IEC 61158-3-19:2019

IEC 61158-3-19 ®
Edition 4.0 2019-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Industrial communication networks – Fieldbus specifications –
Part 3-19: Data-link layer service definition – Type 19 elements

Réseaux de communication industriels – Spécifications des bus de terrain –
Partie 3-19: Définition des services de couche liaison de données – Éléments
de type 19
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IEC 61158-3-19 ®
Edition 4.0 2019-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Industrial communication networks – Fieldbus specifications –

Part 3-19: Data-link layer service definition – Type 19 elements

Réseaux de communication industriels – Spécifications des bus de terrain –

Partie 3-19: Définition des services de couche liaison de données – Éléments

de type 19
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 25.040.40; 35.100.20; 35.110 ISBN 978-2-8322-9113-9

– 2 – IEC 61158-3-19:2019 © IEC 2019
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
1.1 General . 7
1.2 Specifications . 7
1.3 Conformance . 7
2 Normative references . 8
3 Terms, definitions, symbols, abbreviations and conventions . 8
3.1 Reference model terms and definitions . 8
3.2 Service convention terms and definitions . 10
3.3 Data-link service terms and definitions . 11
3.4 Symbols and abbreviations . 13
3.5 Common conventions . 14
4 Data-link services and concepts . 16
4.1 Overview. 16
4.1.1 General . 16
4.1.2 Acknowledged connection oriented data transfer: Read (RD) . 17
4.1.3 Acknowledged connection oriented data transfer: Read (WR) . 17
4.1.4 Acknowledged connection oriented data transfer:
Initiate_cyclic_communication (ICC) . 18
4.1.5 Acknowledged connection oriented data transfer:
Disable_cyclic_communication (DCC) . 18
4.1.6 Unacknowledged connectionless data transfer: Write_cyclic (WRC) . 18
4.1.7 Unacknowledged connectionless data transfer: Send_Device_Status
(SDS) . 18
4.1.8 Unacknowledged connectionless data transfer: Write_Device_Status
(WDS) . 18
4.2 Service channel services (SVC services) . 18
4.2.1 General . 18
4.2.2 Read (RD) . 18
4.2.3 Write (WR). 19
4.3 Hot-plug services . 20
4.3.1 Enable_Hotplug (EHP) . 20
4.3.2 Notify_Hotplug (NHP) . 21
4.4 Realtime channel setup services (RTCS services) . 21
4.4.1 General . 21
4.4.2 Initiate_cyclic_communication (ICC) . 21
4.4.3 Disable_cyclic_communication (DCC) . 22
4.5 RTC services . 23
4.5.1 General . 23
4.5.2 Notify_Error (NER) . 23
4.5.3 Write_cyclic (WRC) . 23
4.5.4 Send_Device_Status (SDS) . 24
4.5.5 Write_Device_Status (WDS) . 25
4.5.6 Notify_Network_Status_Change (NNSC) . 25
Bibliography . 26

Figure 1 – Relationships of DLSAPs, DLSAP-addresses and group DL-addresses . 16

Table 1 – Summary of DL services and primitives . 17
Table 2 – Read (RD) . 19
Table 3 – Write (WR) . 20
Table 4 – Enable_Hotplug (EHP) . 21
Table 5 – Notify_Hotplug (NHP) . 21
Table 6 – Initiate_cyclic_communication (ICC) . 22
Table 7 – Disable_cyclic_communication (DCC) . 23
Table 8 – Notify_Error (NER) . 23
Table 9 – Write_cyclic (WRC) . 24
Table 10 – Send_Device_Status (SDS) . 24
Table 11 – Write_Device_Status (WDS) . 25
Table 12 – Notify_Network_Status_Change (NNSC) . 25

– 4 – IEC 61158-3-19:2019 © IEC 2019
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INDUSTRIAL COMMUNICATION NETWORKS –
FIELDBUS SPECIFICATIONS –
Part 3-19: Data-link layer service definition –
Type 19 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
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5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
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6) All users should ensure that they have the latest edition of this publication.
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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 61158-3-19 has been prepared by subcommittee 65C: Industrial
networks, of IEC technical committee 65: Industrial-process measurement, control and
automation.
This fourth edition cancels and replaces the third edition published in 2014.This edition
constitutes a technical revision.

