IEC 61158-6-3:2007

Industrial communication networks - Fieldbus specifications - Part 6-3: Application layer protocol specification - Type 3 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 3 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 from the previous edition deletion of the former Type 6 fieldbus for lack of market relevance; addition of new types of fieldbuses; partition of part 6 of the third edition into multiple parts numbered.

General Information

• Status: Published
• Publication Date: 13-Dec-2007
• ICS: 25.040.40 - Industrial process measurement and control
• ICS: 35.100.20 - Data link layer
• Technical Committee: SC 65C - Industrial networks
• Drafting Committee: WG 9 - TC 65/SC 65C/WG 9
• Current Stage: DELPUB - Deleted Publication
• Start Date: 06-Aug-2010
• Completion Date: 26-Oct-2025

Relations

• Replaces: IEC 61158-6:2003 - Digital data communications for measurement and control - Fieldbus for use in industrial control systems - Part 6: Application layer protocol specification
• Effective Date: 05-Sep-2023
• Replaces: IEC 61158-6:2003/COR1:2004 - Corrigendum 1 - Digital data communications for measurement and control - Fieldbus for use in industrial control systems - Part 6: Application layer protocol specification
• Effective Date: 05-Sep-2023
• Revised: IEC 61158-6-3:2010 - Industrial communication networks - Fieldbus specifications - Part 6-3: Application layer protocol specification - Type 3 elements
• Effective Date: 05-Sep-2023

Overview

IEC 61158-6-3:2007 - Industrial communication networks - Fieldbus specifications - Part 6-3: Application layer protocol specification - Type 3 elements - defines the Fieldbus Application Layer (FAL) elements used to provide application programs with access to the fieldbus communication environment. The standard describes common messaging primitives for both time‑critical and non‑time‑critical communications between automation application programs and specifies Type 3 fieldbus‑specific elements. Notable changes in this edition include removal of the former Type 6 fieldbus, addition of new fieldbus types, and the partitioning of Part 6 into multiple subparts.

Key topics and technical requirements

• FAL/APDU syntax and data types: Abstract Protocol Data Unit (APDU) structures and basic data type definitions used by application layer services.
• Transfer syntax and PDU coding: Encoding rules for Data Exchange, Parameterisation, Configuration, Diagnosis, Global Control and Clock PDUs.
• State machines: Formal specification of protocol state machines including AP-context, FAL service protocol machines (FSPMs), Application Relationship Protocol Machines (ARPMs), and DLL mapping protocol machines (DMPMs).
• Communication models: Definitions for cyclic and acyclic communication between DP‑master (class 1/2) and DP‑slave, connection establishment, and monitoring of application relationships.
• Diagnostics and parameter sets: Structures and coding for slave/master diagnosis PDUs, upload/download areas, device parameter sets and statistic counters.
• Conformance and interoperability: Requirements for conformance testing and implementation to ensure reliable operation in automation environments where missed deadlines can risk equipment, plant, or human safety.
• Safety/time‑window semantics: Clear handling of “time‑critical” messaging where specified actions must complete within defined time windows.

Applications and users

• Automation device manufacturers implementing fieldbus application layer stacks for Type 3 fieldbuses.
• Control system integrators and system architects designing deterministic industrial networks where time‑critical messaging is required.
• Firmware and protocol engineers developing DP‑master and DP‑slave implementations, diagnostic tools, and conformance tests.
• Safety engineers and plant operators evaluating application‑level communication behavior and fault propagation in process and factory automation.

Related standards

• Other parts of IEC 61158 (data link layer, physical layer, other Type specifications) for full fieldbus stack coverage.
• IEC 61784 series and IEC 61508 for functional safety and real‑time communication profiles (see applicable profiles for Type 3 mapping).

Keywords: IEC 61158-6-3, fieldbus, application layer protocol, Type 3, FAL, DP-master, DP-slave, industrial communication networks, time‑critical messaging, PDU coding, state machines.

