EN 62056-53:2007

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Messung der elektrischen Energie - Zählerstandsübertragung, Tarif- und Laststeuerung - Teil 53: COSEM-AnwendungsschichtEquipements de mesure de l'énergie électrique - Echange des données pour la lecture des compteurs, le contrôle des tarifs et de la charge -- Partie 53: Couche application COSEMElectricity metering - Data exchange for meter reading, tariff and load control -- Part 53: COSEM application layer91.140.50Sistemi za oskrbo z elektrikoElectricity supply systems35.100.70Uporabniški slojApplication layer17.220.20Measurement of electrical and magnetic quantitiesICS:Ta slovenski standard je istoveten z:EN 62056-53:2007SIST EN 62056-53:2007en,de01-november-2007SIST EN 62056-53:2007SLOVENSKI
STANDARDSIST EN 62056-53:20041DGRPHãþD

EUROPEAN STANDARD EN 62056-53 NORME EUROPÉENNE
EUROPÄISCHE NORM April 2007
CENELEC European Committee for Electrotechnical Standardization Comité Européen de Normalisation Electrotechnique Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: rue de Stassart 35, B - 1050 Brussels
© 2007 CENELEC -
All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 62056-53:2007 E
ICS 91.140.50; 35.100.70 Supersedes EN 62056-53:2002
English version
Electricity metering -
Data exchange for meter reading, tariff and load control -
Part 53: COSEM application layer (IEC 62056-53:2006)
Equipements de mesure
de l'énergie électrique -
Echange des données
pour la lecture des compteurs,
le contrôle des tarifs et de la charge -
Partie 53: Couche application COSEM (CEI 62056-53:2006)
Messung der elektrischen Energie -
Zählerstandsübertragung,
Tarif- und Laststeuerung -
Teil 53: COSEM-Anwendungsschicht (IEC 62056-53:2006)
This European Standard was approved by CENELEC on 2007-02-01. 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 Central Secretariat 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 Central Secretariat has the same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Cyprus, the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom.
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Foreword The text of document 13/1387/FDIS, future edition 2 of IEC 62056-53, prepared by IEC TC 13, Electrical energy measurement, tariff- and load control, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as EN 62056-53 on 2007-02-01. This European Standard supersedes EN 62056-53:2002. The main changes with respect to EN 62056-53:2002 are as follows: − the protocol of the COSEM-RELEASE service has been changed: depending on the communication profile used, these services may rely on the ACSE A_RELEASE services; − the parsing order of the AARQ APDU has been changed; − handling of repeated application association requests has been simplified; − the Service_Class parameter of the COSEM-OPEN service is now linked to the response allowed field of the xDLMS-Initiate.request APDU; − the Service_Class parameter of COSEM services for data exchange using LN referencing is now linked to bit 6 of the Invoke-Id-And-Priority parameter; − a new, optional EXCEPTION APDU has been introduced. The server may send back this APDU after an erroneous service request; − a general part about using the COSEM application layer in various communication profiles has been added; − the description of using the COSEM Application layer in the 3-layer, connection-oriented, HDLC based communication profile has been amended; − a new, TCP-UDP/IP based communication profile has been defined. The following dates were fixed: – latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement
(dop)
2007-11-01 – latest date by which the national standards conflicting
with the EN have to be withdrawn
(dow)
2010-02-01 The International Electrotechnical Commission (IEC) and CENELEC draw attention to the fact that it is claimed that compliance with this International Standard / European Standard may involve the use of a maintenance service concerning the stack of protocols on which the present standard IEC 62056-53 / EN 62056-53 is based.
The IEC and CENELEC take no position concerning the evidence, validity and scope of this maintenance service.
The provider of the maintenance service has assured the IEC that he is willing to provide services under reasonable and non-discriminatory terms and conditions with applicants throughout the world. In this respect, the statement of the provider of the maintenance service is registered with the IEC. Information may be obtained from:
DLMS 1) User Association Geneva / Switzerland www.dlms.ch
1) Device Language Message Specification SIST EN 62056-53:2007

