IEC 61158-6-17:2007

IEC 61158-6-17
Edition 1.0 2007-12
INTERNATIONAL
STANDARD
Industrial communication networks – Fieldbus specifications –
Part 6-17: Application layer protocol specification – Type 17 elements

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IEC 61158-6-17
Edition 1.0 2007-12
INTERNATIONAL
STANDARD
Industrial communication networks – Fieldbus specifications –
Part 6-17: Application layer protocol specification – Type 17 elements

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
XB
ICS 35.100.70; 25.040.40 ISBN 2-8318-9495-6

– 2 – 61158-6-17 © IEC:2007(E)
CONTENTS
FOREWORD.5
INTRODUCTION.7
1 Scope.8
1.1 General .8
1.2 Specifications.8
1.3 Conformance.8
2 Normative reference .9
3 Definitions .9
3.1 Terms and definitions .9
3.2 Abbreviations and symbols.15
3.3 Conventions .16
4 Abstract syntax description.18
4.1 FAL PDU abstract syntax .18
4.2 Abstract syntax of PDU body.18
4.3 PDUs for ASEs.20
4.4 Type definitions.23
4.5 Data types.26
5 Transfer syntax .28
5.1 Overview of encoding .28
5.2 APDU header encoding .28
5.3 APDU body encoding .29
5.4 Data type encoding rules.30
6 FAL protocol state machines structure.34
7 AP-context state machine.35
8 FAL service protocol machines (FSPMs) .35
8.1 General .35
8.2 Common parameters of the primitives .35
8.3 Variable ASE protocol machine (VARM) .36
8.4 Event ASE protocol machine (EVTM) .39
8.5 Load region ASE protocol machine (LDRM).41
8.6 Function invocation ASE protocol machine (FNIM) .43
8.7 Time ASE protocol machine (TIMM) .47
8.8 Network management ASE protocol machine (NWMM).51
9 Application relationship protocol machines (ARPMs) .55
9.1 General .55
9.2 Primitive definitions .55
9.3 State machine .56
9.4 Functions .64
10 DLL mapping protocol machine (DMPM).65
10.1 General .65
10.2 Primitive definitions .66
10.3 DMPM state machine .67
Bibliography.70

Figure 1 – APDU overview .28

61158-6-17 © IEC:2007(E) – 3 –
Figure 2 – Type field.29
Figure 3 – Identifier octet.29
Figure 4 – Length octet (one-octet format) .30
Figure 5 – Length octets (three-octet format) .30
Figure 6 – Relationships among protocol machines and adjacent layers .34
Figure 7 – State transition diagram of VARM .37
Figure 8 – State transition diagram of EVTM.40
Figure 9 – State transition diagram of LDRM.42
Figure 10 – State transition diagram of FNIM .44
Figure 11 – State transition diagram of TIMM.48
Figure 12 – State transition diagram of NWMM .52
Figure 13 – State transition diagram of the PTC-ARPM.57
Figure 14 – State transition diagram of the PTU-ARPM.59
Figure 15 – State transition diagram of the PSU-ARPM .60
Figure 16 – State transition diagram of the MTU-ARPM .62
Figure 17 – State transition diagram of the MSU-ARPM .63
Figure 18 – State transition diagram of DMPM .67

Table 1 – Conventions used for AE state machine definitions .17
Table 2 – Encoding of FalArHeader field.28
Table 3 – Primitives exchanged between FAL user and VARM.36
Table 4 – Parameters used with primitives exchanged FAL user and VARM .36
Table 5 – VARM state table – Sender transitions .37
Table 6 – VARM state table – Receiver transitions.38
Table 7 – Functions used by the VARM .39
Table 8 – Primitives exchanged between FAL user and EVTM .39
Table 9 – Parameters used with primitives exchanged FAL user and EVTM.39
Table 10 – EVTM state table – Sender transitions.40
Table 11 – EVTM state table – Receiver transitions .40
Table 12 – Functions used by the EVTM.40
Table 13 – Primitives exchanged between FAL user and LDRM.41
Table 14 – Parameters used with primitives exchanged FAL user and LDRM.41
Table 15 – LDRM state table – Sender transitions .42
Table 16 – LDRM state table – Receiver transitions .43
Table 17 – Functions used by the LDRM.43
Table 18 – Primitives exchanged between FAL user and FNIM .44
Table 19 – Parameters used with primitives exchanged FAL user and FNIM .44
Table 20 – FNIM state table – Sender transitions.45
Table 21 – FNIM state table – Receiver transitions .45
Table 22 – Functions used by the FNIM .47
Table 23 – Primitives exchanged between FAL user and TIMM.47
Table 24 – Parameters used with primitives exchanged FAL user and TIMM.47
Table 25 – TIMM states .48

