IEC 61158-6-15:2010

IEC 61158-6-15 ®
Edition 2.0 2010-08
INTERNATIONAL
STANDARD
Industrial communication networks – Fieldbus specifications –
Part 6-15: Application layer protocol specification – Type 15 elements

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IEC 61158-6-15 ®
Edition 2.0 2010-08
INTERNATIONAL
STANDARD
Industrial communication networks – Fieldbus specifications –
Part 6-15: Application layer protocol specification – Type 15 elements

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
XD
ICS 25.04.40; 35.100.70; 35.110 ISBN 978-2-88912-131-1
– 2 – 61158-6-15 © IEC:2010(E)
CONTENTS
FOREWORD.0H6
INTRODUCTION.1H8
1 Scope.2H9
1.1 General .3H9
1.2 Specifications.4H9
1.3 Conformance.5H10
2 Normative references .6H10
3 Terms and definitions, abbreviations, symbols and conventions .7H10
3.1 Terms and definitions .8H10
3.2 Abbreviations and symbols.9H17
3.3 Conventions .10H19
3.4 Conventions used in state machines .11H21
4 Abstract syntax for client/server .12H22
5 Transfer syntax for client/server .13H22
5.1 General .14H22
5.2 Common APDU structure .15H22
5.3 Service-specific APDU structures .16H26
5.4 Data representation ‘on the wire’ .17H51
6 Abstract syntax for publish/subscribe .18H51
7 Transfer syntax for publish/subscribe .19H52
7.1 General .20H52
7.2 APDU structure .21H52
7.3 Sub-message structure .22H53
7.4 APDU interpretation .23H55
7.5 Service specific APDU structures .24H57
7.6 Common data representation for publish/subscribe .25H79
8 Structure of FAL protocol state machines .26H83
9 AP-context state machines for client/server .27H85
10 FAL service protocol machine (FSPM) for client/server.28H85
10.1 General .29H85
10.2 FSPM state tables .30H85
10.3 Functions used by FSPM.31H92
10.4 Parameters of FSPM/ARPM primitives .32H92
10.5 Client/server server transactions .33H92
11 Application relationship protocol machines (ARPMs) for client/server .34H94
11.1 Application relationship protocol machines (ARPMs) .35H94
11.2 AREP state machine primitive definitions .36H95
11.3 AREP state machine functions .37H96
12 DLL mapping protocol machine (DMPM) for client/server.38H96
12.1 AREP mapping to data link layer .39H96
12.2 DMPM states.40H97
12.3 DMPM state machine .41H97
12.4 Primitives exchanged between data link layer and DMPM .42H98
12.5 Client/server on TCP/IP.43H98
13 AP-Context state machines for publish/subscribe .44H102

61158-6-15 © IEC:2010(E) – 3 –
14 Protocol machines for publish/subscribe.45H102
14.1 General .46H102
14.2 Publish/subscribe on UDP .47H104
Bibliography.48H105

Figure 1 – APDU Format.49H22
Figure 2 – Client to server confirmed service request.50H24
Figure 3 – Normal response from server to client.51H24
Figure 4 – Exception response from server to client.52H24
Figure 5 – Client to server unconfirmed service request.53H25
Figure 6 – Publish/subscribe APDU .54H52
Figure 7 – Flags of issue request .55H58
Figure 8 – Flags of heartbeat request .56H60
Figure 9 – Flags of VAR request .57H64
Figure 10 – Flags of GAP request .58H66
Figure 11 – Flags of ACK request .59H68
Figure 12 – Flags of INFO_DST request .60H72
Figure 13 – Flags of INFO_REPLY request.61H73
Figure 14 – Flags of INFO_SRC request.62H75
Figure 15 – Flags of INFO_TS request.63H77
Figure 16 – Flags of PAD request .64H78
Figure 17 – Encoding of octet .65H80
Figure 18 – Encoding of boolean .66H80
Figure 19 – Encoding of unsigned short .67H80
Figure 20 – Encoding of unsigned long .68H80
Figure 21 – Encoding of unsigned long long.69H81
Figure 22 – Encoding of float .70H81
Figure 23 – Encoding of double .71H81
Figure 24 – Relationships among protocol machines and adjacent layers .72H84
Figure 25 – State transition diagram of FSPM.73H85
Figure 26 – Transaction state machine, per connection .74H86
Figure 27 – Client/server server transactions .75H93
Figure 28 – State transition diagram of the Client ARPM.76H94
Figure 29 – State transition diagram of the server ARPM .77H95
Figure 30 – State transition diagram of DMPM .78H97
Figure 31 – APDU Format.79H98
Figure 32 – TCP/IP PDU Format .80H99
Figure 33 – Publish/subscribe receiver .81H103

