IEC 61158-5-2:2007

Industrial communication networks - Fieldbus specifications - Part 5-2: Application layer service definition - Type 2 elements

It 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 2 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. It includes the following significant changes with respect to the previous edition deletion of the former Type 6 fieldbus, and the placeholder for a Type 5 fieldbus data-link layer, for lack of market relevance; addition of new types of fieldbuses; division of this part into multiple parts numbered.

General Information

• Status: Published
• Publication Date: 13-Dec-2007
• ICS: 25.040.40 - Industrial process measurement and control
• ICS: 35.100.70 - Application layer
• Technical Committee: SC 65C - Industrial networks
• Drafting Committee: WG 9 - TC 65/SC 65C/WG 9
• Current Stage: DELPUB - Deleted Publication
• Start Date: 05-Aug-2010
• Completion Date: 26-Oct-2025

Relations

• Replaces: IEC PAS 62413:2005 - Real-time Ethernet - EtherNet/IP(TM) with time synchronization
• Effective Date: 05-Sep-2023
• Replaces: IEC 61158-5:2003/COR1:2004 - Corrigendum 1 - Digital data communications for measurement and control - Fieldbus for use in industrial control systems - Part 5: Application layer service definition
• Effective Date: 05-Sep-2023
• Replaces: IEC 61158-5:2003 - Digital data communications for measurement and control - Fieldbus for use in industrial control systems - Part 5: Application layer service definition
• Effective Date: 05-Sep-2023
• Revised: IEC 61158-5-2:2010 - Industrial communication networks - Fieldbus specifications - Part 5-2: Application layer service definition - Type 2 elements
• Effective Date: 05-Sep-2023

Overview

IEC 61158-5-2:2007 - "Industrial communication networks - Fieldbus specifications - Part 5-2: Application layer service definition - Type 2 elements" - defines the Fieldbus Application Layer (FAL) services and objects that give user application programs a standardized window into the fieldbus environment. Edition 1.0 (2007) covers common elements for both time‑critical and non‑time‑critical messaging between automation application programs and includes Type 2 fieldbus‑specific material. The standard also documents editorial/structural changes from prior editions (removal of Type 6, placeholder for Type 5, and division into multiple parts).

Key topics and technical requirements

The standard specifies the FAL architecture, services and objects required to support application‑to‑application communication on Type 2 fieldbuses. Major technical topics include:

• FAL concepts and addressing (MAC, class, instance, attribute IDs)
• Data type ASE (Abstract Syntax Elements) and formal data type object definitions
• Communication model: ASEs, ARs (application relationships), FAL classes and permitted services
• Service primitives for configuration and runtime management: Get/Set Attribute (single/list/all), Create/Delete, Start/Stop, Reset, Save/Restore, Find_Next_Object_Instance
• Connection and transport services: CM_Open/Close, CM_Unconnected_Send, connection binding, transport classes and trigger mechanisms
• I/O and messaging services: explicit messaging, connection-oriented and connectionless transfers, acknowledged data paths
• Timing and synchronization: time windows for time‑critical actions, time synchronization groups and offset clock models
• Quality of Service (QoS), status codes and state machines for key objects (Identity, Assemblies, Acknowledge Handler, I/O producers)
• References to ISO/IEC OSI terminology and other normative references used in the specification

The document also contains detailed tables, state diagrams, and service parameter definitions that drive interoperability testing and implementation.

Applications and who uses it

IEC 61158-5-2 is intended for anyone implementing or integrating fieldbus application-layer functionality on Type 2 networks, including:

• Device and firmware vendors developing fieldbus-enabled I/O modules, controllers, gateways and communication stacks
• Automation system integrators configuring and deploying plant networks with time‑critical messaging needs
• Control engineers and safety engineers who design systems with strict time windows and determinism requirements
• Test labs and compliance bodies performing interoperability and conformance testing

Typical applications include distributed control systems, factory automation, process control and any automation scenario requiring reliable, deterministic application‑level messaging.

Related standards

• Other parts of the IEC 61158 fieldbus series (physical, data‑link, other application parts)
• ISO/IEC OSI standards referenced by the document (e.g., ISO/IEC 7498‑1) for terms and conventions

Keywords: IEC 61158-5-2, fieldbus, application layer, FAL, Type 2, industrial communication networks, time-critical messaging, automation, fieldbus services.

