IEC 61158-4-11:2007

IEC 61158-4-11
Edition 1.0 2007-12
INTERNATIONAL
STANDARD
Industrial communication networks – Fieldbus specifications –
Part 4-11: Data-link layer protocol specification – Type 11 elements

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IEC 61158-4-11
Edition 1.0 2007-12
INTERNATIONAL
STANDARD
Industrial communication networks – Fieldbus specifications –
Part 4-11: Data-link layer protocol specification – Type 11 elements

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
XC
ICS 35.100.20; 25.040.40 ISBN 2-8318-9436-0

– 2 – 61158-4-11 © IEC:2007(E)

CONTENTS
FOREWORD.5

INTRODUCTION.7

1 Scope.8

1.1 General .8

1.2 Specifications.8

1.3 Procedures.8

1.4 Applicability.9

1.5 Conformance.9
2 Normative references .9
3 Terms, definitions, symbols and abbreviations.9
3.1 Reference model terms and definitions.9
3.2 Service convention terms and definitions.11
3.3 Terms and definitions .12
3.4 Symbols and abbreviations.16
4 Overview of the DL-protocol .17
4.1 General .17
4.2 Overview of the medium access control.17
4.3 Service assumed from the PhL .18
4.4 DLL architecture.19
4.5 Access control machine and schedule support functions .21
4.6 Local parameters, variable, counters, timers .22
5 General structure and encoding of PhIDUs and DLPDU and related elements of
procedure.32
5.1 Overview .32
5.2 PhIDU structure and encoding.32
5.3 Common MAC frame structure, encoding and elements of procedure .33
5.4 Elements of the MAC frame.34
5.5 Order of bit transmission .38
5.6 Invalid DLPDU.38
6 DLPDU-specific structure, encoding and elements of procedure .39
6.1 General .39
6.2 Synchronization DLPDU (SYN).39
6.3 Transmission complete DLPDU (CMP) .44
6.4 In-ring request DLPDU (REQ) .45
6.5 Claim DLPDU (CLM) .46
6.6 Command (COM) DLPDU.47
6.7 Cyclic data and cyclic data with transmission complete DLPDU (DT) and
(DT-CMP).48
6.8 RAS DLPDU (RAS) .49
7 DLE elements of procedure .50
7.1 Overall structure.50
7.2 Initialization.51
7.3 Cyclic transmission TX/RX control (CTRC) .52
7.4 Sporadic TX/RX control (STRC) .56
7.5 Access control machine (ACM).59
7.6 Redundancy medium control (RMC) .67
7.7 Serializer and deserializer .74

61158-4-11 © IEC:2007(E) – 3 –

7.8 DLL management protocol.74

Bibliography.80

Figure 1 – Relationships of DLSAPs, DLSAP-addresses and group DL-addresses .13

Figure 2 – Basic principle of medium access control .18

Figure 3 – Interaction of PhS primitives to DLE.19

Figure 4 – Data-link layer internal architecture .21

Figure 5 – Common MAC frame format for DLPDUs.33

Figure 6 – Sporadic DLPDU format.34

Figure 7 – Structure of FC field.35
Figure 8 – Structure of SYN DLPDU.39
Figure 9 – Structure of CMP DLPDU .44
Figure 10 – Structure of the REQ DLPDU.45
Figure 11 – Structure of CLM DLPDU .46
Figure 12 – Structure of COM DLPDU.47
Figure 13 – Structure of DT DLPDU.48
Figure 14 – Structure of RAS DLPDU.49
Table 18 – RAS parameter : 3rd and 4th octets.49
Figure 15 – Overall structure of DLL .51
Figure 16 – DLE state transition.52
Figure 17 – State transition diagram of CTRC.54
Figure 18 – State transition diagram of STRC .57
Table 29 – Primitives exchanged between ACM and RMC .60
Figure 19 – State transition diagram of ACM.62
Figure 20 – State transition diagram of RMC sending and send arbitration .69
Figure 21 – State transition diagram of RMC receiving.72
Figure 22 – State transition diagram of DLM .77

Table 1 – Data-link layer components.20
Table 2 – Mandatory DLE-variables and permissible values.22
Table 3 – Observable variables and their value ranges .23