Table 1 – Conventions used for state machines .82H21
Table 2 – Exception code.83H25
Table 3 – Read discretes request .84H26
Table 4 – Read discretes response.85H26

– 4 – 61158-6-15 © IEC:2010(E)
Table 5 – Read coils request .86H27
Table 6 – Read coils response.87H27
Table 7 – Write single coil request .88H28
Table 8 – Write single coil response .89H28
Table 9 – Write multiple coils request .90H29
Table 10 – Write multiple coils response.91H29
Table 11 – Broadcast write single coil request .92H30
Table 12 – Broadcast write multiple coils request.93H31
Table 13 – Read input registers request .94H31
Table 14 – Read input registers response.95H32
Table 15 – Read holding registers request.96H32
Table 16 – Read holding registers response .97H33
Table 17 – Write single holding register request .98H33
Table 18 – Write single holding register response.99H34
Table 19 – Write multiple holding registers request.100H34
Table 20 – Write multiple holding registers response .101H35
Table 21 – Mask write holding register request .102H36
Table 22 – Mask write holding register request .103H36
Table 23 – Read/Write multiple holding registers request.104H37
Table 24 – Read/Write multiple holding registers response .105H38
Table 25 – Read FIFO request.106H38
Table 26 – Read FIFO response .107H39
Table 27 – Broadcast write single holding register request.108H40
Table 28 – Broadcast write multiple holding registers request .109H41
Table 29 – Read file record request .110H42
Table 30 – Read file record response .111H43
Table 31 – Write file record request .112H44
Table 32 – Write file record response .113H46
Table 33 – Read device identification request.114H47
Table 34 – Device identification categories .115H48
Table 35 – Read device ID code .116H48
Table 36 – Read device identification response .117H49
Table 37 – Conformity level .118H50
Table 38 – Requested vs. returned known objects .119H51
Table 39 – APDU structure .120H53
Table 40 – Sub-message structure .121H54
Table 41 – Publish/subscribe service identifier encoding .122H54
Table 42 – Attributes changed modally and affecting APDUs interpretations .123H56
Table 43 – Issue request .124H57
Table 44 – Meaning of issue request flags .125H58
Table 45 – Interpretation of issue.126H59
Table 46 – Heartbeat request .127H60
Table 47 – Meaning of heartbeat request flags .128H61