– 4 – 61158-6-17 © IEC:2007(E)
Table 26 – TIMM state table – Sender transitions .49
Table 27 – TIMM state table – Receiver transitions.50
Table 28 – Functions used by the TIMM.51
Table 29 – Primitives exchanged between FAL user and NWMM .51
Table 30 – Parameters used with primitives exchanged FAL user and NWMM .52
Table 31 – NWMM states.52
Table 32 – NWMM state table – Sender transitions .53
Table 33 – NWMM state table – Receiver transitions .54
Table 34 – Functions used by the NWMM .55
Table 35 – Primitives exchanged between FSPM and ARPM .56
Table 36 – Parameters used with primitives exchanged FSPM user and ARPM .56
Table 37 – PTC-ARPM states .56
Table 38 – PTC-ARPM state table – Sender transitions .57
Table 39 – PTC-ARPM state table – Receiver transitions.58
Table 40 – PTU-ARPM states .59
Table 41 – PTU-ARPM state table – Sender transitions .59
Table 42 – PTU-ARPM state table – Receiver transitions.60
Table 43 – PSU-ARPM states .60
Table 44 – PSU-ARPM state table – Sender transitions .61
Table 45 – PSU-ARPM state table – Receiver transitions.61
Table 46 – MTU-ARPM states.62
Table 47 – MTU-ARPM state table – Sender transitions.62
Table 48 – MTU-ARPM state table – Receiver transitions .63
Table 49 – MSU-ARPM states.63
Table 50 – MSU-ARPM state table – Sender transitions.64
Table 51 – MSU-ARPM state table – Receiver transitions .64
Table 52 – Functions used by the ARPMs.65
Table 53 – Primitives exchanged between DMPM and ARPM .66
Table 54 – Primitives exchanged between data-link layer and DMPM .66
Table 55 – DMPM states.67
Table 56 – DMPM state table – Sender transitions.67
Table 57 – DMPM state table – Receiver transitions .69
Table 58 – Functions used by the DMPM .69

61158-6-17 © IEC:2007(E) – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INDUSTRIAL COMMUNICATION NETWORKS –
FIELDBUS SPECIFICATIONS –
Part 6-17: Application layer protocol specification – Type 17 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
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2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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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
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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 17:
PCT Application No. PCT/JP2004/011537 [YEC] Communication control method
PCT Application No. PCT/JP2004/011538 [YEC] Communication control method
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:
[YEC]: Yokogawa Electric Corporation
2-9-32 Nakacho, Musashino-shi, 180-8750 Tokyo,
180-8750 Tokyo,
Japan
Attention: Intellectual Property & Standardization Center
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.

– 6 – 61158-6-17 © IEC:2007(E)
International Standard IEC 61158-6-17 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 a technical addition. This part and its
Type 17 companion parts also cancel and replace IEC/PAS 62405, published in 2005.
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.

61158-6-17 © 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 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.