Table 4 – F-type: DLPDU type.35
Table 5 – FCS length, polynomials and constants .36
Table 6 – PN -parameter: 3rd octet .40
Table 7 – CW -parameters: 4th octet.40
Table 8 – PM parameter.40
Table 9 – RMSEL parameter .41
Table 10 – ST-parameter: 5th octet.41
Table 11 – Th-parameter: 6th, 7th and 8th octets.41
Table 12 – Tm-parameter: 9th and 10th octets .42
Table 13 – Ts-parameter: 11th and 12th octets.42
Table 14 – Tl-parameter: 13th and 14th octets .42
Table 15 – LL parameters: 15th to 46th octets .43

– 4 – 61158-4-11 © IEC:2007(E)

Table 16 – CLM parameter: 4th octet .46

Table 17 – DT parameter: 3rd and 4th octets .48

Table 18 – RAS parameter : 3rd and 4th octets.49

Table 19 – Primitives exchanged between DLS-user and CTRC.53

Table 20 – Primitives exchanged between CTRC and ACM.53

Table 21 – Parameters used with primitives exchanged between DLS-user and CTRC .54

Table 22 – CTRC state table.55

Table 23 – CTRC functions table .56

Table 24 – Primitives exchanged between DLS-user and STRC.56
Table 25 – Primitives exchanged between STRC and ACM.57
Table 26 – Parameters used with primitives exchanged between DLS-user and STRC .57
Table 27 – STRC state table .58
Table 28 – STRC functions table .59
Table 29 – Primitives exchanged between ACM and RMC .60
Table 30 – Parameters used with primitives exchanged between ACM and RMC .60
Table 31 – Primitives exchanged between ACM and CTRC.60
Table 32 – Parameters used with primitives exchanged between ACM and CTRC .60
Table 33 – Primitives exchanged between ACM and STRC.61
Table 34 – Parameters used with primitives exchanged between ACM and STRC.61
Table 35 – ACM state table.63
Table 36 – ACM function table .67
Table 37 – Primitives exchanged between ACM and RMC .68
Table 38 – Primitives exchanged between RMC and derializer / deserializer.68
Table 39 – Primitives exchanged between RMC and Ph-layer .68
Table 40 – Parameters between RMC and ACM .69
Table 41 – Parameters between RMC and Ph-layer .69
Table 42 – State table of RMC sending.70
Table 43 – State table of RMC send arbitration.71
Table 44 – State table for RMC receiving.72
Table 45 – RMC function table.74
Table 46 – Primitives exchanged between DLMS-user and DLM .75

Table 47 – Parameters used with primitives exchanged between DL-user and DLM.75
Table 48 – Event-related state change variables.76
Table 49 – DLM state table .77
Table 50 – DLM function table .79

61158-4-11 © IEC:2007(E) – 5 –

INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
INDUSTRIAL COMMUNICATION NETWORKS –

FIELDBUS SPECIFICATIONS –
Part 4-11: Data-link layer protocol specification – Type 11 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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Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
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with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
NOTE  Use of some of the associated protocol types is restricted by their 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 particular data-link layer protocol type to be used with physical layer and application layer protocols in Type

combinations as specified explicitly in the IEC 61784 series. Use of the various protocol types in other
combinations may require permission from their respective intellectual-property-right holders.
IEC draws attention to the fact that it is claimed that compliance with this standard may involve the use of patents
as follows, where the [xx] notation indicates the holder of the patent right:
Type 11 and possibly other Types:
US 4,930,121 [To] Network system using token-passing bus with multiple priority levels
US 5,414,813 [To] Direct transfer from a receive buffer to a host in a token-passing type network
data transmission system
US 6,711,131 [To] Data transmitting apparatus, network interface apparatus, and data
transmitting system
IEC takes no position concerning the evidence, validity and scope of these patent rights.
The holders of these patent rights have assured IEC that they are willing to negotiate licences under reasonable
and non-discriminatory terms and conditions with applicants throughout the world. In this respect, the statement of
the holders of these patent rights are registered with IEC. Information may be obtained from:

– 6 – 61158-4-11 © IEC:2007(E)

[To] Toshiba Corporation
1-1, Shibaura 1-Chome
Minato-ku Tokyo 105-8001, Japan

Attention: Intellectual Property Rights Section.