- 3 - EN 62056-53:2007 Annex ZA has been added by CENELEC. __________ Endorsement notice The text of the International Standard IEC 62056-53:2006 was approved by CENELEC as a European Standard without any modification. In the official version, for Bibliography, the following note has to be added for the standard indicated: ISO/IEC 7498-1 NOTE
Harmonized as EN ISO/IEC 7498-1:1995 (not modified). __________
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Annex ZA
(normative)
Normative references to international publications with their corresponding European publications
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
NOTE
When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD applies.
Publication Year Title EN/HD Year
IEC 60050-300 2001 International Electrotechnical Vocabulary - Electrical and electronic measurements and measuring instruments -
Part 311: General terms relating to measurements - Part 312: General terms relating to electrical measurements -
Part 313: Types of electrical measuring instruments -
Part 314: Specific terms according to the type of instrument - -
IEC 61334-4-41 1996 Distribution automation using distribution line carrier systems -
Part 4: Data communication protocols - Section 41: Application protocols - Distribution line message specification EN 61334-4-41 1996
IEC 61334-6 2000 Distribution automation using distribution line carrier systems -
Part 6: A-XDR encoding rule EN 61334-6 2000
IEC/TR 62051 1999 Electricity metering - Glossary of terms - -
IEC/TR 62051-1
2004 Electricity metering - Data exchange
for meter reading, tariff and load control - Glossary of terms -
Part 1: Terms related to data exchange with metering equipment using DLMS/COSEM - -
IEC 62056-21 2002 Electricity metering - Data exchange
for meter reading, tariff and load control -
Part 21: Direct local data exchange EN 62056-21 2002
IEC 62056-42 2002 Electricity metering - Data exchange
for meter reading, tariff and load control -
Part 42: Physical layer services and procedures for connection-oriented asynchronous data exchange EN 62056-42 2002
IEC 62056-46 A1 2002 2006 Electricity metering - Data exchange
for meter reading, tariff and load control -
Part 46: Data link layer using HDLC protocol EN 62056-46 A1 2002 2007
- 5 - EN 62056-53:2007 Publication Year Title EN/HD Year IEC 62056-47 2006 Electricity metering - Data exchange
for meter reading, tariff and load control -
Part 47: COSEM transport layers for IPv4 networks EN 62056-47 2007
IEC 62056-61 2006 Electricity metering - Data exchange
for meter reading, tariff and load control -
Part 61: Object identification system (OBIS) EN 62056-61 2007
IEC 62056-62 2006 Electricity metering - Data exchange
for meter reading, tariff and load control -
Part 62: Interface classes EN 62056-62 2007
ISO/IEC 8649 1996 Information technology - Open systems interconnection - Service definition for the Association Control Service Element
- -
ISO/IEC 8650-1 1996 Information technology - Open systems interconnection - Connection-oriented protocol for the association control service Information technology - ASN.1 encoding rules: Protocol specification - -
ISO/IEC 8824 Series Information technology - Abstract Syntax Notation One (ASN.1) - -
ISO/IEC 8825 Series Information technology - ASN.1 encoding rules - -
ISO/IEC 13239 2002 Information technology - Telecommunications and information exchange between systems - High-level data link control (HDLC) procedures - -
STD 0005 1981 Internet Protocol - -
STD 0006 1980 User Datagram Protocol - -
STD 0007 1981 Transmission Control Protocol - -
INTERNATIONAL STANDARD IEC62056-53 Second edition2006-12 Electricity metering –
Data exchange for meter reading,
tariff and load control – Part 53: COSEM application layer © IEC 2006
⎯
Copyright - all rights reserved 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 the publisher. International Electrotechnical Commission,
3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, SwitzerlandTelephone: +41 22 919 02 11 Telefax: +41 22 919 03 00 E-mail: inmail@iec.ch
Web: www.iec.ch XG For price, see current cataloguePRICE CODE
Commission Electrotechnique InternationaleInternational Electrotechnical CommissionSIST EN 62056-53:2007

