IEC 61158-3-28:2023

IEC 61158-3-28 ®
Edition 1.0 2023-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Industrial communication networks – Fieldbus specifications –
Part 3-28: Data-link layer service definition – Type 28 elements

Réseaux de communication industriels – Spécifications des bus de terrain –
Partie 3 28: Définition des services de la couche liaison de données – Éléments
de type 28
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IEC 61158-3-28 ®
Edition 1.0 2023-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Industrial communication networks – Fieldbus specifications –

Part 3-28: Data-link layer service definition – Type 28 elements

Réseaux de communication industriels – Spécifications des bus de terrain –

Partie 3 28: Définition des services de la couche liaison de données – Éléments

de type 28
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 25.040 ISBN 978-2-8322-6573-4

– 2 – IEC 61158-3-28:2023 © IEC 2023
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
1.1 General . 8
1.2 Specifications . 8
1.3 Conformance . 8
2 Normative references. 9
3 Terms, definitions, abbreviated terms and conventions . 9
3.1 Reference model terms and definitions . 9
3.2 Service convention terms and definitions . 11
3.3 Common data-link service terms and definitions . 11
3.4 Additional Type 28 data-link specific definitions . 13
3.5 Common symbols and abbreviations . 15
3.6 Additional Type 28 symbols and abbreviations . 15
4 Type 28 Data-link service . 16
4.1 Overview. 16
4.2 Model of the DLS . 17
4.2.1 General . 17
4.2.2 Connection-less mode data transmission with acknowledge (CLMDTA) . 17
4.2.3 Connection-less mode data transmission with no acknowledge
(CLMDTNA) . 17
4.2.4 Connection-less mode data transmission with request and acknowledge
(CLMDTRA) . 17
4.2.5 Connection-less mode data transmission with request and response but
no acknowledge (CLMDTRRNA) . 18
4.2.6 Connection mode data transmission with acknowledge (CMDTA) . 18
4.2.7 Connection mode data transmission with no acknowledge (CMDTNA) . 18
4.3 Detailed description of DLS . 18
4.3.1 CLMDTA . 18
4.3.2 CLMDTNA . 20
4.3.3 CLMDTRA . 22
4.3.4 CLMDTRRNA . 25
4.3.5 CMDTA . 27
4.3.6 CMDTNA . 29
4.4 Detailed description of DLCSS. 30
4.4.1 General . 30
4.4.2 Delay measurement . 31
4.4.3 Clock synchronization . 33
4.4.4 Clock interrupt . 35
5 Type 28 Data-link management service . 36
5.1 Overview. 36
5.2 DLMS related information table . 36
5.2.1 General . 36
5.2.2 Protocol stack version management Information table . 37
5.2.3 Link node management Information table . 37
5.2.4 Link timeout management information table . 38
5.3 Detailed description of DLMS . 40

5.3.1 General . 40
5.3.2 Config . 40
5.3.3 Discovery . 45
5.3.4 Maintenance . 47
5.3.5 Establish . 51
5.3.6 Release . 53
5.3.7 Update . 54
Bibliography . 57

Figure 1 – Relationships of DLSAPs, DLSAP-addresses and group DL-addresses . 12
Figure 2 – Bitmap Data type diagram . 15
Figure 3 – Primitive process of CLMDTA . 19
Figure 4 – Primitive process of CLMDTNA . 21
Figure 5 – Primitive process of CLMDTRA . 23
Figure 6 – Primitive process of CLMDTRRNA . 25
Figure 7 – Primitive process of CMDTA . 27
Figure 8 – Primitive process of CMDTNA . 29
Figure 9 – Delay measurement service primitive process . 31
Figure 10 – Clock synchronization service primitive process . 33
Figure 11 – Clock interrupt service primitive process . 35
Figure 12 – Data-link config management service primitive process . 41
Figure 13 – TN active logout discovery service primitive process . 45
Figure 14 – Data-link discovery management service primitive process . 45
Figure 15 – Local data-link maintenance service primitive process . 48
Figure 16 – Remote data-link maintenance service primitive process . 48
Figure 17 – Data-link establish management service primitive process . 51
Figure 18 – Data-link release management service primitive sequence diagram . 53
Figure 19 – Data-link update management service primitive sequence diagram . 55