Attention is drawn to the possibility that some of the elements of this standard may be the subject of patent rights

other than those identified above. IEC shall not be held responsible for identifying any or all such patent rights.

International Standard IEC 61158-4-11 has been prepared by subcommittee 65C: Industrial

networks, of IEC technical committee 65: Industrial-process measurement, control and

automation.
This first edition and its companion parts of the IEC 61158-4 subseries cancel and replace
IEC 61158-4:2003. This edition of this part constitutes a technical addition. This part and its
Type 11 companion parts also cancel and replace IEC/PAS 62406, published in 2005.
This edition of IEC 61158-4 includes the following significant changes from the previous
edition:
a) deletion of the former Type 6 fieldbus, and the placeholder for a Type 5 fieldbus data link
layer, for lack of market relevance;
b) addition of new types of fieldbuses;
c) division of this part into multiple parts numbered -4-1, -4-2, …, -4-19.
The text of this standard is based on the following documents:
FDIS Report on voting
65C/474/FDIS 65C/485/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 ISO/IEC Directives, Part 2.
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under http://webstore.iec.ch in the
data related to the specific publication. At this date, the publication will be:
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
NOTE  The revision of this standard will be synchronized with the other parts of the IEC 61158 series.

The 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.

61158-4-11 © IEC:2007(E) – 7 –

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/TR 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.

– 8 – 61158-4-11 © IEC:2007(E)

INDUSTRIAL COMMUNICATION NETWORKS –

FIELDBUS SPECIFICATIONS –
Part 4-11: Data-link layer protocol specification – Type 11 elements

1 Scope
1.1 General
The data-link layer provides basic time-critical messaging communications between devices in
an automation environment.
This protocol provides communication opportunities to all participating data-link entities
a) in a synchronously-starting cyclic manner, according to a pre-established schedule, and
b) in a cyclic or acyclic asynchronous manner, as requested each cycle by each of those
data-link entities.
Thus this protocol can be characterized as one which provides cyclic and acyclic access
asynchronously but with a synchronous restart of each cycle.
1.2 Specifications
This 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) procedures for giving communications opportunities to all participating DL-entities,
sequentially and in a cyclic manner for deterministic and synchronized transfer at cyclic
intervals up to one millisecond;
c) procedures for giving communication opportunities available for time-critical data
transmission together with non-time-critical data transmission without prejudice to the
time-critical data transmission;
d) procedures for giving cyclic and acyclic communication opportunities for time-critical data
transmission with prioritized access;
e) procedures for giving communication opportunities based on standard ISO/ IEC 8802-3
medium access control, with provisions for nodes to be added or removed during normal
operation;
f) 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.
1.3 Procedures
The 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.

61158-4-11 © IEC:2007(E) – 9 –

1.4 Applicability
These 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.

1.5 Conformance
This standard also specifies conformance requirements for systems implementing these
procedures. This standard does not contain tests to demonstrate compliance with such
requirements.
2 Normative references
The following referenced documents are indispensable for the application of this standard. For
dated references, only the edition cited applies. For undated references, the latest edition of
the referenced document (including any amendments) applies.
IEC 61158-3-11, Industrial communication networks – Fieldbus specifications – Part 3-11:
Data-link layer service definition – Type 11 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 – Basic Reference Model: Naming and addressing
ISO/IEC 8802-3:2000, Information technology – Telecommunications and information
exchange between systems – Local and metropolitan area networks – Specific requirements –
Part 3: Carrier sense multiple access with collision detection (CSMA/CD) access method and
Physical Layer specifications
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 standard, the following terms, definitions, symbols and abbreviations
apply.
3.1 Reference model terms and definitions
This 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]
– 10 – 61158-4-11 © IEC:2007(E)

3.1.4 correspondent (N)-entities [7498-1]
correspondent DL-entities  (N=2)

correspondent Ph-entities  (N=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]
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]