– 2 – 62056-53 © IEC:2006(E) CONTENTS FOREWORD.5
1 Scope.7 2 Normative references.7 3 Terms, definitions and abbreviations.8 4 The COSEM communications framework.10 4.1 Client/server type operation, communication profiles.10 4.2 Connection (association) oriented operation.12 5 Overview: the COSEM application layer.12 5.1 Specification method.12 5.2 Application layer structure.12 5.3 Service specification.13 5.4 Layer management services.15 5.5 Protocol specification.15 6 COSEM application layer – Service specification.16 6.1 Summary of services.16 6.2 Application association establishment and release.16 6.3 Special application associations.17 6.4 Data communication.18 6.5 Client COSEM application layer services.19 6.6 Server COSEM application layer services.38 6.7 Summary of COSEM application layer services and service parameters.55 7 COSEM application layer protocol specification.59 7.1 State definitions for the client side control function.59 7.2 State definitions for the server side control function.61 7.3 Protocol for application association establishment/release.62 7.4 Protocol for data communications.74 8 Specification of COSEM data types.89 8.1 The COSEM APDUs.89 8.2 The ACSE APDUs.90 8.3 Useful types.93 8.4 The xDLMS-Initiate.request/response/ConfirmedServiceError PDUs.98 8.5 The conformance block.98 8.6 Definition of APDUs for data communication.99
Annex A (normative)
The xDLMS application service element.105 Annex B (normative)
Using the COSEM Application Layer in various communication profiles.107 Annex C (informative)
AARQ and AARE encoding examples.126 Annex D (informative)
Data model and protocol.138
Bibliography.139
INDEX.142
62056-53 © IEC:2006(E) – 3 – Figure 1 – Client/server relationship in COSEM.10 Figure 2 – Exchanging messages via the communication protocol.11 Figure 3 – The COSEM application layer on the top of various lower layer stacks.11 Figure 4 – A complete communication session in the CO environment.12 Figure 5 – The structure of the COSEM application layers.13 Figure 6 – Structure of the COSEM AL when the server is using SN references.15 Figure 7 – Summary of COSEM application layer services.16 Figure 8 – Normal service sequence for the COSEM-OPEN service.17 Figure 9 – Client side services for application association establishment.19 Figure 10 – Client side services for releasing an application association.23 Figure 11 – Client side data communication services.26 Figure 12 – Client side services for event notification.35 Figure 13 – Server side services for application association establishment.38 Figure 14 – Server side services for releasing an application association.40 Figure 15 – Server side data communications services using LN referencing.44 Figure 16 – Partial state machine for the client side control function.60 Figure 17 – Partial state machine for the server side control function.61 Figure 18 – MSC for successful application association establishment preceded by a successful lower layer connection establishment.63 Figure 19 – Graceful association release using the A-RELEASE service.69 Figure 20 – Graceful release of an application association
by disconnection the supporting layer.70 Figure 21 – Aborting an application association following a PH-ABORT.indication.71 Figure 22 – MSC for a confirmed GET service in case of success.75 Figure 23 – MSC for a confirmed SET service in case of success.75 Figure 24 – MSC for the SET service in case of failure.76 Figure 25 – MSC for the ACTION service (simplest case).76 Figure 26 – Long data with the GET service in three data blocks.81 Figure 27 – Long data transfer in three data blocks with the SET service.83 Figure 28 – Long data transfer with the ACTION service.85 Figure 29 – MSC for the ReadRequest/Response services.87 Figure B.1 – Identification/addressing scheme in the 3-layer, connection-oriented, HDLC based communication profile.110 Figure B.2 – Data link layer services provided to and used
by the client COSEM application layer.111 Figure B.3 – Data link layer services provided to and used
by the server COSEM application layer.112 Figure B.4 – Example: EventNotificaton triggered by the client.115 Figure B.5 – Multi-drop configuration and its model.116 Figure B.6 – Master/ Slave operation on the multi-drop bus.116 Figure B.7 – COSEM as a standard Internet application protocol.118 Figure B.8 – Examples for lower-layer protocols in the TCP-UDP/IP based profiles.119 Figure B.9 – Identification/addressing scheme in the TCP-UDP/IP based profile(s).120 Figure B.10 – Summary of TCP/UDP layer services on the client and server side.121 Figure D.1 – The three-step approach of COSEM.138 SIST EN 62056-53:2007

– 4 – 62056-53 © IEC:2006(E)
Table 1 – Mapping between client side LN and server side SN referencing services.37 Table 2 – Application layer services – summary.55 Table 3 – Summary of the service parameters in the COSEM-OPEN service primitives.56 Table 4 – Summary of the service parameters
in the COSEM-RELEASE service primitives.57 Table 5 – Summary of the service parameters
in the COSEM-ABORT service primitives.57 Table 6 – Summary of the service parameters in the COSEM GET service primitives.57 Table 7 – Summary of the service parameters in the COSEM SET service primitives.58 Table 8 – Summary of the service parameters in the COSEM ACTION service primitives.58 Table 9 – Summary of the service parameters in the
COSEM EventNotification service primitives.59 Table 10 – Mapping between the EventNotification and InformationReport services.88 Table B.1 – Application associations and data exchange in the 3-layer, connection-oriented, HDLC based profile.113 Table B.2 –Application associations and data exchange
in the TCP-UDP/IP based profile.123 SIST EN 62056-53:2007