Standards Content (Sample)

IEC 61158-5-2
Edition 1.0 2007-12
INTERNATIONAL
STANDARD
Industrial communication networks – Fieldbus specifications –
Part 5-2: Application layer service definition – Type 2 elements

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IEC 61158-5-2
Edition 1.0 2007-12
INTERNATIONAL
STANDARD
Industrial communication networks – Fieldbus specifications –
Part 5-2: Application layer service definition – Type 2 elements

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
XH
ICS 25.040.40; 35.100.70 ISBN 2-8318-9444-1

– 2 – 61158-5-2 © IEC:2007(E)
CONTENTS
FOREWORD.5

INTRODUCTION.7

1 Scope.8

1.1 Overview .8

1.2 Specifications.9

1.3 Conformance.9

2 Normative references .9

3 Terms, definitions, symbols, abbreviations and conventions .10
3.1 ISO/IEC 7498-1 terms .10
3.2 ISO/IEC 8822 terms .10
3.3 ISO/IEC 9545 terms .11
3.4 ISO/IEC 8824 terms .11
3.5 Type 2 fieldbus data-link layer terms .11
3.6 Type 2 fieldbus application-layer specific definitions.11
3.7 Type 2 abbreviations and symbols.19
3.8 Conventions .20
4 Common concepts.22
5 Data type ASE.23
5.1 General .23
5.2 Formal definition of data type objects .23
5.3 FAL defined data types.23
5.4 Data type ASE service specification .33
6 Communication model specification.34
6.1 Concepts.34
6.2 ASEs.42
6.3 ARs .148
6.4 Summary of FAL classes .185
6.5 Permitted FAL services by AR type .186
Bibliography.188

Figure 1 – Overview of ASEs and object classes .36
Figure 2 – Addressing format using MAC, class, instance and attribute IDs .36

Figure 3 – Identity object state transition diagram .54
Figure 4 – Static Assembly state transition diagram .59
Figure 5 – Dynamic Assembly state transition diagram .60
Figure 6 – Typical timing relationships for acknowledged data production.69
Figure 7 – Example of a COS system with two acking devices .69
Figure 8 – Message flow in COS connection – one Connection object, one consumer.69
Figure 9 – Message flow in COS connection – multiple consumers .70
Figure 10 – CPF2 time synchronization offset clock model.77
Figure 11 – CPF2 time synchronization system with offset clock model .78
Figure 12 – CPF2 time synchronization group startup sequence .81
Figure 13 – Example of Find_Next_Object_Instance service . 106

61158-5-2 © IEC:2007(E) – 3 –
Figure 14 – Transmission trigger timer.142

Figure 15 – Inactivity watchdog timer.143

Figure 16 – Using tools for configuration.144

Figure 17 – Production inhibit timer .145

Figure 18 – Context of transport services within the connection model. 151

Figure 19 – Application–to–application view of data transfer . 151

Figure 20 – Data flow diagram for a link producer .152

Figure 21 – Data flow diagram for a link consumer.153

Figure 22 – Triggers .154
Figure 23 – Binding transport instances to the producer and consumer of a transport
connection that does not have a reverse data path .155
Figure 24 – Binding transport instances to the producers and consumers of a transport
connection that does have a reverse data path . 155
Figure 25 – Binding transport instances to the producer and consumers of a multipoint
connection when the transport connection does not have a reverse data path . 156
Figure 26 – Binding transport instances to the producers and consumers of a
multipoint connection when the transport connection does have reverse data paths .156

Table 1 – Valid IANA MIB printer codes for character set selection .32
Table 2 – Common elements .39
Table 3 – ST language elements.40
Table 4 – Type conversion operations.40
Table 5 – Values of implementation-dependent parameters .41
Table 6 – Extensions to IEC 61131-3 .42
Table 7 – Identity object state event matrix .55
Table 8 – Static Assembly state event matrix .59
Table 9 – Dynamic Assembly state event matrix .60
Table 10 – Message Router object Forward_Open parameters .63
Table 11 – Acknowledge Handler object state event matrix.66
Table 12 – Producing I/O application object state event matrix .67
Table 13 – Qos values .81
Table 14 – Status codes .84