61158-4-11 © IEC:2007(E) – 11 –

3.1.36 (N)-entity [7498-1]
DL-entity
Ph-entity
3.1.37 (N)-interface-data-unit [7498-1]

DL-service-data-unit  (N=2)
Ph-interface-data-unit  (N=1)

3.1.38 (N)-layer [7498-1]
DL-layer  (N=2)
Ph-layer  (N=1)
3.1.39 (N)-service [7498-1]
DL-service  (N=2)
Ph-service  (N=1)
3.1.40 (N)-service-access-point [7498-1]
DL-service-access-point  (N=2)
Ph-service-access-point  (N=1)
3.1.41 (N)-service-access-point-address [7498-1]
DL-service-access-point-address  (N=2)
Ph-service-access-point-address  (N=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]
3.2 Service convention terms and definitions
This standard also makes use of the following terms defined in ISO/IEC 10731 as they apply
to the data-link layer:
– 12 – 61158-4-11 © IEC:2007(E)

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 Terms and definitions
3.3.1
common memory
virtual common memory over Type 11 fieldbus, which is shared by participating Type 11
fieldbus nodes and is primarily used for real-time communications by the time-critical cyclic
data service
3.3.2
data DLPDU
DLPDU that carries a DLSDU from a local DLS-user to a remote DLS-user
3.3.3
DLCEP-address
DL-address which designates either

61158-4-11 © IEC:2007(E) – 13 –

a) one peer DL-connection-end-point, or

b) one multi-peer publisher DL-connection-end-point and implicitly the corresponding set of

subscriber DL-connection-end-points where each DL-connection-end-point exists within a

distinct DLSAP and is associated with a corresponding distinct DLSAP-address

3.3.4
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
3.3.5
DLSAP
distinctive point at which DL-services are provided by a single DL-entity to a single higher-
layer entity
NOTE  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.)

DLS-user-entity
DLS-user-entity
DLS-users
DLSAP DLSAP DLSAP
DLSAP-
address DLSAP-
DLSAP-
group DL-
address
addresses
address
DL-layer
DL-entity
PhSA P PhSA P
Ph-layer
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
3.3.6
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  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.

– 14 – 61158-4-11 © IEC:2007(E)

3.3.7
(individual) DLSAP-address
DL-address that designates only one DLSAP within the extended link

NOTE  A single DL-entity may have multiple DLSAP-addresses associated with a single DLSAP.

3.3.8
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  An extended link may be composed of just a single link.
3.3.9
FCS error
error that occurs when the computed frame check sequence value after reception of all the
octets in a DLPDU does not match the expected residual
3.3.10
frame
denigrated synonym for DLPDU
3.3.11
group DL-address
DL-address that potentially designates more than one DLSAP within the extended link. 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
3.3.12
high-speed cyclic data
data conveyed by means of high-speed cyclic data transmission
3.3.13
high-speed cyclic data transmission
highest priority of time-critical cyclic data service
3.3.14
implicit token
mechanism that governs the right to transmit
NOTE  No actual token message is transmitted on the medium. Each node keeps track of the node that it believes

currently holds the right to transmit. The right to transmit is passed from node to node by keeping the node that last
transmitted. A slot time is used to allow a missing node to be skipped in the rotation.
3.3.15
low-speed cyclic data
data conveyed by means of low-speed cyclic data transmission
3.3.16
low-speed cyclic data transmission
lowest priority of time-critical cyclic data service
3.3.17
medium-speed cyclic data
data conveyed by means of medium-speed cyclic data transmission

61158-4-11 © IEC:2007(E) – 15 –

3.3.18
medium-speed cyclic data transmission

second-highest priority of time-critical cyclic data service

3.3.19
multi-peer DLC
centralized multi-end-point DL-connection offering DL-duplex-transmission between a single

distinguished DLS-user known as the publisher or publishing DLS-user, and a set of peer but

undistinguished DLS-users known collectively as the subscribers or subscribing DLS-users.

