ISO 17356-4:2005

INTERNATIONAL ISO
STANDARD 17356-4
First edition
2005-11-01
Road vehicles — Open interface for
embedded automotive applications —
Part 4:
OSEK/VDX Communication (COM)
Véhicules routiers — Interface ouverte pour applications automobiles
embarquées —
Partie 4: Communications (COM) OSEK/VDX

Reference number
©
ISO 2005
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ii © ISO 2005 – All rights reserved

Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Interaction Layer. 1
3.1 Overview . 1
3.2 Message reception. 4
3.3 Message transmission . 7
3.4 Byte order conversion and message interpretation . 14
3.5 Deadline monitoring . 16
3.6 Notification . 21
3.7 Communication system management. 22
3.8 Functional model of the Interaction Layer .26
3.9 Interfaces . 28
4 Minimum requirements of lower communication layers . 43
5 Conformance Classes . 44
Annex A (informative) Use of ISO 17356-4 (COM) with an OS not conforming to ISO 17356-3. 46
Annex B (informative) Application notes. 47
Annex C (informative) Callouts .54

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 17356-4 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 3,
Electrical and electronic equipment.
ISO 17356 consists of the following parts, under the general title Road vehicles — Open interface for
embedded automotive applications:
⎯ Part 1: General structure and terms, definitions and abbreviated terms
⎯ Part 2: OSEK/VDX specifications for binding OS, COM and NM
⎯ Part 3: OSEK/VDX Operating System (OS)
⎯ Part 4: OSEK/VDX Communication (COM)
⎯ Part 5: OSEK/VDX Network Management (NM)
⎯ Part 6: OSEK/VDX Implementation Language (OIL)
iv © ISO 2005 – All rights reserved

Introduction
This part of ISO 17356 specifies a uniform communication environment for automotive control unit application
software. It increases the portability of application software modules by defining common software
communication interfaces and behaviour for internal communication [communication within an electronic
control unit (ECU)] and external communication (communication between networked vehicle nodes), which is
independent of the communication protocol used.
This part of ISO 17356 describes the behaviour within one ECU. It assumes that the communication
environment described in this part of ISO 17356 is used together with an operating system that conforms to
ISO 17356-3. For information on how to run the communication environment described in this part of
ISO 17356 on operating systems that do not conform to ISO 17356-3, refer to Annex A.
Requirements
The following main requirements are fulfilled by this part of ISO 17356:
General communication functionality
This part of ISO 17356 offers services to transfer data between tasks and/or interrupt service routines.
Different tasks may reside in one and the same ECU (internal communication) or in different ECUs (external
communication). Access to ISO 17356-4 services is only possible via the specified Application Program
Interface (API).
Portability, reusability and interoperability of application software
It is the aim of this part of ISO 17356 to support the portability, reusability and interoperability of application
software. The API hides the differences between internal and external communication as well as different
communication protocols, bus systems and networks.
Scalability
This part of ISO 17356 ensures that an ISO 17356-4 implementation can run on many hardware platforms.
The implementation requires only a minimum of hardware resources, therefore different levels of functionality
(conformance classes) are provided.
Support for ISO 17356-5 (Network Management-NM):
Services to support Indirect NM are provided. Direct NM has no requirements of this part of ISO 17356.
Communication concept
Figure 1 shows the conceptual model of this part of ISO 17356 and its positioning within the architecture
defined by ISO 17356. This model is presented for better understanding, but does not imply a particular
implementation of this part of ISO 17356.
Figure 1 — COM’s layer model
In this model, the scope of this part of ISO 17356 partly or entirely covers the following layers:
Interaction Layer
The Interaction Layer (IL) provides the ISO 17356-4 API which contains services for the transfer (send and
receive operations) of messages. For external communication it uses services provided by the lower layers,
whereas internal communication is handled entirely by the IL.
Network Layer
The Network Layer handles — depending on the communication protocol used — message
segmentation/recombination and acknowledgement. It provides flow control mechanisms to enable the
interfacing of communication peers featuring different levels of performance and capabilities. The Network
Layer uses services provided by the Data Link Layer. This part of ISO 17356 does not specify the Network
Layer; it merely defines minimum requirements for the Network Layer to support all features of the IL.
Data Link Layer
The Data Link Layer provides the upper layers with services for the unacknowledged transfer of individual
data packets (frames) over a network. Additionally, it provides services for the NM. This part of ISO 17356
does not specify the Data Link Layer; it merely defines minimum requirements for the Data Link Layer to
support all features of the IL.
vi © ISO 2005 – All rights reserved

Structure of this document
In the following text, the specification chapters are described briefly. Clauses 1 to 5 are normative, the
appendices are descriptive.
Clause 1: Scope
This clause describes the motivation and requirements for this part of ISO 17356, the conceptual model used
and the structure of the document.
Clause 2: Normative references
Clause 3: Interaction Layer
This clause describes the functionality of the IL of the ISO 17356-4 model and defines its API.
Clause 4: Minimum requirements of lower communication layers
This clause lists the requirements imposed by this part of ISO 17356 on the lower communication layers
(Network Layer and Data Link Layer) to support all features of the IL.
Clause 5: Conformance Classes
This clause specifies the Communication Conformance Classes, which allow the adaptation of the feature
content of ISO 17356-4 implementations to the target system’s requirements.
Annex A: Use of this part of ISO 17356 (Com) with an OS not conforming to ISO 17356-3
Annex A gives hints on how to run this part of ISO 17356 on operating systems that do not conform to
ISO 17356-3.
Annex B: Application notes
Annex B provides information on how to meet specific application requirements with the given ISO 17356-4
model.
Annex C: Callouts
Annex C supplies application examples for callouts.
INTERNATIONAL STANDARD ISO 17356-4:2005(E)

Road vehicles — Open interface for embedded automotive
applications —
Part 4:
OSEK/VDX Communication (COM)
1 Scope
This part of ISO 17356-4 (COM) specifies a uniform communication environment for automatic control unit
application software.
It increases the portability of application software modules by defining common software communication
interfaces and behaviours for internal communication (communication within an ECU) and external
communication (communication between networked vehicle nodes), which is independent of the used
communication protocol.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 17356-2, Road vehicles — Open interface for embedded automotive applications — Part 2 OSEK/VDX
specifications for binding OS, COM and NM
ISO 17356-3, Road vehicles — Open interface for embedded automotive applications — Part 3 OSEK/VDX
Operating System (OS)
ISO 17356-5, Road vehicles — Open interface for embedded automotive applications — Part 5 OSEK/VDX
Network Management (NM)
ISO 17356-6, Road vehicles — Open interface for embedded automotive applications — Part 6 OSEK/VDX
Implementation Language (OIL)
3 Interaction Layer
3.1 Overview
3.1.1 Presentation
1)
The communication in this part of ISO 17356 is based on messages . A message contains application-
specific data. Messages and message properties are configured statically via OIL (ISO 17356-6). The content
and usage of messages is not relevant to this part of ISO 17356. Messages with a length of zero (see zero-
length messages, Annex B) are allowed.

1) Messages are often called signals. Thus, COM offers a signal-based interface.
In the case of internal communication, the Interaction Layer (IL) makes the message data immediately
available to the receiver (see Figure 2). In the case of external communication, the IL packs one or more
messages into assigned Interaction Layer Protocol Data Units (I-PDU) and passes them to the underlying
layer. The functionality of internal communication is a subset of the functionality of external communication.
Internal-external communication occurs when the same message is sent internally as well as externally.
Administration of messages is done in the IL based on message objects. Message objects exist on the
sending side (sending mes
...