Standards Content (Sample)

IEC 61158-6-3
Edition 1.0 2007-12
INTERNATIONAL
STANDARD
Industrial communication networks – Fieldbus specifications –
Part 6-3: Application layer protocol specification – Type 3 elements

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IEC 61158-6-3
Edition 1.0 2007-12
INTERNATIONAL
STANDARD
Industrial communication networks – Fieldbus specifications –
Part 6-3: Application layer protocol specification – Type 3 elements

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
XH
ICS 35.100.70; 25.040.40 ISBN 2-8318-9475-1

– 2 – 61158-6-3 © IEC:2007(E)
CONTENTS
FOREWORD.8

INTRODUCTION.10

1 Scope.11

1.1 General .11

1.2 Specifications .12

1.3 Conformance.12

2 Normative references.12

3 Terms, definitions, abbreviations, symbols and conventions .13
3.1 Referenced terms and definitions.13
3.2 Additional definitions.14
3.3 Abbreviations and symbols .17
3.4 Conventions .19
3.5 Conventions used in state machines .21
4 FAL syntax description.24
4.1 APDU abstract syntax.24
4.2 Data types .28
5 Transfer syntax.30
5.1 Coding of basic data types.30
5.2 Coding section related to data exchange PDUs .33
5.3 Coding section related to slave diagnosis PDUs .33
5.4 Coding section related to parameterisation PDU .44
5.5 Coding section related to configurationPDUs.50
5.6 Coding section related to global control PDUs.54
5.7 Coding section related to clock-value-PDUs .55
5.8 Coding section related to function identification and errors .56
5.9 Coding section related to master diagnosis PDU .60
5.10 Coding section related to upload/download/act para PDUs .62
5.11 Coding section related to the bus parameter set.64
5.12 Coding section related to the slave parameter set .66
5.13 Coding section related to statistic counters .70
5.14 Coding section related to set slave address PDU .70
5.15 Coding section related to initiate/abort PDUs .70
5.16 Coding section related to read/write/data transport PDUs .74

5.17 Coding section related to load region and function invocation PDUs .74
5.18 Examples of diagnosis-RES-PDUs.77
5.19 Example of Chk_Cfg-REQ-PDU .79
5.20 Examples of Chk_Cfg-REQ-PDUs with DPV1 data types .80
5.21 Example structure of the Data_Unit for Data_Exchange .81
6 FAL protocol state machines.83
6.1 Overall structure .83
6.2 Assignment of state machines to devices.84
6.3 Overview DP-slave .85
6.4 Overview DP-master (class 1).87
6.5 Overview DP-master (class 2).88
6.6 Cyclic communication between DP-master (class 1) and DP-slave .89
6.7 Acyclic communication between DP-master (class 2) and DP-master (class 1) .90
6.8 Acyclic communication between DP-master (class 1) and DP-slave.92

61158-6-3 © IEC:2007(E) – 3 –
6.9 Application relationship monitoring.94

7 AP-context state machine .99

8 FAL service protocol machines (FSPMs) .99

8.1 FSPMS.99

8.2 FSPMM1 .134

8.3 FSPMM2 .170

9 Application relationship protocol machines (ARPMs) . 189

9.1 MSCY1S.189

9.2 MSAC1S. 221

9.3 SSCY1S . 234
9.4 MSRM2S . 238
9.5 MSAC2S. 243
9.6 MSCS1S. 260
9.7 MSCY1M .262
9.8 MSAL1M.282
9.9 MSAC1M .291
9.10 MMAC1 .304
9.11 MSCS1M .311
9.12 MSAC2M .316
9.13 MMAC2 .332
10 DLL mapping protocol machines (DMPMs) . 339
10.1 DMPMS.339
10.2 DMPMM1 .353
10.3 DMPMM2 .370
11 Parameters for a DP-slave. 379
Bibliography . 380

Figure 1 – Common structure of specific fields .20
Figure 2 – Coding of the data type BinaryDate .31
Figure 3 – Encoding of TimeOfDay value.31
Figure 4 – Encoding of Time Difference value.32
Figure 5 – Encoding of Network Time value.32
Figure 6 – Encoding of Network Time Difference value .33

Figure 7 – Example Modul_Status_Array .38
Figure 8 – Example of Ext_Diag_Data in case of DPV1 diagnosis format with alarm and
status PDU.78
Figure 9 – Example of Ext_Diag_Data in case of the basic diagnosis format .79
Figure 10 – Example of a special identifier format.79
Figure 11 – Example of a special identifier format with data types.80
Figure 12 – Example of a special identifier format with data types.80
Figure 13 – Example of a empty slot with data types.81
Figure 14 – Example for multi-variable device with AI and DO function blocks.81
Figure 15 – Identifiers (ID) .82
Figure 16 – Identifier list.82
Figure 17 – Structure of the Data_Unit for the request- and response-DLPDU.82
Figure 18 – Structuring of the protocol machines and adjacent layers in a DP-slave.86

