EN 61158-4-20:2014

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
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

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 - -
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
– 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
– 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.
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.
– 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.
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-user-entity DLSAP DLSAP DLSAP DLSAP-
addresses group DL-
address DLSAP-
address Ph-layer DL-layer DLS-users DLSAP-
address
NOTE 1 DLSAPs and PhSAPs are depicted as ovals spanning the boundary between two adjacent layers. NOTE 2 DL-addresses are depicted as designating small gaps (points of access) in the DLL portion of a DLSAP. NOTE 3 A single DL-entity may have multiple DLSAP-addresses and group DL-addresses associated with a single DLSAP. Figure 1 – Relationships of DLSAPs, DLSAP-addresses and group DL-addresses
3.3.3DL(SAP)-address either an individual DLSAP-address, designating a single DLSAP of a single DLS-user, or a group DL-address potentially designating multiple DLSAPs, each of a single DLS-user Note 1 to entry:
This terminology is chosen because ISO/IEC 7498-3 does not permit the use of the term DLSAP-address to designate more than a single DLSAP at a single DLS-user.
3.3.4(individual) DLSAP-address DL-address that designates only one DLSAP within the extended link Note 1 to entry:
A single DL-entity may have multiple DLSAP-addresses associated with a single DLSAP.
3.3.5extended link DL-subnetwork, consisting of the maximal set of links interconnected by DL-relays, sharing a single DL-name (DL-address) space, in which any of the connected DL-entities may communicate, one with another, either directly or with the assistance of one or more of those intervening DL-relay entities Note 1 to entry:
An extended link may be composed of just a single link.
3.3.6frame denigrated synonym for DLPDU SIST EN 61158-4-20:2015

– 12 – IEC 61158-4-20:2014 © IEC 2014
3.3.7group DL-address DL-address that potentially designates more than one DLSAP within the extended link Note 1 to entry:
A single DL-entity may have multiple group DL-addresses associated with a single DLSAP. A single DL-entity also may have a single group DL-address associated with more than one DLSAP.
3.3.8node single DL-entity as it appears on one local link
3.3.9receiving DLS-user DL-service user that acts as a recipient of DLS-user-data Note 1 to entry:
A DL-service user can be concurrently both a sending and receiving DLS-user.
3.3.10sending DLS-user DL-service user that acts as a source of DLS-user-data
Additional Type 20 definitions 3.4
3.4.1analog controller controller designed for use with only 4 mA to 20 mA current signaling that meets all requirements of a current input device or current output device
3.4.2analog signal low frequency current, predominantly 4 mA to 20 mA signal sent to or originating from a field device
3.4.3analog signal spectrum frequencies from zero to 25 Hz at unit amplitude and decreasing at 40 dB per decade above 25 Hz
3.4.4analog test filter two-pole low-pass Butterworth filter with the cutoff frequency of 25 Hz
3.4.5application function or data structure for which data is consumed or produced
3.4.6application object object class that manages and provides the run time exchange of messages across the network and within the network device Note 1 to entry:
Multiple types of application object classes may be defined.
3.4.7application relationship cooperative association between two or more application-entity-invocations for the purpose of exchange of information and coordination of their joint operation Note 1 to entry:
This relationship is activated either by the exchange of application-protocol-data-units or as a result of pre-configuration activities. SIST EN 61158-4-20:2015

IEC 61158-4-20:2014 © IEC 2014 – 13 –
3.4.8application relationship endpoint context and behaviour of an application relationship as seen and maintained by one of the application processes involved in the application relationship Note 1 to entry:
Each application process involved in the application relationship maintains its own application relationship endpoint.
3.4.9attribute description of an externally visible characteristic or feature of an object Note 1 to entry:
The attributes of an object contain information about variable portions of an object. Typically, they provide status information or govern the operation of an object. Attributes may also affect the behavior of an object. Attributes are divided into class attributes and instance attributes.
3.4.10barrier physical entity which limits current and voltage into a hazardous area in order to satisfy intrinsic safety requirements
3.4.11behavior indication of how the object responds to particular events
3.4.12broadcast process of sending a PDU to all devices that are connected to the network and are able to receive the transmission
3.4.13broadcast address address used by a master to send a command to all devices
3.4.14burst mode initiation of communication activity by a slave device at cyclic interval without request from a master
3.4.15cable capacitance per unit length capacitance per unit length of cable, measured at 1 kHz from one conductor other than the shield to all other conductors including the shield
Note 1 to entry: For networks comprised of more than one type or gauge of cable, the highest capacitance value of any cable type or gauge is used to determine this value.
3.4.16character The 8-bits of data and overhead bits that are transmitted as one continuous unit by the PhE
3.4.17character time amount of time required to transmit one character
3.4.18class set of objects, all of which represent the same kind of system component SIST EN 61158-4-20:2015