Table 15 – Get_Attribute_All service parameters .86
Table 16 – Set_Attribute_All service parameters.87
Table 17 – Get_Attribute_List service parameters.89
Table 18 – Set_Attribute_List service parameters .91
Table 19 – Reset service parameters.93
Table 20 – Start service parameters .95
Table 21 – Stop service parameters.97
Table 22 – Create service parameters .98
Table 23 – Delete service parameters.100
Table 24 – Get_Attribute_Single service parameters. 101
Table 25 – Set_Attribute_Single service parameters . 103
Table 26 – Find_Next_Object_Instance service parameters . 104

– 4 – 61158-5-2 © IEC:2007(E)
Table 27 – NOP service parameters .107

Table 28 – Apply_Attributes service parameters . 108

Table 29 – Save service parameters .110

Table 30 – Restore service parameters.111

Table 31 – Group_Sync service parameters.113

Table 32 – Add_AckData_Path service parameters.115

Table 33 – Remove_AckData_Path service parameters . 116

Table 34 – Initialize service parameters .117

Table 35 – Management_Message service parameters . 119
Table 36 – CM_Open service parameters .127
Table 37 – CM_Close service parameters.129
Table 38 – CM_ Unconnected_Send service parameters . 130
Table 39 – CM_Get_Connection_Data service parameters . 132
Table 40 – CM_Search_Connection_Data service parameters . 133
Table 41 – CM_Get_Connection_Data service parameters . 134
Table 42 – I/O Connection object attribute access .139
Table 43 –Bridged Connection object attribute access .140
Table 44 – Explicit messaging object attribute access. 141
Table 45 – Connection_Bind service parameters . 146
Table 46 – Service_Name service parameters .147
Table 47 – How production trigger, transport class, and CM_RPI determine when data
is produced.150
Table 48 – Transport classes .161
Table 49 – UCMM_Create service parameters .178
Table 50 – UCMM_Delete service parameters .179
Table 51 – UCMM_Write service parameters .180
Table 52 – UCMM_Abort service parameters .181
Table 53 – TR_Write service parameters .182
Table 54 – TR_Trigger service parameters .183
Table 55 – TR_Packet_arrived service parameters .183
Table 56 – TR_Ack_received service parameters. 184

Table 57 – TR_Verify service parameters .184
Table 58 – TR_Status_updated service parameters .185
Table 59 – FAL class summary .186
Table 60 – FAL services by AR type .187

61158-5-2 © IEC:2007(E) – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
INDUSTRIAL COMMUNICATION NETWORKS –

FIELDBUS SPECIFICATIONS –
Part 5-2: Application layer service definition – Type 2 elements

FOREWORD
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
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.
International Standard IEC 61158-5-2 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 61158-5 subseries cancel and replace
IEC 61158-5:2003. This edition of this part constitutes a technical revision. This part and its
Type 2 companion parts also cancel and replace IEC/PAS 62413.
This edition of IEC 61158-5 includes the following significant changes from the previous
edition:
– 6 – 61158-5-2 © IEC:2007(E)
a) deletion of the former Type 6 fieldbus for lack of market relevance;

b) addition of new types of fieldbuses;

c) partition of part 5 of the third edition into multiple parts numbered -5-2, -5-3, …

The text of this standard is based on the following documents:

FDIS Report on voting
65C/475/FDIS 65C/486/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.

61158-5-2 © 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 application service is provided by the application protocol making use of the services

available from the data-link or other immediately lower layer. This standard defines the

application service characteristics that fieldbus applications and/or system management may

exploit.
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 application layer service defined in this standard is a conceptual architectural
service, independent of administrative and implementation divisions.

– 8 – 61158-5-2 © IEC:2007(E)
INDUSTRIAL COMMUNICATION NETWORKS –

FIELDBUS SPECIFICATIONS –
Part 5-2: Application layer service definition – Type 2 elements