61158-6-15 © IEC:2010(E) – 5 –
Table 48 – Interpretation of heartbeat .129H62
Table 49 – VAR request.130H63
Table 50 – Meaning of VAR request flags .131H64
Table 51 – Interpretation of VAR.132H65
Table 52 – GAP request.133H66
Table 53 – Meaning of GAP request flags .134H67
Table 54 – Interpretation of GAP.135H67
Table 55 – ACK request.136H68
Table 56 – Meaning of ACK request flags .137H69
Table 57 – Interpretation of ACK.138H69
Table 58 – Header request .139H70
Table 59 – Change in state of the receiver.140H71
Table 60 – INFO_DST request.141H71
Table 61 – Meaning of INFO_DST request flags .142H72
Table 62 – INFO_REPLY request .143H73
Table 63 – Meaning of INFO_REPLY request flags .144H74
Table 64 – INFO_SRC request .145H75
Table 65 – Meaning of INFO_SRC request flags .146H75
Table 66 – INFO_TS request .147H76
Table 67 – Meaning of INFO_TS request flags.148H77
Table 68 – PAD request.149H78
Table 69 – Meaning of PAD request flags .150H78
Table 70 – Semantics .151H79
Table 71 – FSPM state table – client transactions.152H87
Table 72 – FSPM state table – server transactions .153H92
Table 73 – Function MatchInvokeID().154H92
Table 74 – Function HighBit() .155H92
Table 75 – Parameters used with primitives exchanged between FSPM and ARPM .156H92
Table 76 – Client ARPM states .157H94
Table 77 – Client ARPM state table .158H94
Table 78 – Server ARPM states .159H94
Table 79 – Server ARPM state table .160H95
Table 80 – Primitives issued from ARPM to DMPM .161H95
Table 81 – Primitives issued by DMPM to ARPM .162H95
Table 82 – Parameters used with primitives exchanged between ARPM and DMPM .163H96
Table 83 – DMPM state descriptions.164H97
Table 84 – DMPM state table – client transactions.165H97
Table 85 – DMPM state table – server transactions .166H98
Table 86 – Primitives exchanged between data-link layer and DMPM .167H98
Table 87 – Encapsulation parameters for client/server on TCP/IP .168H99

– 6 – 61158-6-15 © IEC:2010(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INDUSTRIAL COMMUNICATION NETWORKS –
FIELDBUS SPECIFICATIONS –
Part 6-15: Application layer protocol specification –
Type 15 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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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
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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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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.
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.
NOTE 1 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 profile parts. Use of the various protocol types in other
combinations may require permission from their respective intellectual-property-right holders.
International Standard IEC 61158-6-15 has been prepared by subcommittee 65C: Industrial
networks, of IEC technical committee 65: Industrial-process measurement, control and
automation.
This second edition cancels and replaces the first edition published in 2007. This edition
constitutes a technical revision.
The main changes with respect to the previous edition are listed below:
• editorial corrections.
61158-6-15 © IEC:2010(E) – 7 –
The text of this standard is based on the following documents:
FDIS Report on voting
65C/607/FDIS 65C/621/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.
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.
NOTE 2 The revision of this standard will be synchronized with the other parts of the IEC 61158 series.

– 8 – 61158-6-15 © IEC:2010(E)
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 application protocol provides the application service by making use of the services
available from the data-link or other immediately lower 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 application entities (AEs) 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:
• as a guide for implementers and designers;
• for use in the testing and procurement of equipment;
• as part of an agreement for the admittance of systems into the open systems environment;
• 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.

61158-6-15 © IEC:2010(E) – 9 –
INDUSTRIAL COMMUNICATION NETWORKS –
FIELDBUS SPECIFICATIONS –
Part 6-15: Application layer protocol specification –
Type 15 elements
1 Scope
1.1 General
The Fieldbus Application Layer (FAL) provides user programs with a means to access the
fieldbus communication environment. In this respect, the FAL can be viewed as a “window
between corresponding application programs.”
This standard provides common elements for basic time-critical and non-time-critical
messaging communications between application programs in an automation environment and
material specific to Type 15 fieldbus. 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 standard defines in an abstract way the externally visible behavior provided by the Type
15 fieldbus Application Layer in terms of
a) the abstract syntax defining the application layer protocol data units conveyed between
communicating application entities,
b) the transfer syntax defining the application layer protocol data units conveyed between
communicating application entities,
c) the application context state machine defining the application service behavior visible
between communicating application entities; and
d) the application relationship state machines defining the communication behavior visible
between communicating application entities; and.
The purpose of this standard is to define the protocol provided to
a) define the wire-representation of the service primitives defined in IEC 61158-5-15, and
b) define the externally visible behavior associated with their transfer.
This standard specifies the protocol of the Type 15 IEC fieldbus Application Layer, in
conformance with the OSI Basic Reference Model (ISO/IEC 7498) and the OSI Application
Layer Structure (ISO/IEC 9545).
1.2 Specifications
The principal objective of this standard is to specify the syntax and behavior of the application
layer protocol that conveys the application layer services defined in IEC 61158-5-15.
A secondary objective is to provide migration paths from previously-existing industrial
communications protocols. It is this latter objective which gives rise to the diversity of
protocols standardized in IEC 61158-6.