62056-53 © IEC:2006(E) – 5 – INTERNATIONAL ELECTROTECHNICAL COMMISSION ____________
ELECTRICITY METERING –
DATA EXCHANGE FOR METER READING,
TARIFF AND LOAD CONTROL –
Part 53: COSEM application layer
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 provides no marking procedure to indicate its approval and cannot be rendered responsible for any equipment declared to be in conformity with an IEC Publication. 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. The International Electrotechnical Commission (IEC) draws attention to the fact that it is claimed that compliance with this International Standard may involve the use of a maintenance service concerning the stack of protocols on which the present standard IEC 62056-53 is based. The IEC takes no position concerning the evidence, validity and scope of this maintenance service. The provider of the maintenance service has assured the IEC that he is willing to provide services under reasonable and non-discriminatory terms and conditions with applicants throughout the world. In this respect, the statement of the provider of the maintenance service is registered with the IEC. Information may be obtained from: DLMS1 User Association Geneva / Switzerland www.dlms.ch International Standard IEC 62056-53 has been prepared by IEC technical committee 13: Equipment for electrical energy measurement and load control. ——————— 1 Device Language Message Specification SIST EN 62056-53:2007

– 6 – 62056-53 © IEC:2006(E) This standard cancels and replaces the first edition which was published in 2002. It constitutes a technical revision. The main changes with respect to the previous edition are as follows: • the protocol of the COSEM-RELEASE service has been changed: depending on the communication profile used, these services may rely on the ACSE A_RELEASE services; • the parsing order of the AARQ APDU has been changed; • handling of repeated application association requests has been simplified; • the Service_Class parameter of the COSEM-OPEN service is now linked to the response-allowed field of the xDLMS-Initiate.request APDU; • the Service_Class parameter of COSEM services for data exchange using LN referencing is now linked to bit 6 of the Invoke-Id-And-Priority parameter; • a new, optional EXCEPTION APDU has been introduced. The server may send back this APDU after an erroneous service request; • a general part about using the COSEM application layer in various communication profiles has been added; • the description of using the COSEM Application layer in the 3-layer, connection-oriented, HDLC based communication profile has been amended; • a new, TCP-UDP/IP based communication profile has been defined. The text of this standard is based on the following documents: FDIS Report on voting 13/1387/FDIS 13/1398/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 IEC 62056 series, published under the general title Electricity metering – Data exchange for meter reading, tariff and load control, can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until the maintenance result 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. A bilingual version of the publication may be issued at a later date. SIST EN 62056-53:2007

62056-53 © IEC:2006(E) – 7 – ELECTRICITY METERING –
DATA EXCHANGE FOR METER READING,
TARIFF AND LOAD CONTROL –
Part 53: COSEM application layer
1 Scope This part of IEC 62056 specifies the COSEM application layer in terms of structure, services and protocols for COSEM clients and servers, and defines how to use the COSEM application layer in various communication profiles. It defines services for establishing and releasing application associations, and data communication services for accessing the methods and attributes of COSEM interface objects, defined in IEC 62056-62, using either logical name (LN) or short name (SN) referencing. Annex A describes the xDLMS application service element. Annex B defines how to use the COSEM application layer in various communication profiles. Annex C includes encoding examples for APDUs. Annex D gives an explanation of the role of data models and protocols in electricity meter data exchange. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 60050-300:2001, International Electrotechnical Vocabulary (IEV) – Electrical and electronic measurements and measuring instruments – Part 311: General terms relating to measurements – Part 312: General terms relating to electrical measurements – Part 313: Types of electrical measuring instruments – Part 314: Specific terms according to the type of instrument IEC 61334-4-41:1996, Distribution automation using distribution line carrier systems – Part 4: Data communication protocols – Section 41: Application protocols – Distribution line message specification IEC 61334-6:2000, Distribution automation using distribution line carrier systems – Part 6: A-XDR encoding rule IEC 62051:1999, Electricity metering – Glossary of terms IEC 62051-1:2004, Electricity metering – Data exchange for meter reading, tariff and load control – Glossary of Terms – Part 1: Terms related to data exchange with metering equipment using DLMS/COSEM IEC 62056-21:2002, Electricity metering – Data exchange for meter reading, tariff and load control – Part 21: Direct local data exchange SIST EN 62056-53:2007