This edition includes the following significant technical changes with respect to the previous
edition:
• improving the hotplug and redundancy features;
• improving the phase switching and the error handling;
• editorial improvements.
The text of this International Standard is based on the following documents:
FDIS Report on voting
65C/945/FDIS 65C/954/RVD
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
This publication has been drafted in accordance with 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.
– 6 – IEC 61158-3-19:2019 © IEC 2019
INTRODUCTION
This document 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.
Throughout the set of fieldbus standards, the term “service” refers to the abstract capability
provided by one layer of the OSI Basic Reference Model to the layer immediately above.
Thus, the data-link layer service defined in this document is a conceptual architectural
service, independent of administrative and implementation divisions.

INDUSTRIAL COMMUNICATION NETWORKS –
FIELDBUS SPECIFICATIONS –
Part 3-19: Data-link layer service definition –
Type 19 elements
1 Scope
1.1 General
This part of IEC 61158 provides common elements for basic time-critical messaging
communications between devices in an automation environment. The term “time-critical” is
used to represent the presence of a time-window, within which one or more specified actions
are required to be completed with some defined level of certainty. Failure to complete
specified actions within the time window risks failure of the applications requesting the
actions, with attendant risk to equipment, plant and possibly human life.
This International Standard defines in an abstract way the externally visible service provided
by the Type 19 fieldbus data-link layer in terms of
a) the primitive actions and events of the service;
b) the parameters associated with each primitive action and event, and the form which they
take; and
c) the interrelationship between these actions and events, and their valid sequences.
The purpose of this document is to define the services provided to
• the Type 19 fieldbus application layer at the boundary between the application and data-
link layers of the fieldbus reference model, and
• systems management at the boundary between the data-link layer and systems
management of the fieldbus reference model.
1.2 Specifications
The principal objective of this document is to specify the characteristics of conceptual data-
link layer services suitable for time-critical communications, and thus supplement the OSI
Basic Reference Model in guiding the development of data-link protocols for time-critical
communications. A secondary objective is to provide migration paths from previously-existing
industrial communications protocols.
This document may be used as the basis for formal DL-Programming-Interfaces.
Nevertheless, it is not a formal programming interface, and any such interface will need to
address implementation issues not covered by this specification, including:
a) the sizes and octet ordering of various multi-octet service parameters, and
b) the correlation of paired request and confirm, or indication and response, primitives.
1.3 Conformance
This document does not specify individual implementations or products, nor do they constrain
the implementations of data-link entities within industrial automation systems.
There is no conformance of equipment to this data-link layer service definition standard.
Instead, conformance is achieved through implementation of the corresponding data-link
protocol that fulfils the Type 19 data-link layer services defined in this document.