Table 1 – DTS status output value . 16
Table 2 – DLCSS status return value . 17
Table 3 – CLMDTA service primitives and parameters . 20
Table 4 – CLMDTA service primitive parameter . 20
Table 5 – CLMDTNA service primitives and parameters . 22
Table 6 – CLMDTNA service primitive parameter . 22
Table 7 – CLMDTRA service primitives and parameters . 24
Table 8 – CLMDTRA service primitive parameter . 24
Table 9 – CLMDTRRNA service primitives and parameters . 26
Table 10 – CLMDTRRNA service primitive parameter . 26
Table 11 – CMDTA service primitives and parameters . 28
Table 12 – CMDTA service primitive parameter . 28
Table 13 – CMDTNA service primitives and parameters . 30
Table 14 – CMDTNA service primitive parameter . 30
Table 15 – Delay measurement service primitives and parameters . 32

– 4 – IEC 61158-3-28:2023 © IEC 2023
Table 16 – Delay measurement service primitive parameter . 32
Table 17 – Clock synchronization service primitives and parameters . 34
Table 18 – Clock synchronization service primitive parameter . 34
Table 19 – Clock interrupt service primitives and parameters . 35
Table 20 – Clock interrupt service primitive parameter . 36
Table 21 – Protocol stack version management Information table . 37
Table 22 – Link node management Information table . 37
Table 23 – Link timeout management information table . 39
Table 24 – DLMS status return value . 40
Table 25 – Data-link config management service . 41
Table 26 – Data-link config management service primitive parameter . 41
Table 27 – CFG_PARAM_INFO structure . 42
Table 28 – TIMEOUT_CFG structure . 43
Table 29 – GROUP_IDMAP_S structure . 43
Table 30 – NODEID_MAC_S structure . 44
Table 31 – COMM_RES_CFG structure . 44
Table 32 – Data-link discovery service primitives and parameters . 46
Table 33 – Data-link discovery management service primitive parameter . 46
Table 34 – NODE_MGT_INFO_S structure . 47
Table 35 – Data-link maintenance service primitives and parameters . 49
Table 36 – Data-link maintenance service primitive parameter . 49
Table 37 – DIAG_INFO_S structure (Command in range from 0x00 to 0x05) . 50
Table 38 – DIAG_INFO_S structure (Command = 0x06) . 50
Table 39 – Data-link establish management service primitives and parameters . 52
Table 40 – Data-link establish management service parameter . 52
Table 41 – CH_RES_INFO_S structure . 52
Table 42 – Data-link release management service primitives and parameters . 54
Table 43 – Data-link release management service primitive parameter . 54
Table 44 – Data-link update management service primitives and parameters . 56
Table 45 – Data-link update management service primitive parameter . 56

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INDUSTRIAL COMMUNICATION NETWORKS –
FIELDBUS SPECIFICATIONS –
Part 3-28: Data-link layer service definition –
Type 28 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
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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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
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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 the IEC 61784-1 series and the IEC 61784-2 series.
IEC 61158-3-28 has been prepared by subcommittee 65C: Industrial networks, of IEC technical
committee 65: Industrial-process measurement, control and automation. It is an International
Standard.
– 6 – IEC 61158-3-28:2023 © IEC 2023
The text of this International Standard is based on the following documents:
Draft Report on voting
65C/1206/FDIS 65C/1235/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
A list of all the parts of the IEC 61158 series, 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 document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The "colour inside" logo on the cover page of this document 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.

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.