– 4 – 61158-6-3 © IEC:2007(E)
Figure 19 – Structuring of the protocol machines and adjacent layers in a DP-master

(class 1) .87

Figure 20 – Structuring of the protocol machines and adjacent layers in a DP-master

(class 2) .88

Figure 21 – Sequence of the communication between DP-master and DP-slave.90

Figure 22 – Sequence of communication between DP-master (class 2) and DP-master

(class 1) .92

Figure 23 – Sequence of acyclic communication between DP-master (class 1) and DP-

slave .94

Figure 24 – Example for connection establishment on MS2.96

Figure 25 – Idle at master-side on MS2 .97
Figure 26 – Idle at slave-side on MS2.98
Figure 27 – Example for connection establishment on MS2(server-side) . 239
Figure 28 – Structure of RM entries in the RM_Registry. 240

Table 1 – State machine description elements .21
Table 2 – Description of state machine elements .21
Table 3 – Conventions used in state machines .22
Table 4 – APDU syntax .24
Table 5 – Substitutions.27
Table 6 – Alarm_Type range .36
Table 7 – Status_Type value range .36
Table 8 – Alarm_Specifier .37
Table 9 – Range of Modul_Status_Entry (1-4).39
Table 10 – Error type .41
Table 11 – Specification of the bits Lock_Req and Unlock_Req .44
Table 12 – Range of Length_of_Manufacturer_Specific_Data if used in

Chk_Cfg-REQ-PDU .51
Table 13 – Range of Length_of_Manufacturer_Specific_Data if used in
Get_Cfg-RES-PDU .51
Table 14 – Values (codes) for data types.53
Table 15 – Specification of the bits for Un-/Sync and Un-/Freeze .54
Table 16 – Coding of the Function_Code/ Function_Num.57

Table 17 – Coding of the Error_Code / Function_Num .58
Table 18 – Values of Error_Decode .58
Table 19 – Coding of Error_Code_1 at DPV1.59
Table 20 – Values of MDiag_Identifier .60
Table 21 – Values for Area_Code_UpDownload.62
Table 22 – Values for Area_CodeActBrct.63
Table 23 – Values for Area_CodeAct.63
Table 24 – Values for Data_rate .64
Table 25 – Values for Slave_Type .67
Table 26 – Values for Alarm_Mode.68
Table 27 – Values for Subnet .73
Table 28 – Values of reason code if instance is DLL .73

61158-6-3 © IEC:2007(E) – 5 –
Table 29 – Values of reason code if instance is MS2 .73

Table 30 – Values of Extended_Function_Num.74

Table 31 – Values of FI_State .76

Table 32 – Assignment of state machines.85

Table 33 – Primitives issued by AP-Context to FSPMS .99

Table 34 – Primitives issued by FSPMS to AP-Context . 101

Table 35 – FSPMS state table .108

Table 36 – Functions used by the FSPMS . 133

Table 37 – Primitives issued by AP-Context to FSPMM1. 135
Table 38 – Primitives issued by FSPMM1 to AP-Context. 137
Table 39 – FSPMM1 state table.144
Table 40 – Functions used by the FSPMM1 . 170
Table 41 – Primitives issued by AP-Context to FSPMM2. 171
Table 42 – Primitives issued by FSPMM2 to AP-Context. 173
Table 43 – FSPMM2 state table.176
Table 44 – Functions used by the FSPMM2 . 188
Table 45 – Primitives issued by FSPMS to MSCY1S . 189
Table 46 – Primitives issued by MSCY1S to FSPMS .190
Table 47 – Rules for DPV1_Status_1, DPV1_Status_2 and DPV1_Status_3 check. 192
Table 48 – MSCY1S state table.197
Table 49 – Functions used by the MSCY1S . 219
Table 50 – Primitives issued by FSPMS to MSAC1S . 221
Table 51 – Primitives issued by MSAC1S to FSPMS . 222
Table 52 – Primitives issued by MSCY1S to MSAC1S. 222
Table 53 – Primitives issued by MSAC1S to MSCY1S. 222
Table 54 – Parameter used with primitives exchanged between MSAC1S and MSCY1S. 222
Table 55 – MSAC1S state table.224
Table 56 – Functions used by the MSAC1S . 234
Table 57 – Primitives issued by FSPMS to SSCY1S. 234
Table 58 – Primitives issued by SSCY1S to FSPMS. 235
Table 59 – SSCY1S state table .236