1 Scope
1.1 Overview
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 2 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 service provided by the Type 2
fieldbus application layer in terms of
a) an abstract model for defining application resources (objects) capable of being
manipulated by users via the use of the FAL service,
b) the primitive actions and events of the service;
c) the parameters associated with each primitive action and event, and the form which they
take; and
d) the interrelationship between these actions and events, and their valid sequences.
The purpose of this standard is to define the services provided to
1) the FAL user at the boundary between the user and the application layer of the fieldbus
reference model, and
2) Systems Management at the boundary between the application layer and Systems
Management of the fieldbus reference model.
This standard specifies the structure and services of the Type 2 fieldbus application layer, in

conformance with the OSI Basic Reference Model (ISO/IEC 7498) and the OSI application
layer structure (ISO/IEC 9545).
FAL services and protocols are provided by FAL application-entities (AE) contained within the
application processes. The FAL AE is composed of a set of object-oriented application service
elements (ASEs) and a layer management entity (LME) that manages the AE. The ASEs
provide communication services that operate on a set of related application process object
(APO) classes. One of the FAL ASEs is a management ASE that provides a common set of
services for the management of the instances of FAL classes.
Although these services specify, from the perspective of applications, how request and
responses are issued and delivered, they do not include a specification of what the requesting
and responding applications are to do with them. That is, the behavioral aspects of the
applications are not specified; only a definition of what requests and responses they can
send/receive is specified. This permits greater flexibility to the FAL users in standardizing

61158-5-2 © IEC:2007(E) – 9 –
such object behavior. In addition to these services, some supporting services are also defined

in this standard to provide access to the FAL to control certain aspects of its operation.

1.2 Specifications
The principal objective of this standard is to specify the characteristics of conceptual

application layer services suitable for time-critical communications, and thus supplement the

OSI Basic Reference Model in guiding the development of application layer protocols for time-

critical communications.
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 services
standardized as the various Types of IEC 61158, and the corresponding protocols
standardized in subparts of IEC 61158-6.
This specification may be used as the basis for formal application 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 standard does not specify individual implementations or products, nor does it constrain
the implementations of application layer entities within industrial automation systems.
There is no conformance of equipment to this application layer service definition standard.
Instead, conformance is achieved through implementation of conforming application layer
protocols that fulfill the Type 2 application layer services as defined in this standard.
2 Normative references
The following referenced standards 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 standard (including any amendments) applies.
IEC 60559, Binary floating-point arithmetic for microprocessor systems
IEC 61131-3:2003, Programmable controllers – Part 3: Programming languages

IEC 61158-4-2, Industrial communication networks – Fieldbus specifications – Part 4-2: Data-
link layer protocol specification – Type 2 elements
IEC 61158-6-2, Industrial communication networks – Fieldbus specifications – Part 6-2:
Application layer protocol specification – Type 2 elements
IEC 61588:2004 , Precision clock synchronization protocol for networked measurement and
control systems
IEC 61784-3-2, Industrial communications networks – Profiles – Part 3-2: Functional safety
fieldbuses – Additional specifications for CPF 2

Compliance with future editions of this standard will need checking.

– 10 – 61158-5-2 © IEC:2007(E)

ISO/IEC 646, Information technology – ISO 7–bit coded character set for information

interchange
ISO/IEC 7498-1, Information technology – Open Systems Interconnection – Basic Reference

Model – Part 1: The Basic Model

ISO/IEC 7498-3, Information technology – Open Systems Interconnection – Basic Reference

Model – Part 3: Naming and addressing

ISO/IEC 8822, Information technology – Open Systems Interconnection – Presentation

service definition
ISO/IEC 8824, Information technology – Abstract Syntax Notation One (ASN.1): Specification
of basic notation
ISO/IEC 8859-1, Information technology – 8-bit single-byte coded graphic character sets –
Part 1: Latin alphabet No. 1
ISO/IEC 9545, Information technology – Open Systems Interconnection – Application Layer
structure
ISO/IEC 10646-1, Information technology – Universal Multiple-Octet Coded Character Set
(UCS) – Architecture and Basic Multilingual Plane
ISO/IEC 10731, Information technology – Open Systems Interconnection – Basic Reference
Model – Conventions for the definition of OSI services
ISO 11898:1993 , Road vehicles – Interchange of digital information – Controller area
network (CAN) for high-speed communication
3 Terms, definitions, symbols, abbreviations and conventions
For the purposes of this document, the following terms as defined in these publications apply:
3.1 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
3.2 ISO/IEC 8822 terms
a) abstract syntax
b) presentation context
A newer edition of this standard has been published, but only the cited edition applies.