– 8 – 62056-53 © IEC:2006(E) IEC 62056-42:2002, Electricity metering – Data exchange for meter reading, tariff and load control – Part 42: Physical layer services and procedures for connection-oriented asynchronous data exchange IEC 62056-46:2002, Electricity metering – Data exchange for meter reading, tariff and load control – Part 46: Data link layer using HDLC protocol
Amendment 12 IEC 62056-47, Electricity metering – Data exchange for meter reading, tariff and load control – Part 47: COSEM transport layer for IP networks
IEC 62056-61, Ed.2, Electricity metering – Data exchange for meter reading, tariff and load control – Part 61: Object identification system (OBIS)
IEC 62056-62, Ed.2, Electricity metering – Data exchange for meter reading, tariff and load control – Part 62: Interface classes
ISO/IEC 8649:1996, Information technology – Open Systems Interconnection – Service definition for the Association Control Service Element ISO/IEC 8650-1:1996, Information technology – Open systems interconnection – Connection-oriented protocol for the Association Control Service Element: Protocol specification ISO/IEC 8824, Information technology – Abstract Syntax Notation One (ASN.1) ISO/IEC 8825, Information technology – ASN.1 encoding rules ISO/IEC 13239:2002, Information technology – Telecommunications and information exchange between systems – High-level data link control (HDLC) procedures STD0005 – Internet Protocol Author: J. Postel Date: September 1981 Also: RFC0791, RFC0792, RFC0919, RFC0922, RFC0950, RFC1112 STD0006 – User Datagram Protocol Author: J. Postel Date: 28 August 1980 Also: RFC0768 STD0007 – Transmission Control Protocol Author: J. Postel Date: September 1981 Also: RFC0793 See also Bibliography for other related Internet RFCs. 3 Terms, definitions and abbreviations 3.1 Terms and definitions For the purposes of this part of IEC 62056, the definitions in IEC 60050-300, IEC 62051 and IEC 62051-1 apply. 3.2 Abbreviations .cnf .confirm service primitive .ind .indication service primitive ——————— 2 To be published. SIST EN 62056-53:2007

62056-53 © IEC:2006(E) – 9 – .req .request service primitive .res .response service primitive AA Application Association AARE Application Association REsponse AARQ Application Association ReQuest ACSE Application Control Service Element AE Application Entity AP Application Process APDU Application layer Protocol Data Unit API Application Programming Interface ARP Address Resolution Protocol ASE Application Service Element ASO Application Service Object ATM Asynchronous Transfer Mode A-XDR Adapted eXtended Data Representation BER Basic Encoding Rules CF Control function CO Connection Oriented COSEM COmpanion Specification for Energy Metering DLMS Device Language Message Specification DSAP Data link Service Access Point FDDI Fibre Distributed Data Interface FTP File Transfer Protocol GMT Greenwich Mean Time GSM Global System for Mobile communications HDLC High-level Data Link Control HLS High Level Security HTTP Hypertext Transfer Protocol IC Interface Class IETF Internet Engineering Task Force IP
Internet Protocol LAN Local Area Network LLC Logical Link Control (sub-layer) LLS Low Level Security LPDU LLC Protocol Data Unit LSAP LLC sub-layer Service Access Point LSB Least Significant Bit MAC Medium Access Control MD5 Message Digest Algorithm 5 MIB Management Information Base MSB Most Significant Bit MSC Message Sequence Chart OBIS OBject Identification System SIST EN 62056-53:2007

– 10 – 62056-53 © IEC:2006(E) OSI Open System Interconnection PDU Protocol Data Unit PPP Point-to-Point Protocol PSTN Public Switched Telephone Network RARP Reverse Address Resolution Protocol RFC Request For Comment RLRQ Release Request RLRE Release Response SAP Service Access Point SHA-1 Secure Hash Algorithm 1 SNMP Simple Network Management Protocol VAA Virtual Application Association xDLMS-ASE extended DLMS Application Service Element 4 The COSEM communications framework 4.1 Client/server type operation, communication profiles Communication with electricity metering equipment using the COSEM interface object model is based on the client/server paradigm where metering equipment3 plays the server role. In this environment, communication takes place always between a client and a server AP: in other words, the server AP provides remote services to the client AP. These services are provided via exchanging messages (SERVICE.requests/.responses) between the client and the server APs, as shown in Figure 1.
Client application Server application (COSEM device) SERVICE.request SERVICE.responseIEC
2070/06
Figure 1 – Client/server relationship in COSEM In general, the client and the server APs are located in separate devices; exchanging messages is done with the help of the communication protocol as shown in Figure 2.
——————— 3
The term metering equipment is an abstraction; consequently the equipment playing the role of a server may be any type of equipment for which this abstraction is suitable. SIST EN 62056-53:2007