Table 60 – Functions used by the SSCY1S. 237
Table 61 – Primitives issued by FSPMS to MSRM2S . 238
Table 62 – Primitives issued by MSRM2S to FSPMS . 238
Table 63 – MSRM2S state table .241
Table 64 – Primitives issued by FSPMS to MSAC2S . 244
Table 65 – Primitives issued by MSAC2S to FSPMS . 245
Table 66 – Primitives issued by MSRM2S to MSAC2S . 245
Table 67 – Primitives issued by MSAC2S to MSRM2S . 246
Table 68 – Parameter used with primitives exchanged with MSAC2S . 246
Table 69 – MSAC2S state table.249
Table 70 – Primitives issued by MSCS1S to FSPMS . 261
Table 71 – MSCS1S state table.262

– 6 – 61158-6-3 © IEC:2007(E)
Table 72 – Primitives issued by FSPMM1 to MSCY1M . 263

Table 73 – Primitives issued by MSCY1M to FSPMM1 . 264

Table 74 – Parameters used with primitives exchanged between FSPMM1 and MSCY1M . 264

Table 75 – MSCY1M state table .267

Table 76 – Primitives issued by FSPMM1 to MSAL1M. 282

Table 77 – Primitives issued by MSAL1M to FSPMM1. 283

Table 78 – Primitives issued by MSCY1M to MSAL1M . 283

Table 79 – Primitives issued by MSAL1M to MSCY1M . 283

Table 80 – Parameter used with primitives exchanged between MSAL1M and MSCY1M . 283
Table 81 – Possible values in the Alarm_State_Table . 284
Table 82 – MSAL1M state table.287
Table 83 – Primitives issued by FSPMM1 to MSAC1M . 292
Table 84 – Primitives issued by MSAC1M to FSPMM1 . 292
Table 85 – Primitives issued by MSAL1M to MSAC1M . 293
Table 86 – Primitives issued by MSAC1M to MSAL1M . 293
Table 87 – Parameter used with primitives exchanged between MSAL1M and MSCY1M . 293
Table 88 – MSAC1M state table .299
Table 89 – Primitives issued by FSPMM1 to MMAC1 . 305
Table 90 – Primitives issued by MMAC1 to FSPMM1 . 305
Table 91 – MMAC1 state table.307
Table 92 – Primitives issued by FSPMM1 to MSCS1M . 312
Table 93 – Primitives issued by MSCS1M to FSPMM1 . 312
Table 94 – MSCS1M state table .314
Table 95 – Primitives issued by FSPMM2 to MSAC2M . 316
Table 96 – Primitives issued by MSAC2M to FSPMM2 . 317
Table 97 – Parameters used with primitives exchanged with MSAC2M. 317
Table 98 – MSAC2M state table .321
Table 99 – Primitives issued by FSPMM2 to MMAC2 . 332
Table 100 – Primitives issued by MMAC2 to FSPMM2 . 333
Table 101 – Parameters used with primitives exchanged with MMAC2 . 333
Table 102 – MMAC2 state table.334

Table 103 – Primitives issued by FSPMS to DMPMS . 339
Table 104 – Primitives issued by DMPMS to FSPMS . 340
Table 105 – Primitives issued by MSCY1S to DMPMS . 340
Table 106 – Primitives issued by DMPMS to MSCY1S . 341
Table 107 – Primitives issued by DMPMS to SSCY1S. 341
Table 108 – Primitives issued by MSAC1S, MSRM2S, MSAC2S to DMPMS . 342
Table 109 – Primitives issued by DMPMS to MSAC1S, MSRM2S, MSAC2S . 342
Table 110 – Primitives issued by DMPMS to MSCS1S . 342
Table 111 – Primitives issued by DMPMS to DL. 343
Table 112 – Primitives issued by DL to DMPMS.344
Table 113 – Parameters used with primitives exchanged with DMPMS. 345
Table 114 – DMPMS state table .346

