Interconnection – Basic Reference Model – Conventions for the definition of OSI services 3 Terms, definitions, symbols and abbreviations For the purposes of this document, the following terms, definitions, symbols, abbreviations and conventions apply.
Reference model terms and definitions 3.1This standard is based in part on the concepts developed in ISO/IEC 7498-1 and ISO/IEC 7498-3, and makes use of the following terms defined therein: 3.1.1 called-DL-address [7498-3] 3.1.2 calling-DL-address [7498-3] 3.1.3 centralized multi-end-point-connection [7498-1] 3.1.4 correspondent (N)-entities
correspondent DL-entities
(N=2)
correspondent Ph-entities
(N=1) [7498-1] 3.1.5 demultiplexing [7498-1] 3.1.6 DL-address [7498-3] 3.1.7 DL-address-mapping [7498-1] 3.1.8 DL-connection [7498-1] 3.1.9 DL-connection-end-point [7498-1] 3.1.10 DL-connection-end-point-identifier [7498-1] 3.1.11 DL-connection-mode transmission [7498-1] 3.1.12 DL-connectionless-mode transmission [7498-1] 3.1.13 DL-data-sink [7498-1] 3.1.14 DL-data-source [7498-1] 3.1.15 DL-duplex-transmission [7498-1] 3.1.16 DL-facility [7498-1] 3.1.17 DL-local-view [7498-3] 3.1.18 DL-name [7498-3] 3.1.19 DL-protocol [7498-1] 3.1.20 DL-protocol-connection-identifier [7498-1] 3.1.21 DL-protocol-control-information [7498-1] SIST EN 61158-4-20:2015
IEC 61158-4-20:2014 © IEC 2014 – 9 – 3.1.22 DL-protocol-data-unit [7498-1] 3.1.23 DL-protocol-version-identifier [7498-1] 3.1.24 DL-relay [7498-1] 3.1.25 DL-service-connection-identifier [7498-1] 3.1.26 DL-service-data-unit [7498-1] 3.1.27 DL-simplex-transmission [7498-1] 3.1.28 DL-subsystem [7498-1] 3.1.29 DL-user-data [7498-1] 3.1.30 flow control [7498-1] 3.1.31 layer-management [7498-1] 3.1.32 multiplexing [7498-3] 3.1.33 naming-(addressing)-authority [7498-3] 3.1.34 naming-(addressing)-domain [7498-3] 3.1.35 naming-(addressing)-subdomain [7498-3] 3.1.36 (N)-entity
DL-entity
Ph-entity [7498-1] 3.1.37 (N)-interface-data-unit
DL-service-data-unit
(N=2)
Ph-interface-data-unit
(N=1) [7498-1] 3.1.38 (N)-layer
DL-layer
(N=2)
Ph-layer
(N=1) [7498-1] 3.1.39 (N)-service
DL-service
(N=2)
Ph-service
(N=1) [7498-1] 3.1.40 (N)-service-access-point
DL-service-access-point
(N=2)
Ph-service-access-point
(N=1) [7498-1] 3.1.41 (N)-service-access-point-address
DL-service-access-point-address
(N=2)
Ph-service-access-point-address
(N=1) [7498-1] 3.1.42 peer-entities [7498-1] 3.1.43 Ph-interface-control-information [7498-1] 3.1.44 Ph-interface-data [7498-1] 3.1.45 primitive name [7498-3] 3.1.46 reassembling [7498-1] 3.1.47 recombining [7498-1] 3.1.48 reset [7498-1] 3.1.49 responding-DL-address [7498-3] 3.1.50 routing [7498-1] 3.1.51 segmenting [7498-1] 3.1.52 sequencing [7498-1] 3.1.53 splitting [7498-1] 3.1.54 synonymous name [7498-3] 3.1.55 systems-management [7498-1]
Service convention terms and definitions 3.2This standard also makes use of the following terms defined in ISO/IEC 10731 as they apply to the data-link layer: 3.2.1 acceptor 3.2.2 asymmetrical service 3.2.3 confirm (primitive);
requestor.deliver (primitive) 3.2.4 deliver (primitive) 3.2.5 DL-confirmed-facility 3.2.6 DL-facility 3.2.7 DL-local-view 3.2.8 DL-mandatory-facility SIST EN 61158-4-20:2015
– 10 – IEC 61158-4-20:2014 © IEC 2014 3.2.9 DL-non-confirmed-facility 3.2.10 DL-provider-initiated-facility 3.2.11 DL-provider-optional-facility 3.2.12 DL-service-primitive;
primitive 3.2.13 DL-service-provider 3.2.14 DL-service-user 3.2.15 DLS-user-optional-facility 3.2.16 indication (primitive);
acceptor.deliver (primitive) 3.2.17 multi-peer 3.2.18 request (primitive);
requestor.submit (primitive) 3.2.19 requestor 3.2.20 response (primitive);
acceptor.submit (primitive) 3.2.21 submit (primitive) 3.2.22 symmetrical service
Common terms and definitions 3.3For the purposes of this document, the following terms and definitions apply. NOTE Many definitions are common to more than one protocol Type; they are not necessarily used by all protocol Types.
3.3.1DL-segment,
link,
local link single DL-subnetwork in which any of the connected DLEs may communicate directly, without any intervening DL-relaying, whenever all of those DLEs that are participating in an instance of communication are simultaneously attentive to the DL-subnetwork during the period(s) of attempted communication
3.3.2DLSAP distinctive point at which DL-services are provided by a single DL-entity to a single higher-layer entity Note 1 to entry:
This definition, derived from ISO/IEC 7498-1, is repeated here to facilitate understanding of the critical distinction between DLSAPs and their DL-addresses, see Figure 1. SIST EN 61158-4-20:2015
IEC 61158-4-20:2014 © IEC 2014 – 11 – PhSAP PhSAP DL-entity DLS-user-entity DLS
...
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