– 10 – 61158-6-15 © IEC:2010(E)
1.3 Conformance
This standard does not specify individual implementations or products, nor does it constrain
the implementations of application layer entities within industrial automation systems.
Conformance is achieved through implementation of this application layer protocol
specification.
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
IEC 61158-5-15:20100F , Industrial communication networks – Fieldbus specifications - Part
5-15: Application layer service definition – Type 15 elements
ISO/IEC 7498-1, Information technology – Open Systems Interconnection – Basic Reference
Model: The Basic Model
ISO/IEC 8822, Information technology – Open Systems Interconnection – Presentation
service definition
ISO/IEC 8824-1, Information technology – Abstract Syntax Notation One (ASN.1):
Specification of basic notation
ISO/IEC 9545, Information technology – Open Systems Interconnection – Application Layer
structure
3 Terms and definitions, abbreviations, symbols and conventions
3.1 Terms and definitions
For the purposes of this document, the following terms as defined in these publications apply:
3.1.1 ISO/IEC 7498-1 terms
a) application entity
b) application process
c) application protocol data unit
d) application service element
e) application entity invocation
f) application process invocation
g) application transaction
h) real open system
i) transfer syntax
3.1.2 ISO/IEC 8822 terms
a) abstract syntax
b) presentation context
___________
To be published.
61158-6-15 © IEC:2010(E) – 11 –
3.1.3 ISO/IEC 9545 terms
a) application-association
b) application-context
c) application context name
d) application-entity-invocation
e) application-entity-type
f) application-process-invocation
g) application-process-type
h) application-service-element
i) application control service element
3.1.4 ISO/IEC 8824-1 terms
a) object identifier
b) type
3.1.5 IEC/TR 61158-1 terms
The following IEC/TR 61158-1 terms apply.
3.1.5.1
application
function or data structure for which data is consumed or produced
3.1.5.2
application layer interoperability
capability of application entities to perform coordinated and cooperative operations using the
services of the FAL
3.1.5.3
application object
object class that manages and provides the run time exchange of messages across the
network and within the network device
NOTE Multiple types of application object classes may be defined.
3.1.5.4
application process
part of a distributed application on a network, which is located on one device and
unambiguously addressed
3.1.5.5
application process identifier
distinguishes multiple application processes used in a device
3.1.5.6
application process object
component of an application process that is identifiable and accessible through an FAL
application relationship
NOTE Application process object definitions are composed of a set of values for the attributes of their class.
3.1.5.7
application process object class
class of application process objects defined in terms of the set of their network-accessible
attributes and services
– 12 – 61158-6-15 © IEC:2010(E)
3.1.5.8
application relationship
cooperative association between two or more application-entity-invocations for the purpose of
exchange of information and coordination of their joint operation
NOTE This relationship is activated either by the exchange of application-protocol-data-units or as a result of
preconfiguration activities.
3.1.5.9
application relationship endpoint
context and behavior of an application relationship as seen and maintained by one of the
application processes involved in the application relationship
NOTE Each application process involved in the application relationship maintains its own application relationship
endpoint.
3.1.5.10
application service element
application-service-element that provides the exclusive means for establishing and
terminating all application relationships
3.1.5.11
attribute
description of an externally visible characteristic or feature of an object
NOTE 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.
3.1.5.12
behavior
indication of how the object responds to particular events
NOTE Its description includes the relationship between attribute values and services.
3.1.5.13
class
set of objects, all of which represent the same kind of system component
NOTE 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.
3.1.5.14
class attributes
attribute that is shared by all objects within the same class
3.1.5.15
class code
unique identifier assigned to each object class
3.1.5.16
class specific service
service defined by a particular object class to perform a required function which is not
performed by a common service
NOTE A class specific object is unique to the object class which defines it.
3.1.5.17
Client
(a) object which uses the services of another (server) object to perform a task