– 14 – IEC 61158-4-20:2014 © IEC 2014 Note 1 to entry:
A class is a generalization of the object; a template for defining variables and methods. All objects in a class are identical in form and behavior, but usually contain different data in their attributes.
3.4.19class attributes attribute that is shared by all objects within the same class
3.4.20class code unique identifier assigned to each object class
3.4.21class specific service service defined by a particular object class to perform a required function which is not performed by a common service Note 1 to entry:
A class specific object is unique to the object class which defines it.
3.4.22client a) object which uses the services of another (server) object to perform a task b) initiator of a message to which a server reacts, such as the role of an AR endpoint in which it issues confirmed service request APDUs to a single AR endpoint acting as a server
3.4.23comm error detectable error in receiving a PhPDU or DLPDU, also ‘Communication error code’ octet of APDU
3.4.24conveyance path unidirectional flow of APDUs across an application relationship
3.4.25current sense resistor resistor that is used to convert analog current signal into a voltage signal
3.4.26cyclic term used to describe events which repeat in a regular and repetitive manner
3.4.27delay distortion difference in propagation time delays of sine waves of different frequencies when observing the time delay through a network or circuit
3.4.28device any entity containing an implementation of this standard
3.4.29device ID serial number for a device that is unique among all instances of one type of device Note 1 to entry:
The manufacturer is required to assigned unique value for every device that has the identical values for Manufacturer ID and Device Type. SIST EN 61158-4-20:2015

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3.4.30device type manufacturer’s type of a device, e.g. its product name Note 1 to entry:
The value of this attribute is assigned by the manufacturer. Its value specifies the set of commands and data objects supported by the device. The manufacturer is required to assigned unique value to each type of the device.
3.4.31device variable uniquely defined data item within a Field Device that is always associated with process-related information Note 1 to entry:
A device variable's value varies in response to changes and variations in the process to which the device is connected.
3.4.32digital signal communication of information using the 1 200 bits per second frequency shift keying signal
3.4.33digital frequency band range of frequencies from 950 Hz to 2 500 Hz that is used for digital signal
3.4.34digital signal spectrum frequencies from 500 Hz to 10 kHz at unit amplitude, decreasing at 40 dB per decade below 500 Hz and decreasing at 20 dB per decade above 10 kHz
3.4.35dynamic variable a device variable that is assigned as the dynamic variable and possibly associated with an analog channel Note 1 to entry:
A device may contain up to four variables – primary, secondary, tertiary and quaternary. These are collectively called the dynamic variables.
3.4.36endpoint one of the communicating entities involved in a connection
3.4.37error discrepancy between a computed, observed or measured value or condition and the specified or theoretically correct value or condition
3.4.38error code identification of a specific type of error within an error class
3.4.39expanded device type manufacturer’s type of a device as specified in IEC 61158-6-20, Table 6
3.4.40extended frequency band range of frequencies from 500 Hz to 10 kHz Note 1 to entry: This frequency band is digital frequency band plus guard band. SIST EN 61158-4-20:2015