– 8 – IEC 61158-3-28:2023 © IEC 2023
INDUSTRIAL COMMUNICATION NETWORKS –
FIELDBUS SPECIFICATIONS –
Part 3-28: Data-link layer service definition –
Type 28 elements
1 Scope
1.1 General
This part of IEC 61158 describes basic packet communication services and models in an
automation control industrial field environment. The Type 28 data-link layer provides time-
critical and non-time-critical communication services. Time-critical refers to the requirement to
complete specified functions between devices in a defined time window in an industrial field
environment. Failure to complete specified functions within the time window can lead to failure
or harm in industrial production.
This document defines in an abstract way the externally visible service provided by the Type
28 fieldbus data-link layer in terms of
a) function description;
b) primitive actions and events with primitive sequence diagram;
c) the form of externally service interface and related parameters.
The purpose of this document is to define the services provided to:
• the Type 28 fieldbus application layer at the boundary between the application and data-link
layers of the fieldbus reference model;
• systems management at the boundary between the data-link layer and systems
management of the fieldbus reference model.
Type 28 DL-service provides both a connected and a connectionless subset of those services
provided by OSI data-link protocols as specified in ISO/IEC 8886.
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-sensitive
communications. A secondary objective is to provide migration paths from previously-existing
industrial communications protocols.
This specification can 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 does it 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
fulfills the Type 28 data-link layer services defined in this document.
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 the IEC 61784-1 series and the IEC 61784-2 series 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 61158-2:2023, Industrial communication networks – Fieldbus specifications – Part 2:
Physical layer specification and service definition
IEC 61158-4-28:2023, Industrial communication networks – Fieldbus specifications – Part 4-28:
Data-link layer protocol specification – Type 28 elements
ISO/IEC 7498-1, Information technology – Open Systems Interconnection – Basic Reference
Model – Basic Reference Model: The Basic Model
ISO/IEC 7498-3, Information technology – Open Systems Interconnection – Basic Reference
Model: Naming and addressing
ISO/IEC 10731:1994, Information technology – Open Systems Interconnection – Basic
Reference Model – Conventions for the definition of OSI services
ISO/IEC 8886, Information technology – Open Systems Interconnection – Data link service
definition
ISO/IEC/IEEE 8802-3:2021, Information technology – Telecommunications and information
exchange between systems – Local and metropolitan area networks – Specific requirements –
Part 3: Standard for Ethernet
3 Terms, definitions, abbreviated terms and conventions
For the purposes of this document, the following terms, definitions, symbols, abbreviated terms
and conventions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://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:

– 10 – IEC 61158-3-28:2023 © IEC 2023
3.1.1 DL-address [ISO/IEC 7498-3]
3.1.2 DL-address-mapping [ISO/IEC 7498-1]
3.1.3 called-DL-address [ISO/IEC 7498-3]
3.1.4 calling-DL-address [ISO/IEC 7498-3]
3.1.5 centralized multi-end-point-connection [ISO/IEC 7498-1]
3.1.6 DL-connection [ISO/IEC 7498-1]
3.1.7 DL-connection-end-point [ISO/IEC 7498-1]
3.1.8 DL-connection-end-point-identifier [ISO/IEC 7498-1]
3.1.9 DL-connection-mode transmission [ISO/IEC 7498-1]
3.1.10 DL-connectionless-mode transmission [ISO/IEC 7498-1]
3.1.11 correspondent (N)-entities [ISO/IEC 7498-1]
correspondent DL-entities (N=2)
correspondent Ph-entities (N=1)
3.1.12 DL-duplex-transmission [ISO/IEC 7498-1]
3.1.13 (N)-entity [ISO/IEC 7498-1]
DL-entity (N=2)
Ph-entity (N=1)
3.1.14 DL-facility [ISO/IEC 7498-1]
3.1.15 flow control [ISO/IEC 7498-1]
3.1.16 (N)-layer [ISO/IEC 7498-1]
DL-layer (N=2)
DL-layer (N=1)
3.1.17 layer-management [ISO/IEC 7498-1]
3.1.18 DL-local-view [ISO/IEC 7498-3]
3.1.19 DL-name [ISO/IEC 7498-3]
3.1.20 naming-(addressing)-domain [ISO/IEC 7498-3]
3.1.21 peer-entities [ISO/IEC 7498-1]
3.1.22 primitive name [ISO/IEC 7498-3]
3.1.23 DL-protocol [ISO/IEC 7498-1]
3.1.24 DL-protocol-connection-identifier [ISO/IEC 7498-1]
3.1.25 DL-protocol-data-unit [ISO/IEC 7498-1]
3.1.26 DL-relay [ISO/IEC 7498-1]
3.1.27 reset [ISO/IEC 7498-1]
3.1.28 responding-DL-address [ISO/IEC 7498-3]
3.1.29 routing [ISO/IEC 7498-1]
3.1.30 segmenting [ISO/IEC 7498-1]
3.1.31 (N)-service [ISO/IEC 7498-1]
DL-service (N=2)
Ph-service (N=1)
3.1.32 (N)-service-access-point [ISO/IEC 7498-1]
DL-service-access-point (N=2)
Ph-service-access-point (N=1)
3.1.33 DL-service-access-point-address [ISO/IEC 7498-3]
3.1.34 DL-service-connection-identifier [ISO/IEC 7498-1]
3.1.35 DL-service-data-unit [ISO/IEC 7498-1]
3.1.36 DL-simplex-transmission [ISO/IEC 7498-1]