The publishing DLS-user can send to the subscribing DLS-users as a group (but not
individually), and the subscribing DLS-users can send to the publishing DLS-user (but not to

each other)
3.3.20
multipoint connection
connection from one node to many nodes
NOTE  Multipoint connections allows data transfer from a single publisher to be received by many subscriber
nodes.
3.3.21
node
single DL-entity as it appears on one local link
3.3.22
node DL-address
DL-address which designates the (single) DL-entity associated with a single node on a
specific local link
3.3.23
node-id
two-octet primary identifier for the DLE on the local link, whose values are constrained
NOTE  A permissible value is from 1 to 255. A value 0 is specifically used for SYN node, which emits SYN frame.
3.3.24
receiving DLS-user
DL-service user that acts as a recipient of DL-user-data
NOTE  A DL-service user can be concurrently both a sending and receiving DLS-user.
3.3.25
sending DLS-user
DL-service user that acts as a source of DL-user-data

3.3.26
slot-time
512-bit time of the physical signaling symbol specified in the ISO/IEC 8802-3, Clause 29
3.3.27
sporadic message data service
aperiodic message transfer which sporadically occurs upon DLS-user requesting one or more
message to transfer, and regular ISO/IEC 8802-3 Ethernet message frame is transferred by
means of this message transfer
3.3.28
SYN node
node transmitting SYN frame
– 16 – 61158-4-11 © IEC:2007(E)

3.3.29
time-critical cyclic data service

cyclic data transfer with three levels of data transmission at the same time, of which each

data transmission level is according to the data priority and the data transmission period for

real-time delivery, and of which data transmission period and total data volume for each level

can be specified in designing phase and on application needs

3.3.30
token
right to transmit on the local link

3.4 Symbols and abbreviations
3.4.1 ACM Access control machine
3.4.2 CLM Claim frame
3.4.3 CMP Transmission complete frame
3.4.4 CTRC Cyclic-transmission TX/RX control
3.4.5 COM Command frame
3.4.6 DT Cyclic data frame
3.4.7 CW Control word (as parameter of SYN DLPDU)
3.4.8 DT-CMP DT with transmission complete frame
3.4.9 FC Frame control field
3.4.10 LL Live list (as parameter of SYN DLPDU)
3.4.11 PM Periodic mode (as parameter of SYN DLPDU)
3.4.12 PN Transmission permits node number (as parameter of SYN DLPDU)
3.4.13 Pri Priority field
3.4.14 RAS RAS frame
3.4.15 REC In-ring request frame
3.4.16 RMC Redundancy medium control
3.4.17 RMSEL Redundant medium selection

3.4.18 SN Source node number field
3.4.19 ST Slot time (as parameter of SYN DLPDU)
3.4.20 SYN Synchronization frame
3.4.21 Th High-speed transmission period (as transmission period)
3.4.22 Tm Medium-speed transmission period (as transmission period)
3.4.23 Ts Sporadic-speed transmission period (as transmission period)
3.4.24 Tl Low-speed transmission period (as transmission period)

61158-4-11 © IEC:2007(E) – 17 –

4 Overview of the DL-protocol
4.1 General
This standard meets the industrial automation market objective of providing predictable time

deterministic and reliable time-critical data transfer and means, which allow co-existence with

non-time-critical data transfer over the ISO/IEC 8802-3 series communications medium, for

support of cooperation and synchronization between automation processes on field devices in

a real-time application system. 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.

4.1.1 Field of applications
In industrial control systems, several kinds of field devices such as Drives, Sensors and
Actuators, Programmable controllers, Distributed Control Systems and Human Machine
Interface devices are required to be connected with control networks. The process control
data and the state data is transferred among these field devices in the system and the
communications between these field devices requires simplicity in application programming
and to be executed with adequate response time. In most industrial automation systems such
as food, water, sewage, paper and steel, including a rolling mill, the control network is
required to provide time-critical response capability for their application, as required in
ISO/TR 13283 for time-critical communications architectures.
Plant production may be compromised due to errors, which could be introduced to the control
system if the network does not provide a time-critical response. Therefore the following
characteristics are required for a time-critical control network:
• deterministic response time between the control device nodes;
• ability to share process data seamlessly across the control system.
This protocol is applicable to such an industrial automation environment, in which time-critical
communications is primarily required. 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 specifi
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