61158-5-2 © IEC:2007(E) – 11 –

3.3 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
3.4 ISO/IEC 8824 terms
a) object identifier
b) type
3.5 Type 2 fieldbus data-link layer terms
The following terms, defined in IEC 61158-3-2 and IEC 61158-4-2, apply.
a) DL-time
b) DL-scheduling-policy
c) DLCEP
d) DLC
e) DL-connection-oriented mode
f) DLPDU
g) DLSDU
h) DLSAP
i) fixed tag
j) generic tag
k) link
l) MAC ID
m) network address
n) node address
o) node
p) tag
q) scheduled
r) unscheduled
3.6 Type 2 fieldbus application-layer specific definitions
3.6.1
allocate
take a resource from a common area and assign that resource for the exclusive use of a
specific entity
3.6.2
application
function or data structure for which data is consumed or produced

– 12 – 61158-5-2 © IEC:2007(E)

3.6.3
application objects
multiple object classes that manage and provide a run time exchange of messages across the

network and within the network device

3.6.4
application process
part of a distributed application on a network, which is located on one device and

unambiguously addressed
3.6.5
application process object
component of an application process that is identifiable and accessible through an FAL
application relationship
3.6.6
application process object class
a class of application process objects defined in terms of the set of their network-accessible
attributes and services
3.6.7
application relationship
cooperative association between two or more application-entity-invocations for the purpose of
exchange of information and coordination of their joint operation. This relationship is activated
either by the exchange of application-protocol-data-units or as a result of preconfiguration
activities
3.6.8
application relationship application service element
application-service-element that provides the exclusive means for establishing and
terminating all application relationships
3.6.9
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.
3.6.10
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 behaviour of an object.
Attributes are divided into class attributes and instance attributes.
3.6.11
behaviour
indication of how an object responds to particular eventss
3.6.12
boundary clock
clock with more than a single PTP port, with each PTP port providing access to a separate
PTP communication path
NOTE  Boundary clocks are used to eliminate fluctuations produced by routers and similar network elements.

61158-5-2 © IEC:2007(E) – 13 –

3.6.13
class
a set of objects, all of which represent the same kind of system component

NOTE  A class is a generalisation of an object; a template for defining variables and methods. All objects in a

class are identical in form and behaviour, but usually contain different data in their attributes.

3.6.14
class attributes
attribute that is shared by all objects within the same class

3.6.15
class code
unique identifier assigned to each object class
3.6.16
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.
3.6.17
client
a) object which uses the services of another (server) object to perform a task
b) initiator of a message to which a server reacts
3.6.18
clock
device providing a measurement of the passage of time since a defined epoch
NOTE  There are two types of clocks in IEC 61588:2004, boundary clocks and ordinary clocks.
3.6.19
communication objects
components that manage and provide a run time exchange of messages across the network
EXAMPLES  Connection Manager object, Unconnected Message Manager (UCMM) object, and Message Router
object
3.6.20
connection
logical binding between application objects that may be within the same or different devices
NOTE 1 Connections may be either point-to-point or multipoint.
NOTE 2 The logical link between sink and source of attributes and services at different custom interfaces of RT-
Auto ASEs is referred to as interconnection. There is a distinction between data and event interconnections. The
logical link and the data flow between sink and source of automation data items is referred to as data
interconnection. The logical link and the data flow between sink (method) and source (event) of operational
services is referred to as event interconnection.
3.6.21
connection ID (CID)
identifier assigned to a transmission that is associated with a particular connection between
producers and consumers, providing a name for a specific piece of application information
3.6.22
connection path
an octet stream that defines the application object to which a connection instance applies
3.6.23
connection point
buffer which is represented as a subinstance of an Assembly object

– 14 – 61158-5-2 © IEC:2007(E)

3.6.24
consume
act of receiving data from a producer

3.6.25
consumer
node or sink that is receiving data from a producer

3.6.26
consuming application
application that consumes data

3.6.27
cyclic
repetitive in a regular manner
3.6.28
device
physical hardware connected to the link
NOTE  A device may contain more than one node.
3.6.29
device profile
a collection of device dependent information and functionality providing consistency between
similar devices of the same device type
3.6.30
end node
producing or consuming node
3.6.31
endpoint
one of the communicating entities involved in a connection
3.6.32
epoch
reference time defining the origin of a time scale
[IEC 61588:2004]
3.6.33
error
discrepancy between a computed, observed or measured value or condition and the specified
or theoretically correct value or condition
3.6.34
event
an instance of a change of conditions
3.6.35
frame
denigrated synonym for DLPDU
3.6.36
grandmaster clock
clock which serve as the primary source of time to which all others (within a collection of
IEC 61588 clocks) are ultimately synchronized.