62056-53 © IEC:2006(E) – 11 –
Client Application layer Intermediateprotocol layersPhysical layerServer .request.response.request.response Protocol Physical channelIEC
2071/06
Figure 2 – Exchanging messages via the communication protocol In general, communication protocols are structured in layers. The client and server COSEM applications use services of the highest protocol layer, that of the application layer: consequently, this is the only protocol layer containing COSEM specific element(s). This is called the xDLMS_ASE. All COSEM interface object related services – the xDLMS application protocol – are provided by this xDLMS_ASE. Other protocol layers are independent of the COSEM model. Consequently, the COSEM application layer can be placed on the top of a wide variety of lower protocol layer stacks, as shown in Figure 3.
xDLMS_ASE ACSEApplication layerN layer N-1 layer N layer N layer Physical layer Physical layerPhysical layer Profile 1 Profile 2 Profile M ……… IEC
2072/06
Figure 3 – The COSEM application layer on the top of various lower layer stacks SIST EN 62056-53:2007

– 12 – 62056-53 © IEC:2006(E) A complete protocol stack – including the application layer, a physical layer and all protocol layers between these extreme layers – is called a communication profile. A communication profile is characterized by the protocol layers included, their parameters, and by the type – connection-oriented or connectionless – of the ACSE4 included in the application layer. 4.2 Connection (association) oriented operation The xDLMS application protocol is a connection-oriented protocol. It means that the client and server APs can use the services of the xDLMS_ASE only when these APs are associated5. Therefore, in this environment a communication session consists of three phases, as shown in Figure 4.
Client applicationServer applicationPhase 1. Connection establishment Phase 2. Data communication Phase 3. Connection release t IEC
2073/06
Figure 4 – A complete communication session in the CO environment In the DLMS/COSEM environment, application association establishment is normally done by using the association request/response services of the standard association control service element. On the other hand, for the purposes of very simple devices, one-way communicating devices and for multicasting and broadcasting, pre-established application associations are also allowed; see 6.3.3. For such associations, there is no need to use the services of the ACSE: a full communication session may include only the data communication phase. (It can be considered that the connection establishment phase has been already done somewhere in the past.) 5 Overview: the COSEM application layer 5.1 Specification method
The COSEM application layer is specified in terms of structure, services, and protocols. 5.2 Application layer structure The main component of the client and server COSEM application layers is the COSEM ASO, which provides services to the COSEM AP, and uses services provided by the supporting lower layer. Both the client and server side COSEM ASO contain three mandatory components: • the ACSE. The task of this element is to establish, maintain, and release application associations. For the purposes of connection-oriented profiles, the connection-oriented ACSE, specified in ISO/IEC 8649 and ISO/IEC 8650-1 is used; ——————— 4 ACSE = Association Control Service Element 5 Application associations can be considered as application level connections. SIST EN 62056-53:2007

62056-53 © IEC:2006(E) – 13 – • the Extended DLMS application service element (xDLMS_ASE). The task of this element is to provide data communication services between COSEM APs. See also Annex A; • the Control function (CF). This element specifies how the ASO services invoke the appropriate service primitives of the ACSE and the xDLMS ASE and the services of the supporting layer. NOTE Both the client and the server COSEM ASO may contain other, optional application protocol components. Figure 5 shows ‘minimal’ COSEM ASOs, containing only the three mandatory components.
COSEM client ASO Client control function COSEM client ASO services Referencing by Logical Name Supporting layer services ClientxDLMS_ASE Client ACSE COSEM client application process COSEM server ASO
COSEM server ASO services Supporting layer services Server xDLMS _ASE ServerACSECOSEM server application process COSEM server application layer Protocol Applications (communications) (interface objects) WAN, LAN Server control functionSupporting layer
and
other protocol layers Supporting layer
and
other protocol layers Referencing by Logical Name COSEM client application layer IEC
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Figure 5 – The structure of the COSEM application layers The COSEM application layer performs also some functions of the OSI presentation layer: • for encoding the ACSE APDUS- AARQ, AARE, RLRQ, RLRE – BER encoding is used (ISO/IEC 8825); • for encoding the APDUs carrying the data communication services, A-XDR encoding is used (IEC 61334-6). 5.3 Service specification Service specifications cover the services required of, or by the COSEM client and server APs at the logical interfaces with the respective COSEM application layer, using connection-oriented procedures. Services provided by the COSEM ASO fall into three categories: • application association establishment and release; • data communication; • layer management. The client and server application layer services are specified in Clause 6. SIST EN 62056-53:2007