– 8 – 61158-6-17 © IEC:2007(E)
INDUSTRIAL COMMUNICATION NETWORKS –
FIELDBUS SPECIFICATIONS –
Part 6-17: Application layer protocol specification – Type 17 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 17 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 specifies interactions between remote applications and defines the externally
visible behavior provided by the Type 17 fieldbus application layer in terms of
a) the formal abstract syntax defining the application layer protocol data units conveyed
between communicating application entities;
b) the transfer syntax defining encoding rules that are applied to the application layer
protocol data units;
c) the application context state machine defining the application service behavior visible
between communicating application entities;
d) the application relationship state machines defining the communication behavior visible
between communicating application entities.
The purpose of this standard is to define the protocol provided to
1) define the wire-representation of the service primitives defined in IEC 61158-5-17, and
2) define the externally visible behavior associated with their transfer.
This standard specifies the protocol of the Type 17 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 61158-5-17.
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 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.

61158-6-17 © IEC:2007(E) – 9 –
Conformance is achieved through implementation of this application layer protocol
specification.
2 Normative reference
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 61158-5-17, Industrial communication networks – Fieldbus specifications - Part 5-17:
Application layer service definition – Type 17 elements
ISO/IEC 7498 (all parts), Information technology – Open Systems Interconnection – Basic
Reference Model
ISO/IEC 8824-2, Information technology – Abstract Syntax Notation One (ASN.1): Information
object specification
ISO/IEC 8825-1, Information technology – ASN.1 encoding rules: Specification of Basic
Encoding Rules (BER), Canonical Encoding Rules (CER) and Distinguished Encoding Rules
(DER)
ISO/IEC 9545, Information technology – Open Systems Interconnection – Application Layer
structure
ISO/IEC 10731, Information technology – Open Systems Interconnection – Basic Reference
Model – Conventions for the definition of OSI services

3 Definitions
For the purposes of this document, the following terms and definitions apply.
3.1 Terms and definitions
3.1.1 ISO/IEC 7498-1 terms
For the purposes of this document, the following terms as defined in ISO/IEC 7498-1 apply:
d) application entity
e) application protocol data unit
f) application service element
3.1.2 ISO/IEC 8824-2 terms
For the purposes of this document, the following terms as defined in ISO/IEC 8824 apply:
a) any type
b) bitstring type
c) Boolean type
d) choice type
e) false
f) integer type
g) null type
h) octetstring type
– 10 – 61158-6-17 © IEC:2007(E)
i) sequence of type
j) sequence type
k) simple type
l) structured type
m) tagged type
n) true
o) type
p) value
3.1.3 ISO/IEC 10731 terms
a) (N)-connection
b) (N)-entity
c) (N)-layer
d) (N)-service
e) (N)-service-access-point
f) confirm (primitive)
g) indication (primitive)
h) request (primitive)
i) response (primitive)
3.1.4 Other terms and definitions
3.1.4.1
application
function or data structure for which data is consumed or produced
3.1.4.2
application process
part of a distributed application on a network, which is located on one device and
unambiguously addressed
3.1.4.3
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
application relationship application service element
application-service-element that provides the exclusive means for establishing and
terminating all application relationships
3.1.5.1
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.
3.1.5.2
attribute
description of an externally visible characteristic or feature of an object

61158-6-17 © IEC:2007(E) – 11 –
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.
3.1.5.3
behaviour
indication of how an object responds to particular eventss
3.1.5.4
bridge
intermediate equipment that connects two or more segments using a data-link layer relay
function
3.1.5.5
channel
single physical or logical link of an input or output application object of a server to the process
3.1.5.6
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.
3.1.5.7
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
3.1.5.8
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.
3.1.5.9
connection point
buffer which is represented as a subinstance of an Assembly object
3.1.5.10
conveyance path
unidirectional flow of APDUs across an application relationship
3.1.5.11
dedicated AR
AR used directly by the FAL User
NOTE  On Dedicated ARs, only the FAL Header and the user data are transferred.
3.1.5.12
device
physical hardware connected to the link
NOTE  A device may contain more than one node.
3.1.5.13
domain
part of the RTE network consisting of one or two subnetwork(s)

