IEC IEC 61158-4-21 Edition 3.0 2023-03 INTERNATIONAL STANDARD NORME NTERNATIONALE Industrial communication networks - Fieldbus specifications - Part 4-21: Data-link layer protocol specification - Type 21 elements Réseaux de communication industriels - Specifications des bus de terrain - Partie 4-21: Specification du protocole de la couche liaison de donnees - Eléments de type 21 IEC 61158-4-21:2023-03(en-fr) A THIS PUBLICATION IS COPYRIGHT PROTECTED Copyright @ 2023 IEC, Geneva, Switzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from eitherIECorIEC'smemberNational Committee inthecountry ofthe requester.IfyouhaveanyquestionsaboutIEC copyright or have an enquiry about obtaining additional rights to this publication, piease contact the address below or your local IEC member National Committee for further information. Droits de reproduction réservés. Sauf indication contraire,aucune partie de cette publication ne peut étre reproduite ni utilisée sous quelque formeque ce soit et paraucun procedé,électronique ou mécanique,y comprisla photocopieet les microfilms, sans I'accord écrit de I'EC ou du Comite national de I'IEc du pays du demandeur. Si vous avez des questions sur le copyright de I'EC ou si vous desirez obtenir des droits supplementaires sur cette publication, utilisez les coordonnees ci-apres ou contactez le Comite national de I'lEC de votre pays de residence. IEC Secretariat Tel.: +41 22 919 0211 3, rue de Varembé [email protected] CH-1211 Geneva20 www.iec.ch Switzerland About the IEC The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes International Standards for all electrical, electronic and related technologies. About IECpublications latest edition, a corrigendum or an amendment might have been published. IECpublicationssearch-webstore.iec.ch/advsearchform IEC Products &Services Portal-products.iec.ch The advanced search enables to find IEC publications by a variety ofcriteria(referencenumber,text, technical publications previews.With a subscription you will always have committee, ...). It also gives information on projects, replaced access to up to date content tailored to yourneeds. and withdrawn publications. Electropedia-www.electropedia.org IEC Just Published-webstore.iec.ch/justpublished The world's leading online dictionary on electrotechnology, Stay up to date on all new IEC publications. Just Published details all new publications released. Available online and once and French, with equivalent terms in 19 additional languages. a month by email. Also known as the International Electrotechnical Vocabulary (IEV) online. IEC Customer Service Centre - webstore.iec.ch/csc If you wish to give us yourfeedback on this publication or need further assistance, please contact the Customer Service Centre:[email protected] A propos de I'IEC La Commission Electrotechnique Internationale (IEC) est la premiere organisation mondiale qui élabore et publie des Normes internationales pour tout ce qui a trait a I'electricite, a i'electronique et aux technologies apparentees. Apropos des publications IEC Le contenu technique des publications IEC est constamment revu. Veuillez vous assurer que vous possédez I'édition la plusrécente,un corrigendumouamendementpeut avoiréte publie IEc Products & Services Portal - products.iec.ch RecherchedepublicationsIEC webstore.iec.ch/advsearchform Découvrez notre puissant moteur de recherche et consultez La recherche avancee permet de trouver des publications IEC gratuitement tous les apercus des publications.Avec un en utilisant differents criteres (numero de reference,texte, abonnement,vous aurez toujours acces a un contenu a jour comite d'études,...).Elle donneaussides informations surles adapteavosbesoins. projets et les publications remplacees ou retirees.