– 8 – IEC 61158-3-19:2019 © IEC 2019
2 Normative references
The following documents are referred to in the text in such a way that some or all of their
content constitutes requirements 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 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.
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, abbreviations and conventions
For the purposes of this document, the following terms, definitions, symbols, abbreviations
and conventions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1 Reference model terms and definitions
This document 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 DL-address [7498-3]
3.1.2 DL-address-mapping
[7498-1]
3.1.3 called-DL-address [7498-3]
3.1.4 calling-DL-address
[7498-3]
3.1.5 centralized multi-end-point-connection [7498-1]
3.1.6 DL-connection
[7498-1]
3.1.7 DL-connection-end-point [7498-1]
3.1.8 DL-connection-end-point-identifier
[7498-1]
3.1.9 DL-connection-mode transmission [7498-1]
3.1.10 DL-connectionless-mode transmission
[7498-1]
3.1.11 correspondent (N)-entities [7498-1]
correspondent DL-entities  (N=2)
correspondent Ph-entities  (N=1)
3.1.12 DL-duplex-transmission [7498-1]
3.1.13 (N)-entity [7498-1]
DL-entity  (N=2)
Ph-entity  (N=1)
3.1.14 DL-facility
[7498-1]
3.1.15 flow control [7498-1]
3.1.16 (N)-layer [7498-1]
DL-layer  (N=2)
Ph-layer  (N=1)
3.1.17 layer-management [7498-1]
3.1.18 DL-local-view [7498-3]
3.1.19 DL-name [7498-3]
3.1.20 naming-(addressing)-domain
[7498-3]
3.1.21 peer-entities [7498-1]
3.1.22 primitive name
[7498-3]
3.1.23 DL-protocol [7498-1]
3.1.24 DL-protocol-connection-identifier [7498-1]
3.1.25 DL-protocol-data-unit [7498-1]
3.1.26 DL-relay
[7498-1]
3.1.27 reset [7498-1]
3.1.28 responding-DL-address
[7498-3]
3.1.29 routing [7498-1]
3.1.30 segmenting
[7498-1]
– 10 – IEC 61158-3-19:2019 © IEC 2019
3.1.31 (N)-service [7498-1]
DL-service  (N=2)
Ph-service  (N=1)
3.1.32 (N)-service-access-point
[7498-1]
DL-service-access-point  (N=2)
Ph-service-access-point  (N=1)
3.1.33 DL-service-access-point-address [7498-3]
3.1.34 DL-service-connection-identifier
[7498-1]
3.1.35 DL-service-data-unit [7498-1]
3.1.36 DL-simplex-transmission
[7498-1]
3.1.37 DL-subsystem [7498-1]
3.1.38 systems-management
[7498-1]
3.1.39 DL-user-data [7498-1]
3.2 Service convention terms and definitions
This document 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
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 DL-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
3.3 Data-link service terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.3.1
communication cycle
fixed time period between two master synchronization telegrams in which real-time telegrams
are transmitted in the RT channel and non real-time telegrams are transmitted in the IP
channel
3.3.2
cycle time
duration of a communication cycle
3.3.3
cyclic communication
periodic exchange of telegrams
3.3.4
cyclic data
part of a telegram, which does not change its meaning during cyclic operation of the network

– 12 – IEC 61158-3-19:2019 © IEC 2019
3.3.5
device
a slave in the communication network, (e.g., a power drive system as defined in the
IEC 61800, I/O stations as defined in the IEC 61131)
3.3.6
device status
four adjacent octets inside the acknowledge telegram containing status information for each
device
3.3.7
DL-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
3.3.8
DLSAP
distinctive point at which DL-services are provided by a single DL-entity to a single higher-
layer entity
Note 1 to entry: Definition derived from ISO/IEC 7498-1:1994, Clause 5.
3.3.9
DL(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.
3.3.10
(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.
3.3.11
element
part of IDNs – each IDN has 7 elements, whereas each one has a specific meaning (e.g.,
number, name, data)
3.3.12
extended 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.
3.3.13
frame
denigrated synonym for DLPDU
3.3.14
group 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.
3.3.15
identification number
IDN
designation of operating data under which a data block is preserved with its attribute, name,
unit, minimum and maximum input values, and the data
3.3.16
master
node, which assigns the other nodes (i.e., slaves) the right to transmit
3.3.17
node
single DL-entity as it appears on one local link
3.3.18
protocol
convention about the data formats, time sequences, and error correction in the data exchange
of communication systems
3.3.19
receiving DLS-user
DL-service user that acts as a recipient of DL-user-data
Note 1 to entry: A DL-service user can be concurrently both a sending and receiving DLS-user.
3.3.20
sending DLS-user
DL-service user that acts as a source of DL-user-data
3.3.21
service channel
SVC
non-real-time transmission of information upon master request during RT channel
3.3.22
slave
node, which is assigned the right to transmit by the master
3.3.23
topology
physical network architecture with respect to the connection between the stations of the
communication system
3.4 Symbols and abbreviations
AT Acknowledge telegram
CA Procedure command acknowledgment
CC Cross communication between participants
DA Destination address
DAT Duration of acknowledge telegram
DL- Data-link layer (as a prefix)