61158-5-2 © IEC:2007(E) – 15 –

3.6.37
group
a) a general term for a collection of objects. Specific uses:

b) when describing an address, an address that identifies more than one entity

3.6.38
interface
(a) shared boundary between two functional units, defined by functional characteristics, signal

characteristics, or other characteristics as appropriate

(b) collection of FAL class attributes and services that represents a specific view on the FAL

class
3.6.39
invocation
act of using a service or other resource of an application process
NOTE  Each invocation represents a separate thread of control that may be described by its context. Once the
service completes, or use of the resource is released, the invocation ceases to exist. For service invocations, a
service that has been initiated but not yet completed is referred to as an outstanding service invocation. Also for
service invocations, an Invoke ID may be used to unambiguously identify the service invocation and differentiate it
from other outstanding service invocations.
3.6.40
instance
the actual physical occurrence of an object within a class that identifies one of many objects
within the same object class
EXAMPLE Clifornia is an instance of the object class state.
NOTE  The terms object, instance, and object instance are used to refer to a specific instance.
3.6.41
instance attributes
attribute that is unique to an object instance and not shared by the object class
3.6.42
instantiated
object that has been created in a device
3.6.43
logical device
a certain FAL class that abstracts a software component or a firmware component as an
autonomous self-contained facility of an automation device
3.6.44
Lpacket (or Link packet)
a piece of application information that contains a size, control octet, tag, and link data
NOTE  Peer data-link layers use Lpackets to send and receive service data units from higher layers in the OSI
stack.
3.6.45
manufacturer ID
identification of each product manufacturer by a unique number
3.6.46
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.

– 16 – 61158-5-2 © IEC:2007(E)

3.6.47
master clock
single clock which serves as the primary source of time within each region, and which will in

turn synchronize to other master clocks and ultimately to the grandmaster clock

NOTE  A system of IEC 61588 clocks may be segmented into regions separated by boundary clocks.

3.6.48
member
piece of an attribute that is structured as an element of an array

3.6.49
Message Router
object within a node that distributes messaging requests to appropriate application objects
3.6.50
method
a synonym for an operational service which is provided by the server ASE and
invoked by a client
3.6.51
module
hardware or logical component of a physical device
3.6.52
multipoint connection
connection from one node to many
NOTE  Multipoint connections allow messages from a single producer to be received by many consumer nodes.
3.6.53
network
a set of nodes connected by some type of communication medium, including any intervening
repeaters, bridges, routers and lower-layer gateways
3.6.54
object
abstract representation of a particular component within a device, usually a collection of
related data (in the form of variables) and methods (procedures) for operating on that data
that have clearly defined interface and behaviour
3.6.55
object specific service
service unique to the object class which defines it

3.6.56
ordinary clock
IEC 61588 clock with a single PTP port
3.6.57
originator
client responsible for establishing a connection path to the target
3.6.58
peer
role of an AR endpoint in which it is capable of acting as both client and server
3.6.59
physical device
an automation or other network device

61158-5-2 © IEC:2007(E) – 17 –

3.6.60
point-to-point connection
connection that exists between exactly two application objects

3.6.61
Precision Time Protocol (PTP)
name used for the time synchronization protocol.

3.6.62
produce
act of sending data to be received by a consumer

3.6.63
producer
node that is responsible for sending data
3.6.64
property
general term for descriptive information about an object
3.6.65
PTP message
IEC 61588 time synchronization message
NOTE  There are five designated messages types defined by IEC 61588:2004: Sync, Delay_Req, Follow-up,
Delay_Resp, and Management.
3.6.66
PTP port
logical access point for IEC 61588 communications to the clock containing the port
3.6.67
resource
a processing or information capability of a subsystem
3.6.68
serial number
a unique 32-bit integer value assigned by each manufacturer to every device having Type 2
communication capabilities
NOTE The Manufacturer ID and serial number jointly form a unique identifier for each device.
3.6.69
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
3.6.70
service
operation or function than an object and/or object class performs upon request from another
object and/or object class
3.6.71
synchronized clocks
(to a specified uncertainty) two clocks which have the same epoch and
...