61158-6-3 © IEC:2007(E) – 7 –
Table 115 – Functions used by the DMPMS. 352

Table 116 – Primitives issued by FSPMM1 to DMPMM1. 353

Table 117 – Primitives issued by DMPMM1 to FSPMM1. 354

Table 118 – Primitives issued by MSCY1M to DMPMM1 . 354

Table 119 – Primitives issued by DMPMM1 to MSCY1M . 355

Table 120 – Primitives issued by MSAL1M, MSAC1M to DMPMM1 . 355

Table 121 – Primitives issued by DMPMM1 to MSAL1M, MSAC1M . 355

Table 122 – Primitives issued by MMAC1 to DMPMM1 . 356

Table 123 – Primitives issued by DMPMM1 to MMAC1 . 356
Table 124 – Primitives issued by MSCS1M to DMPMM1 . 356
Table 125 – Primitives issued by DMPMM1 to MSCS1M . 357
Table 126 – Primitives issued by DMPMM1 to DL .357
Table 127 – Primitives issued by DL to DMPMM1 . 358
Table 128 – Parameters used with primitives exchanged with DMPMM1 . 359
Table 129 – Possible values of status. 360
Table 130 – DMPMM1 state table.361
Table 131 – Functions used by the DMPMM1 . 369
Table 132 – Primitives issued by FSPMM2 to DMPMM2. 370
Table 133 – Primitives issued by DMPMM2 to FSPMM2. 371
Table 134 – Primitives issued by MSAC2M to DMPMM2 . 371
Table 135 – Primitives issued by DMPMM2 to MSAC2M . 371
Table 136 – Primitives issued by MMAC2 to DMPMM2 . 372
Table 137 – Primitives issued by DMPMM2 to MMAC2 . 372
Table 138 – Primitives issued by DMPMM2 to DL .373
Table 139 – Primitives issued by DL to DMPMM2 . 373
Table 140 – Parameters used with primitives exchanged with DMPMM2 . 374
Table 141 – DMPMM2 state table.374
Table 142 – Functions used by DMPMM2 . 378
Table 143 – Bus parameter/reaction times for a DP-slave. 379

– 8 – 61158-6-3 © IEC:2007(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
INDUSTRIAL COMMUNICATION NETWORKS –

FIELDBUS SPECIFICATIONS –
Part 6-3: Application layer protocol specification – Type 3 elements

FOREWORD
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
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:
The following patent rights for Type 3 have been announced:
DE 36 43 979 C2 [SI] Deterministisches Zugriffsverfahren nach dem Tokenprinzip für eine
Datenübertragung
DE 36 43 979 A1 [SI] Deterministisches Zugriffsverfahren nach dem Tokenprinzip für eine
Datenübertragung
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 licenses 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:
[SI]: SIEMENS AG
Ludwig Winkel
Siemensallee 73
D-76181 Karlsruhe
Germany
61158-6-3 © IEC:2007(E) – 9 –
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 61158-6-3 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 61158-6 subseries cancel and replace

IEC 61158-6:2003. This edition of this part constitutes an editorial revision.

This edition of IEC 61158-6 includes the following significant changes from the previous

edition:
a) deletion of the former Type 6 fieldbus for lack of market relevance;
b) addition of new types of fieldbuses;
c) partition of part 6 of the third edition into multiple parts numbered -6-2, -6-3, …
The text of this standard is based on the following documents:
FDIS Report on voting
65C/476/FDIS 65C/487/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.

– 10 – 61158-6-3 © IEC:2007(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 implementors 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.

61158-6-3 © IEC:2007(E) – 11 –

INDUSTRIAL COMMUNICATION NETWORKS –

FIELDBUS SPECIFICATIONS –
Part 6-3: Application layer protocol specification – Type 3 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 3 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 3
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
1) define the wire-representation of the service primitives specified in IEC 61158-5-3, and
2) define the externally visible behavior associated with their transfer.
This standard specifies the protocol of the Type 3 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 such

– 12 – 61158-6-3 © IEC:2007(E)

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 syntax and behavior of the application

layer protocol that conveys the application layer services defined in IEC 61158-5-3.

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 parts of the IEC 61158-6 series.

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 the application layer service definition standard.
Instead, conformance is achieved through implementation of this application lay
...