– 14 – IEC 61158-3-19:2019 © IEC 2019
DLC DL-connection
DLCEP DL-connection-end-point
DLE DL-entity (the local active instance of the data-link layer)
DLL DL-layer
DLPCI DL-protocol-control-information
DLPDU DL-protocol-data-unit
DLM DL-management
DLME DL-management entity (the local active instance of DL-management)
DLMS DL-management service
DLS DL-service
DLSAP DL-service-access-point
DLSDU DL-service-data-unit
FIFO First-in first-out (queuing method)
HS service channel handshake (see AHS and MHS)
IDN Identification number
INFO service channel information
MC motion control or motion controller (see also NC)
NC numerical control (also control unit or controller)
OSI Open systems interconnection
Ph- Physical layer (as a prefix)
PhE Ph-entity (the local active instance of the physical layer)
PhL Ph-layer
QoS Quality of service
RE Resource element
RT real-time
RTC real-time channel
SA source address
SI Sub Index
SVC Service Channel
XX address of a device
3.5 Common conventions
This document uses the descriptive conventions given in ISO/IEC 10731.
The service model, service primitives, and time-sequence diagrams used are entirely abstract
descriptions; they do not represent a specification for implementation.
Service primitives, used to represent service user/service provider interactions (see
ISO/IEC 10731), convey parameters that indicate information available in the user/provider
interaction.
This document uses a tabular format to describe the component parameters of the DLS
primitives. The parameters that apply to each group of DLS primitives are set out in tables
throughout the remainder of this document. Each table consists of up to six columns,
containing the name of the service parameter, and a column each for those primitives and
parameter-transfer directions used by the DLS:
– the request primitive’s input parameters;

– the request primitive’s output parameters;
– the indication primitive’s output parameters;
– the response primitive’s input parameters; and
– the confirm primitive’s output parameters.
NOTE The request, indication, response and confirm primitives are also known as requestor.submit,
acceptor.deliver, acceptor.submit, and requestor.deliver primitives, respectively (see ISO/IEC 10731).
One parameter (or part of it) is listed in each row of each table. Under the appropriate service
primitive columns, a code is used to specify the type of usage of the parameter on the
primitive and parameter direction specified in the column:
M – parameter is mandatory for the primitive.
U – parameter is a User option, and may or may not be provided depending on
the dynamic usage of the DLS-user. When not provided, a default value for
the parameter is assumed.
C – parameter is conditional upon other parameters or upon the environment of
the DLS-user.
(blank) – parameter is never present.
Some entries are further qualified by items in brackets. These may be
a) a parameter-specific constraint
(=) indicates that the parameter is semantically equivalent to the parameter in the
service primitive to its immediate left in the table;
b) an indication that some note applies to the entry
(n) indicates that the following note n contains additional information pertaining to the
parameter and its use.
In any particular interface, not all parameters need be explicitly stated. Some may be
implicitly associated with the DLSAP at which the primitive is issued.
Figure 1 shows the relationships of DLSAPs, DLSAP-addresses and group DL-addresses.

– 16 – IEC 61158-3-19:2019 © IEC 2019

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 can have multiple DLSAP-addresses and group DL-addresses associated with a single
DLSAP.
Figure 1 – Relationships of DLSAPs, DLSAP-addresses and group DL-addresses
In the diagrams which illustrate these interfaces, dashed lines indicate cause-and-effect or
time-sequence relationships, and wavy lines indicate that events are roughly
contemporaneous.
4 Data-link services and concepts
4.1 Overview
4.1.1 General
The data-link layer specifies Type 19 services for reading and writing data from devices in a
Type 19 network (see Table 1). The mechanisms for using these services are related to the
Type 19 specific Identification Numbers (IDN). There are four different types of services:
• Service channel services (confirmed, non-cyclic),
• Hot-Plug services (confirmed and unconfirmed, non-cyclic),
• Real-time channel setup services (confirmed, non-cyclic),
• Real-time services (unconfirmed, cyclic).