3.1.37 DL-subsystem [ISO/IEC 7498-1]
3.1.38 systems-management [ISO/IEC 7498-1]
3.1.39 DLS-user-data [ISO/IEC 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 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
3.3 Common data-link service terms and definitions
For 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.
3.3.1
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
– 12 – IEC 61158-3-28:2023 © IEC 2023
3.3.2
DLSAP
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.)

Note 2 to entry: DLSAPs and PhSAPs are depicted as ovals spanning the boundary between two adjacent layers.
Note 3 to entry: DL-addresses are depicted as designating small gaps (points of access) in the DLL portion of a
DLSAP.
Note 4 to entry: 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
3.3.3
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 where each DLSAP is from 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.
3.3.5
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.
3.3.6
frame
denigrated synonym for DLPDU
3.3.7
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 may also have a single group DL-address associated with more than one DLSAP.
3.3.8
node
single DL-entity as it appears on one local link
3.3.9
receiving 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.
3.3.10
sending DLS-user
DL-service user that acts as a source of DLS-user-data
3.4 Additional Type 28 data-link specific definitions
3.4.1
control device
device that controls all field devices for logical operations, timing, calculations, etc.
3.4.2
management node
device for allocating and managing Type 28 network physical communication resources
3.4.3
terminal node
device in Type 28 network that communicates based on allocated physical communication
resources
3.4.4
clock synchronization
clock calibration of the terminal node device
3.4.5
cyclic time
time of cyclic processing of a device or module
3.4.6
RT data
data sensitive to time deterministic requirements
3.4.7
non-RT data
data insensitive to time deterministic requirements

– 14 – IEC 61158-3-28:2023 © IEC 2023
3.4.8
orthogonal frequency division multiplexing (OFDM) symbol
minimum data transmission unit in time domain that includes all subcarriers in frequency based
on OFDM technology
3.4.9
upper sideband
subcarriers with a frequency range from 16,896 MHz to 32,256 MHz on an OFDM symbol
3.4.10
lower sideband
subcarriers with a frequency range from 1,536 MHz to 16,896 MHz on an OFDM symbol
3.4.11
carrier mode
data transfer mode over available resources made up of OFDM symbols
3.4.12
working mode
OFDM operation in a specific transmission mode, RS coding, convolutional coding, and
modulation mode
3.4.13
cyclic frame
signal frames which are processed in a regular and repetitive manner
3.4.14
cyclic symbol
OFDM symbols in signal frames which are processed in a regular and repetitive manner
3.4.15
code block
octet sequence of data interaction between the Type 28 physical layer entity and the
Type 28 data-link layer entity
3.4.16
data transmission channel
logical channel of the Type 28 data-link layer mapped by the determined physical
communication resource for transmitting data-link layer data frames
3.4.17
BITMAP
bitmap format type including Width and Mask_Info information and the length range from
2 octets to 256 octets
Note 1 to entry: See Figure 2.
Note 2 to entry: Width has 1 octet and its value indicates the number of the octets of Mask_Info.
Note 3 to entry: Mask_Info represented by bit. The octet length is Width value and the bit length is Width × 8.