– 14 – 62056-53 © IEC:2006(E) 5.3.1 Services provided for application association establishment and release These services are the following: • COSEM-OPEN; • COSEM-RELEASE; • COSEM-ABORT. The COSEM-OPEN service is used during AA establishment phase and relies on the association request/response services of the ACSE. In the case of pre-established application associations (6.3.3) these services are not used. In certain COSEM communication profiles – for example in the 3-layer, connection-oriented, HDLC based profile – there is a one-to-one relationship between a confirmed AA and the supporting protocol layer connection. In this case, the COSEM-RELEASE service used during the association release phase does not rely on the ACSE A_RELEASE services. Confirmed AAs in these profiles are released simply by disconnecting the corresponding lower layer connection. Optionally, the COSEM-RELEASE service may rely on the ACSE A_RELEASE service. In some communication profiles, like in the TCP-UDP/IP based profile, using the ACSE A_RELEASE services for releasing COSEM AAs is mandatory. 5.3.2 Data communication services IEC 62056-62 specifies two referencing methods for COSEM servers: referencing by Logical Names (LN) and referencing by Short Names (SN). Therefore, two distinct service sets are specified for the server side xDLMS_ASE. One set uses exclusively LN references the other set uses exclusively SN references. Thus, these services are the following: • COSEM interface object attribute-related services: GET, SET for LN referencing and Read, Write, Unconfirmed Write for SN referencing; • COSEM interface object method-related services: ACTION (LN), Read, Write or UnconfirmedWrite (SN); • the EventNotification (LN), InformationReport (SN) services. The services rely on the services of the xDLMS_ASE. Most of these services contain references to attributes or methods of COSEM interface objects. The service set to be used on the server side during the data communications phase is negotiated during the association establishment phase using the conformance block, see 8.5. It shall not change during the lifetime of the established association. Using LN or SN services within a given AA is exclusive. Therefore, it can be considered that there are two, different server xDLMS_ASE-s: one providing services with Logical name references and another providing services with Short name references. The server application layer shall include one or both of these xDLMS_ASEs. NOTE A server could use both LN and SN referencing in different AAs. On the client side, in order to handle the different referencing schemes transparently for the COSEM client AP, the COSEM client application layer provides only one service set, using Logical Name referencing. This has two major consequences: • using a unique, standardized service set between COSEM client applications and the communications protocol – hiding the particularities of different COSEM servers – allows to specify an Application Programming Interface (API). This is an explicitly specified interface corresponding to this service set for applications running in a given computing environment (e.g. Windows XP, UNIX, etc.) Using this – public – API specification, client applications can be developed without knowledge about particularities of a given server; SIST EN 62056-53:2007

62056-53 © IEC:2006(E) – 15 – • when the COSEM server device does not use LN referencing, the client application layer shall include an additional component. The purpose of this component is to map the LN service set, used by the client AP into/from the service set, used by the server AP. Figure 6 shows the COSEM client application layer when the server is using SN referencing. The additional component is called SN_MAPPER_ASE. See also 6.5.5.2.
COSEM client ASO Client control function
COSEM client ASO services Referencing by Logical Name Supporting layer services Client xDLMS _ASE ClientACSECOSEM client application process COSEM client application layer COSEM server ASO COSEM server ASO services Supporting layer services Server xDLMS _ASE ServerACSECOSEM server application process COSEM server application layer Protocol Applications (communications) (interface objects) WAN, LAN
Client
SN_MAPPER Referencing by Short Name Server control functionSupporting layer
and
other protocol layers Supporting layer and
other protocol layers IEC
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Figure 6 – Structure of the COSEM AL when the server is using SN references 5.4 Layer management services Layer management services have local i
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