Table 1 – Summary of DL services and primitives
Service Primitive Possible for these station classes
Acknowledged connection oriented data transfer: DL-RD request Master
Read (RD) DL-RD confirm
DL-RD indication Slave
DL-RD response
Acknowledged connection oriented data transfer: DL-WR request Master
Read (WR) DL-WR confirm
DL-WR indication Slave
DL-WR response
Acknowledged connection oriented data transfer: DL-ICC request Master
Initiate_cyclic_communication (ICC) DL-ICC confirm
DL-ICC indication Slave
DL-ICC response
Acknowledged connection oriented data transfer: DL-DCC request Master
Disable_cyclic_communication (DCC) DL-DCC confirm
DL-DCC indication Slave
DL-DCC response
Unacknowledged connectionless data transfer: DL-WRC request Master or Slave
Write_cyclic (WRC) DL-WRC confirm
DL-WRC indication Slave or Master
Unacknowledged connectionless data transfer: DL-SDS request Slave
Send_device_status (SDS) DL-SDS confirm
DL-SDS indication Master
Unacknowledged connectionless data transfer: DL-WDS request Master
Write_device_status (WDS) DL-WDS confirm
DL-WDS indication Slave
4.1.2 Acknowledged connection oriented data transfer: Read (RD)
This service permits the local DLS-user to send a DLSDU to a single remote station. At the
remote station, the DLSDU, if the respective DLPDU is transferred error-free, is delivered by
the remote DLE to its local DLS-user and answered by it. This response is send back. The
originating local DLS-user receives a confirmation answer of the DLSDU by the remote DLS-
user. If an error occurred during the transfer, the originating DLE repeats the data transfer up
to a configured maximum number of times.
4.1.3 Acknowledged connection oriented data transfer: Read (WR)
This service permits the local DLS-user to send a DLSDU to a single remote station. At the
remote station, the DLSDU, if the respective DLPDU is transferred error-free, is delivered by
the remote DLE to its local DLS-user and answered by it. This response is send back. The
originating local DLS-user receives a confirmation answer of the DLSDU by the remote DLS-
user. If an error occurred during the transfer, the originating DLE repeats the data transfer up
to a configured maximum number of times.