Figure 2 – Bitmap Data type diagram
3.5 Common symbols and abbreviations
NOTE Many symbols and abbreviations are common to more than one protocol Type; they are not necessarily used
by all protocol Types.
DL- Data-link layer (as a prefix)
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)
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
3.6 Additional Type 28 symbols and abbreviations
For the purposes of this document, the following abbreviations apply.
AL Application layer
C/S Client/Server
CLMDTA Connection-less Mode Data Transmission with Acknowledge
CLMDTNA Connection-less Mode Data Transmission with No Acknowledge
CLMDTRA Connection-less Mode Data Transmission with Request and Acknowledge
CLMDTRRNA Connection-less Mode Data Transmission with Request and Response but No
Acknowledge
CMDTA Connection Mode Data Transmission with Acknowledge
CMDTNA Connection Mode Data Transmission with No Acknowledge

– 16 – IEC 61158-3-28:2023 © IEC 2023
DLCSS Data-link clock synchronization service
DLDE Data-link data entity
DLE Data-link entity
DLMS-user Data-link management service user
DLP Data-link protocol
DLS-user Data-link service user
DTC Data transmission channel
DTS Data transmission service
DLPDU Data-link protocol data unit
MAC Medium access control
MN Management node
NodeID Node identifier
nRT non-Real-Time
OFDM Orthogonal Frequency Division Multiplexing
RT Real-Time
RTA Real-Time acyclic
RTC Real-Time cyclic
TM Transmit mode
TN Terminal node
4 Type 28 Data-link service
4.1 Overview
This document specifies the Type 28 data-link services (DLS) based on the Type 28 physical
layer. The Type 28 DLL provides two services between management nodes and terminal nodes:
a) Data transmission service (DTS) based on connection-less mode or connection mode,
b) Data-link Clock synchronization service (DLCSS) with delay measurement and clock
interruption.
These services are the typical services required for industrial automation applications.
Table 1 indicates the description of DTS status output value.
Table 1 – DTS status output value
Status name Status coding Status description
DTS_SUCCESS 0x00000100 DTS success
DTS_FAILED 0x00000101 DTS failure
DTS_ERR_CONNECT 0x00000102 DTS connection error
DTS_ERR_PARA 0x00000103 DTS parameter error
DTS_ERR_DATA 0x00000104 DTS data error
DTS_ERR_CRC 0x00000105 Transmitted data CRC error
DTS_DLDE_NO_EXIST 0x00000106 DLDE does not exist
DTS_ERR_UNKNOW 0x0000010F Unknown DTS error

Table 2 indicates the description of DLCSS status return value.

Table 2 – DLCSS status return value
Status name Status coding Status description
DLCSS_SUCCESS 0x00000400 DLCSS processing successes
DLCSS_FAILED 0x00000401 DLCSS processing failed
DLCSS_ERR_PARA 0x00000402 DLCSS parameter error
DLCSS_ERR_TIME 0x00000403 DLCSS time error
DLCSS_ERR_CRC 0x00000404 Data for DLCSS with incorrect CRC value
DLCSS_NO_CLOCK 0x00000405 No clock synchronization entity clock
DLCSS_NO_RESOURCE 0x00000406 DLCSS resource is not enough
DLCS_CLASH_SYNC 0x00000407 DLCSS synchronization clash
DLCSS_NOT_SUPPORT 0x00000408 Current DLCSS operation is not supported
DLCSS_ERR_UNKNOWN 0x0000040F Unknown error in DLCSS

4.2 Model of the DLS
4.2.1 General
The DLS of Type 28 adopts 4 connection-less mode DTSs and 2 connection mode DTSs.
a) Connection-less Mode Data Transmission with Acknowledge (CLMDTA)
b) Connection-less Mode Data Transmission with No Acknowledge (CLMDTNA)
c) Connection-less Mode Data Transmission with Request and Acknowledge (CLMDTRA)
d) Connection-less Mode Data Transmission with Request and Response but No Acknowledge
(CLMDTRRNA)
e) Connection Mode Data Transmission with Acknowledge (CMDTA)
f) Connection Mode Data Transmission with No Acknowledge (CMDTNA)
4.2.2 Connection-less mode data transmission with acknowledge (CLMDTA)
Based on the service model, the local DLS-user encapsulates the data request through the
DLSDU format and sends the request to a remote DLS-user. At
...