61158-6-15 © IEC:2010(E) – 13 –
(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
3.1.5.18
conveyance path
unidirectional flow of APDUs across an application relationship
3.1.5.19
cyclic
term used to describe events which repeat in a regular and repetitive manner
3.1.5.20
dedicated AR
AR used directly by the FAL user
NOTE On Dedicated ARs, only the FAL Header and the user data are transferred.
3.1.5.21
device
physical hardware connection to the link
NOTE A device may contain more than one node.
3.1.5.22
device profile
collection of device dependent information and functionality providing consistency between
similar devices of the same device type
3.1.5.23
dynamic AR
AR that requires the use of the AR establishment procedures to place it into an established
state
3.1.5.24
endpoint
one of the communicating entities involved in a connection
3.1.5.25
error
discrepancy between a computed, observed or measured value or condition and the specified
or theoretically correct value or condition
3.1.5.26
error class
general grouping for error definitions
NOTE Error codes for specific errors are defined within an error class.
3.1.5.27
error code
identification of a specific type of error within an error class
3.1.5.28
FAL subnet
networks composed of one or more data link segments
NOTE Subnets are permitted to contain bridges, but not routers. FAL subnets are identified by a subset of the
network address.
– 14 – 61158-6-15 © IEC:2010(E)
3.1.5.29
logical device
FAL class that abstracts a software component or a firmware component as an autonomous
self-contained facility of an automation device
3.1.5.30
management information
network-accessible information that supports managing the operation of the fieldbus system,
including the application layer
NOTE Managing includes functions such as controlling, monitoring, and diagnosing.
3.1.5.31
network
series of nodes connected by some type of communication medium
NOTE The connection paths between any pair of nodes can include repeaters, routers and gateways.
3.1.5.32
peer
role of an AR endpoint in which it is capable of acting as both client and server
3.1.5.33
pre-defined AR endpoint
AR endpoint that is defined locally within a device without use of the create service
NOTE Pre-defined ARs that are not pre-established are established before being used.
3.1.5.34
pre-established AR endpoint
AR endpoint that is placed in an established state during configuration of the AEs that control
its endpoints
3.1.5.35
Publisher
role of an AR endpoint in which it transmits APDUs onto the fieldbus for consumption by one
or more subscribers
NOTE The publisher may not be aware of the identity or the number of subscribers and it may publish its APDUs
using a dedicated AR. Two types of publishers are defined by this standard, Pull Publishers and Push Publishers,
each of which is defined separately.
3.1.5.36
server
a) role of an AREP in which it returns a confirmed service response APDU to the client that
initiated the request
b) object which provides services to another (client) object
3.1.5.37
service
operation or function than an object and/or object class performs upon request from another
object and/or object class
NOTE A set of common services is defined and provisions for the definition of object-specific services are
provided. Object-specific services are those which are defined by a particular object class to perform a required
function which is not performed by a common service.
3.1.5.38
subscriber
role of an AREP in which it receives APDUs produced by a publisher

61158-6-15 © IEC:2010(E) – 15 –
NOTE Two types of subscribers are defined by this standard, pull subscribers and push subscribers, each of
which is defined separately.
3.1.6 Specific definitions for client/server
3.1.6.1
coils, discrete outputs
application process object, a set of coils, characterized by the address of a coil and a quantity
of coils, this set is also called discrete outputs when associated with field outputs
3.1.6.2
discrete, discrete input
application process object, addressed by an unsigned number and having a width of one bit,
representing a 1-bit encoded status value, read-only, with the value '1' encoding the status
ON and the value '0' encoding the status OFF, also called discrete input, especially when
associated with field inputs
3.1.6.3
discrete inputs, discretes
application process object, a set of discretes, characterized by the address of a discrete and
a quantity of discretes, this set is also called discrete inputs, especially when associated with
field inputs
3.1.6.4
coil, discrete output
application process object, addressed by an unsigned number and having a width of one bit,
representing a 1-bit encoded status value, read-write, with the value '1' encoding the status
ON and the value '0' encoding the status OFF, also called discrete out
...