– 12 – 61158-6-17 © IEC:2007(E)
NOTE Two subnetworks are required to compose a dual-redundant RTE network, and each end node in the
domain is connected to both of the subnetworks.
3.1.5.14
domain master
station which performs diagnosis of routes to all other domains, distribution of network time to
nodes inside the domain, acquisition of absolute time from the network time master and
notification of status of the domain
3.1.5.15
domain number
numeric identifier which indicates a domain
3.1.5.16
end node
producing or consuming node
3.1.5.17
endpoint
one of the communicating entities involved in a connection
3.1.5.18
error
discrepancy between a computed, observed or measured value or condition and the specified
or theoretically correct value or condition
3.1.5.19
error class
general grouping for related error definitions and corresponding error codes
3.1.5.20
external bridge
bridge to which neither internal bridges nor RTE stations are connected directly
3.1.5.21
event
an instance of a change of conditions
3.1.5.22
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
3.1.5.23
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
3.1.5.24
interface port
physical connection point of an end node, which has an independent DL-address
3.1.5.25
internal bridge
bridge to which no routers, external bridges or nodes non-compliant with this specification are
connected directly
61158-6-17 © IEC:2007(E) – 13 –
3.1.5.26
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.
3.1.5.27
junction bridge
bridge to which at least one router, external bridge or node non-compliant with this
specification, and to which at least one internal bridge or RTE station is connected
3.1.5.28
link
physical communication channel between two nodes
3.1.5.29
method
a synonym for an operational service which is provided by the server ASE and
invoked by a client
3.1.5.30
network
a set of nodes connected by some type of communication medium, including any intervening
repeaters, bridges, routers and lower-layer gateways
3.1.5.31
network time master
station which distributes network time to domain masters
3.1.5.32
node
single DL-entity as it appears on one local link
3.1.5.33
non-redundant interface node
node whch has a single interface port
3.1.5.34
non-redundant station
station that consists of a single end node
NOTE “non-redundant station” is synonymous with “end node”.
3.1.5.35
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
3.1.5.36
originator
client responsible for establishing a connection path to the target
3.1.5.37
path
logical communication channel between two nodes, which consists of one or two link(s)

– 14 – 61158-6-17 © IEC:2007(E)
3.1.5.38
peer
role of an AR endpoint in which it is capable of acting as both client and server
3.1.5.39
producer
node that is responsible for sending data
3.1.5.40
provider
source of a data connection
3.1.5.41
publisher
role of an AR endpoint that transmits APDUs onto the fieldbus for consumption by one or
more subscribers
NOTE  A publisher may not be aware of the identity or the number of subscribers and it may publish its APDUs
using a dedicated AR.
3.1.5.42
redundant interface node
node with two interface ports one of which is connected to a primary network, while the other
is connected to a secondary network
3.1.5.43
redundant station
station that consists of a pair of end nodes
NOTE Each end node of a redundant station has the same station number, but has a different DL-address.
3.1.5.44
resource
a processing or information capability of a subsystem
3.1.5.45
RTE station
station compliant with this specification
3.1.5.46
route
logical communication channel between two communication end nodes
3.1.5.47
router
intermediate equipment that connects two or more subnetworks using a network layer relay
function
3.1.5.48
segment
communication channel that connects two nodes directly without intervening bridges
3.1.5.49
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

61158-6-17 © IEC:2007(E) – 15 –
3.1.5.50
service
operation or function than an object and/or object class performs upon request from another
object and/or object class
3.1.5.51
station
end node or a pair of end nodes that perform a specific application function
3.1.5.52
station number
numeric identifier which indicates a RTE station
3.1.5.53
subnetwork
part of a network that does not contain any routers. A subnetwork consists of end nodes,
bridges and segments
NOTE  Every end node included in a subnetwork has the same IP network address.
3.1.5.54
subscriber
role of an AREP in which it receives APDUs produced by a publisher
3.2 Abbreviations and symbols
3.2.1 ISO/IEC 10731 abbreviations
ASE
application-service-element
OSI  Open Systems Interconnection
3.2.2 ISO/IEC 7498-1 abbreviations and symbols
DL- Data-link layer (as a prefix)
DLL DL-layer
DLM DL-management
DLS DL-service
DLSAP DL-service-access-point
DLSDU DL-service-data-unit
3.2.3 IEC 61158-5-17 abbreviations and symbols
AE
application entity
AL application layer
AP
application process
APDU application protocol data unit
AR
application relationship
AREP application relationship endpoint
ASN.1
abstract syntax notation one
BCD binary coded decimal
Cnf
confirmation
cnf confirmation primitive
Ev_
prefix for data types defined for event ASE
FAL fieldbus application layer
Gn_
prefix for data types defined for general use