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3.4.41field device physical entity that is connected to the process or to plant equipment and has at least one signalling element that communicates with other signalling element(s) via a cable Note 1 to entry:
It directly connects to the sensor or actuator or performs process control function and it is directly connected to the physical layer specified in this standard. It may generate or receive an analog signal in addition to a digital signal.
3.4.42frame format of aggregated bits that are transmitted together in time
3.4.43ground surface of the earth or the conduits or pipes that are so connected, or the safety bus bar or the zero volt rail to which the barriers are connected Note 1 to entry: Ground may or may not be the same as network power supply common.
3.4.44intrinsic safety design methodology for a circuit or an assembly of circuits in which any spark or thermal effect produced under normal operating and specified fault conditions is not capable under prescribed test conditions of causing ignition of a given explosive atmosphere
3.4.45junction any splice of two cables or any attachment point of another cable or of a field device to an existing cable
3.4.46long_tag 32 characters restricted ISO Latin-1 string used to identify a field device
3.4.47loop current value measured by a mA in series with the field device Note 1 to entry:
The loop current is a near DC analog 4 mA to 20 mA signal used to communicate a single value between the control system and the field device. Voltage mode devices use "Volts DC" as their engineering units where "loop current" values are used.
3.4.48management information network-accessible information that supports managing the operation of the fieldbus system, including the application layer Note 1 to entry:
Managing includes functions such as controlling, monitoring, and diagnosing.
3.4.49manufacturer ID 2 octet enumeration identifying the manufacturer that produced a device Note 1 to entry:
A manufacturer is required to use the value assigned to it and is not permitted to use the value assigned to another manufacturer.
3.4.50master device that initiates communication activity by sending request frame to another device and expecting a response frame from that device SIST EN 61158-4-20:2015

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3.4.51message information-bearing part, except the preamble part of the frame
3.4.52multi-drop network network with more than one slave device connected to one network
3.4.53network a single pair of cable, connectors, associated signaling elements by which a given set of signaling devices are interconnected and non-signaling elements that are attached to the same pair of cable Note 1 to entry: An installation using multiple-pair wire and a common network power supply is considered as multiple networks.
3.4.54network power supply source that supplies operating power directly to a network
3.4.55network resistance resistance or real part of the impedance of a network Note 1 to entry: It is computed as the equivalent impedance of all devices connected in parallel to the network. Therefore it is usually dominated by one low impedance device.
3.4.56non-signaling element physical entity or an element that does not use or produce analog signal or digital signal Note 1 to entry: A network power supply is an example of non-signaling element.
3.4.57payload data contents of a data message that is being transmitted
3.4.58point-to-point network network with only one slave and zero or one master device Note 1 to entry: The point-to-point Network need not have any master device. This situation would exist, for example, when only an analog controller is used, the single field device having been programmed by a secondary master that was subsequently disconnected.
3.4.59polling address identifier assigned to a device such that it is unique within the network to which the device is connected
3.4.60primary master master device that can always initiate the communication
3.4.61secondary master master device that can initiate the communication only through an arbitration process and when primary master has relinquished the initiation of the communication SIST EN 61158-4-20:2015

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3.4.62server role of an AREP in which it returns a confirmed service response APDU to the client that initiated the request
3.4.63signaling element physical entity or an element that uses or produces digital signal
3.4.64silence state of the network when there is no digital signal is present
3.4.65slave device that initiates communication activity only after it receives a request frame from a master device and is required to send a response to that request
3.4.66start of message The preamble of physical layer PDU followed by the delimiter of data link layer PDU without any reception error and inter-character gap
3.4.67tag 8-character ASCII string used to identify a field device
3.4.68transaction exchange of related, consecutive frames between two peer medium access control entities, required for a successful transmission Note 1 to entry:
A transaction consists of either (a) a single PhPDU transmission from a source device, or (b) one PhPDU from the source device followed by a second, link-level acknowledgement PhPDU from the destination device.
3.4.69unique ID identifier assigned to a device which is unique among all instances of the devices compliant to this standard
Common symbols and abbreviations 3.5NOTE Many symbols and abbreviations are common to more than one protocol Type; they are not necessarily used by all protocol Types.
Data units 3.5.13.5.1.1 DLPDU DL-protocol data unit 3.5.1.2 DLSDU DL-service data unit 3.5.1.3 PhIDU Ph-interface data unit 3.5.1.4 PhPDU Ph-protocol data unit
Miscellaneous 3.5.23.5.2.1 DL- data link layer (as a prefix) SIST EN 61158-4-20:2015

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