– 18 – IEC 61158-3-19:2019 © IEC 2019
4.1.4 Acknowledged connection oriented data transfer:
Initiate_cyclic_communication (ICC)
This service permits the local DLS-user to send a DLSDU to a several remote station. At the
remote station, the DLSDU, if the respective DLPDU is transferred error-free, is delivered by
the remote DLE to its local DLS-user and answered by it. This response is send back. The
originating local DLS-user receives a confirmation answer of the DLSDU by the remote DLS-
user. If an error occurred during the transfer, the originating DLE repeats the data transfer up
to a configured maximum number of times.
4.1.5 Acknowledged connection oriented data transfer:
Disable_cyclic_communication (DCC)
This service permits the local DLS-user to send a DLSDU to remote stations. At the remote
station, the DLSDU, if the respective DLPDU is transferred error-free, is delivered by the
remote DLE to its local DLS-user and answered by it. This response is send back. The
originating local DLS-user receives a confirmation answer of the DLSDU by the remote DLS-
user. If an error occurred during the transfer, the originating DLE repeats the data transfer up
to a configured maximum number of times.
4.1.6 Unacknowledged connectionless data transfer: Write_cyclic (WRC)
This service permits a local DLS-user to transfer a DLSDU to a single remote station or a list
of stations. The local DLS-user receives a confirmation acknowledging the completion of the
transfer, but not whether the DLPDU was duly received. At each addressed remote station
this DLSDU, if the respective DLPDU is received error-free, is delivered to a single local DLS-
user. There is no confirmation to the sending DLS-user that such an intended delivery has
taken place.
4.1.7 Unacknowledged connectionless data transfer: Send_Device_Status (SDS)
This service permits a local DLS-user to transfer a DLSDU to a single remote station. The
local DLS-user receives a confirmation acknowledging the completion of the transfer, but not
whether the DLPDU was duly received. At the addressed remote station, this DLSDU, if the
respective DLPDU is received error-free, is delivered to a single local DLS-user. There is no
confirmation to the sending DLS-user that such an intended delivery has taken place.
4.1.8 Unacknowledged connectionless data transfer: Write_Device_Status (WDS)
This service permits a local DLS-user to transfer a DLSDU to a single remote station. The
local DLS-user receives a confirmation acknowledging the completion of the transfer, but not
whether the DLPDU was duly received. At the addressed remote station, this DLSDU, if the
respective DLPDU is received error-free, is delivered to a single local DLS-user. There is no
confirmation to the sending DLS-user that such an intended delivery has taken place.
4.2 Service channel services (SVC services)
4.2.1 General
With the services of the service channel, a master reads or writes elements of an IDN of a
slave device.
4.2.2 Read (RD)
4.2.2.1 Function
With the RD service, a master reads elements of an IDN from one selected slave device
(see Table 2).
Table 2 – Read (RD)
Request Indication Response Confirmation
Parameter name input output input output
Device address M M (=)
IDN M M (=)
Element M M (=)
Data  M M (=)
Error code  M M (=)
NOTE The method by which a confirm primitive is correlated with its corresponding preceding
request primitive is a local matter. The method by which a response primitive is correlated with
its corresponding preceding indication primitive is a local matter. See 1.2.

4.2.2.2 Request and Indication parameters
4.2.2.2.1 Device address
This parameter is used to address the device from which the data is to be read.
4.2.2.2.2 IDN
This parameter is used to identify the IDN from which the data is to be read.
4.2.2.2.3 Element
This parameter is used to identify the element of the IDN that is to be read. The element
consists of a data block element that is mandatory, a structure instance (SI) that is conditional
on the IDN and a structure element (SE) that is also conditional on the IDN. The structure
instance is used to address a specific function group instance, whereas the structure element
is used as an additional address which is related to a specific function group element.
4.2.2.3 Response and confirmation parameters
4.2.2.3.1 General
The result conveys the service specific parameters of the service response.
4.2.2.3.2 Data
This parameter specifies the data which was read from the device.
4.2.2.3.3 Error code
This parameter specifies the error code of the read request.
4.2.3 Write (WR)
4.2.3.1 Function
With the Write services a master writes elements of an IDN to one selected slave device (see
Table 3).
– 20 – IEC 61158-3-19:2019 © IEC 2019
Table 3 – Write (WR)
Request Indication Response Confirmation
Parameter name input output input output
Device Address M M (=)
IDN M M (=)
Element M M (=)
Data M M (=)
Error Code  M M (=)
NOTE The method by which a confirm primitive is correlated with its corresponding preceding
request primitive is a local matter. The method by which a response primitive is correlated with
its corresponding preceding indication primitive is a local matter. See 1.2.

4.2.3.2 Request and Indication parameters
4.2.3.2.1 Device address
This parameter is used to address the device to which the data is to be written.
4.2.3.2.2 IDN
This parameter is used to identify the IDN from which the data is to be written.
4.2.3.2.3 Element
This parameter is used to identify the element of the IDN that is to be written. The element
consists of a data block element that is mandatory, a structure instance (SI) that is conditional
on the IDN and a structure element (SE) that is also conditional on the IDN. The structure
instance is used to address a specific function group instance, whereas the structure element
is used as an additional address which is related to a specific function group element.
4.2.3.2.4 Data
This parameter specifies the data which is written to the device.
4.2.3.3 Response and confi
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