– 16 – 61158-6-17 © IEC:2007(E)
ID identifier
IEC International Electrotechnical Commission
Ind indication
ind indication primitive
IP Internet protocol
ISO International Organization for Standardization
lsb least significant bit
msb most significant bit
PDU protocol data unit
Req request
req request primitive
Rsp response
rsp response primitive
SAP service access point
SDU service data unit
3.2.4 Other abbreviations and symbols
ARPM application relationship protocol machine
FSPM FAL service protocol machine
MSU-AR multipoint network-scheduled unconfirmed publisher/subscriber AREP
MTU-AR multipoint user-triggered unconfirmed publisher/subscriber AREP
PSU-AR point-to-point network-scheduled unconfirmed client/server AREP
PTC-AR point-to-point user-triggered confirmed client/server AREP
PTU-AR point-to-point user-triggered unconfirmed client/server AREP
3.3 Conventions
3.3.1 General conventions
This standard uses the descriptive conventions given in ISO/IEC 10731.
This standard uses the descriptive conventions given in IEC 61158-5 subseries for FAL
service definitions.
3.3.2 Conventions for APDU abstract syntax definitions
This standard uses the descriptive conventions given in ISO/IEC 8824-2 for APDU definitions.
3.3.3 Conventions for APDU transfer syntax definitions
This standard uses the descriptive conventions given in ISO/IEC 8825-1 for transfer syntax
definitions.
3.3.4 Conventions for AE state machine definitions
The conventions used for AE state machine definitions are described in Table 1.

61158-6-17 © IEC:2007(E) – 17 –
Table 1 – Conventions used for AE state machine definitions
No. Current state Event / condition => action Next state
Name of this The current Events or conditions that trigger this state The next state
transition state to which transition. after the
this state => actions in this
transition The actions that are taken when the above transition are
applies events or conditions are met. The actions are taken
always indented below events or conditions

The conventions used in the descriptions for the events, conditions and actions are as follows:
:= The value of an item on the left is replaced by the value of an item on the right. If an item
on the right is a parameter, it comes from the primitive shown as an input event.
xxx Parameter name.
Example:
Identifier := reason
means value of the ‘reason’ parameter is assigned to the parameter called
‘Identifier.’
“xxx” Indicates fixed value.
Example:
Identifier := “abc”
means value “abc” is assigned to a parameter named ‘Identifier.’

= A logical condition to indicate an item on the left is equal to an item on the right.
< A logical condition to indicate an item on the left is less than the item on the right.
> A logical condition to indicate an item on the left is greater than the item on the right.
<> A logical condition to indicate an item on the left is not equal to an item on the right.
&& Logical “AND”
|| Logical “OR”
The sequence of actions and the alternative actions can be executed using the following
reserved words.
for
endfor
if
else
elseif
The following shows examples of description using the reserved words.
Example 1:
for (Identifier := start_value to end_value)
actions
endfor
Example 2:
If (condition)
actions
else
actions
endif
– 18 – 61158-6-17 © IEC:2007(E)
4 Abstract syntax description
4.1 FAL PDU abstract syntax
4.1.1 Top level definition
FalArPDU ::=
ConfirmedSend-CommandPDU
|| ConfirmedSend-ResponsePDU
|| UnconfirmedSend-CommandPDU
4.1.2 FalArHeader
FalArHeader ::= Unsigned8{
-- bit 8-7 ProtocolVersion
-- bit 6-4 ProtocolIdentifier
-- bit 3-1 PDUIdentifier
}
4.1.3 Confirmed send service
ConfirmedSend-CommandPDU ::= SEQUENCE {
FalArHeader,
ServiceTy
...