ISO 17458-1:2013

INTERNATIONAL ISO
STANDARD 17458-1
First edition
2013-02-01
Road vehicles— FlexRay
communications system —
Part 1:
General information and use case
definition
Véhicules routiers — Système de communications FlexRay —
Partie 1: Information générale et définition de cas d'utilisation

Reference number
©
ISO 2013
©  ISO 2013
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56  CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2013 – All rights reserved

Contents Page
1 Scope . 1
2 Terms, definitions, symbols and abbreviated terms . 1
2.1 Terms and definitions . 1
2.2 Abbreviated terms . 4
3 Conventions . 4
4 Document overview . 4
4.1 General . 4
4.2 Document overview and structure . 5
4.3 Open Systems Interconnection (OSI) model . 5
4.4 Document reference according to OSI model . 6
5 Use case overview and principles . 7
5.1 Basic principles for use case definition . 7
5.2 Use case clusters . 7
6 FlexRay communications system use case definition . 8
6.1 UC 1 FlexRay processes . 8
6.2 UC 2 TT modes in clusters . 11
6.3 UC 3 Communication protocol . 17
6.4 UC 4 Electrical physical layer . 20

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 17458-1 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 3,
Electrical and electronic equipment.
ISO 17458 consists of the following parts, under the general title Road vehicles — FlexRay communications
system:
 Part 1: General information and use case definition
 Part 2: Data link layer specification
 Part 3: Data link layer conformance test specification
 Part 4: Electrical physical layer specification
 Part 5: Electrical physical layer conformance test specification
iv © ISO 2013 – All rights reserved

Introduction
The FlexRay communications system is an automotive focused high speed network and was developed with
several main objectives which were defined beyond the capabilities of established standardized bus systems
like CAN and some other proprietary bus systems. Some of the basic characteristics of the FlexRay protocol
are synchronous and asynchronous frame transfer, guaranteed frame latency and jitter during synchronous
transfer, prioritization of frames during asynchronous transfer, single or multi-master clock synchronization,
time synchronization across multiple networks, error detection and signalling, and scalable fault tolerance.
The FlexRay communications system is defined for advanced automotive control applications. It serves as a
communication infrastructure for future generation high-speed control applications in vehicles by providing:
 A message exchange service that provides deterministic cycle based message transport;
 Synchronization service that provides a common time base to all nodes;
 Start-up service that provides an autonomous start-up procedure;
 Error management service that provides error handling and error signalling;
 Wakeup service that addresses the power management needs;
Since start of development the automotive industry world-wide supported the specification development. The
FlexRay communications system has been successfully implemented in production vehicles today.
The ISO 17458 series specifies the use cases, the communication protocol and physical layer requirements of
an in-vehicle communication network called "FlexRay communications system".
This part of ISO 17458 has been established in order to define the use cases for vehicle communication
systems implemented on a FlexRay data link.
To achieve this, it is based on the Open Systems Interconnection (OSI) Basic Reference Model specified in
ISO/IEC 7498-1 and ISO/IEC 10731, which structures communication systems into seven layers. When
mapped on this model, the protocol and physical layer requirements specified by ISO 17458 are broken into:
 Diagnostic services (layer 7), specified in ISO 14229-1 [3], ISO 14229-4 [5];
 Presentation layer (layer 6), vehicle manufacturer specific;
 Session layer services (layer 5), specified in ISO 14229-2 [4];
 Transport layer services (layer 4), specified in ISO 10681-2 [1];
 Network layer services (layer 3), specified in ISO 10681-2 [1];
 Data link layer (layer 2), specified in ISO 17458-2, ISO 17458-3;
 Physical layer (layer 1), specified in ISO 17458-4, ISO 17458-5;
in accordance with Table 1.
Table 1 — FlexRay communications system specifications applicable to the OSI layers
ISO 17458 FlexRay communications Vehicle manufacturer enhanced
Applicability OSI 7 layers
system diagnostics
Application (layer 7)
vehicle manufacturer specific ISO 14229-1, ISO 14229-4
Presentation (layer 6) vehicle manufacturer specific vehicle manufacturer specific
Seven layer
Session (layer 5)
vehicle manufacturer specific ISO 14229-2
according to
ISO 7498-1
Transport (layer 4)
vehicle manufacturer specific
and
ISO 10681-2
ISO/IEC
Network (layer 3)
vehicle manufacturer specific
Data link (layer 2)
ISO 17458-2, ISO 17458-3
Physical (layer 1)
ISO 17458-4, ISO 17458-5
Table 1 shows ISO 17458 Parts 2 – 5 being the common standards for the OSI layers 1 and 2 for the FlexRay
communications system and the vehicle manufacturer enhanced diagnostics.
The FlexRay communications system column shows vehicle manufacturer specific definitions for OSI layers
3 – 7.
The vehicle manufacturer enhanced diagnostics column shows application layer services covered by
ISO 14229-4 which have been defined in compliance with diagnostic services established in ISO 14229-1, but
are not limited to use only with them. ISO 14229-4 is also compatible with most diagnostic services defined in
national standards or vehicle manufacturer's specifications. The presentation layer is defined vehicle
manufacturer specific. The session layer services are covered by ISO 14229-2. The transport protocol and
network layer services are specified in ISO 10681.

vi © ISO 2013 – All rights reserved

INTERNATIONAL STANDARD ISO 17458-1:2013(E)

Road vehicles — FlexRay communications system — Part 1:
General information and use case definition
1 Scope
This part of ISO 17458 gives an overview of the structure and the partitioning of ISO 17458 and shows the
relation between the different parts. In addition, it outlines the use case scenarios where the ISO 17458 series
will be used. The terminology defined in this part of ISO 17458 is common for all FlexRay communication
systems and is used throughout all parts of ISO 17458.
2 Terms, definitions, symbols and abbreviated terms
2.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
2.1.1
active star
AS
active element which passes bus signals automatically from one input port to several output ports, where
usually a passive net is plugged to each port
NOTE1 An AS refreshes the bus signal slopes and levels; an AS does not refresh the bit-timing.
NOTE2 An AS may be implemented in a monolithic way or a non-monolithic way.
NOTE3 Optionally an AS may have a CC interface included.
2.1.2
branch
component within active star topologies
NOTE A branch can be built from a point-to-point connection, a linear bus or a passive star.
2.1.3
bus driver
BD
physical interface between the CC and the wiring harness
NOTE A BD is a mandatory FlexRay component that converts the data stream of the physical interface and supports
the node with a power mode controlling optionally.
2.1.4
cable
FlexRay transmission line.
2.1.5
cluster
communication system of multiple nodes connected via at least one communication channel directly (bus
topology), by active stars (star topology) or by a combination of bus and star connections (hybrid topologies)
NOTE Clusters can be coupled by gateways.
2.1.6
communication channel
node connection through which signals are conveyed for the purpose of communication
NOTE FlexRay allows a single CC to distribute data-frames independent from each other on two different hardware
paths or topologies. From an abstract view each path is named “communication channel” (short: "channel"). The two
channels are distinguished by using the extensions "A" and "B".
2.1.7
communication controller
CC
electronic component in a node that is responsible for implementing the protocol aspects of the FlexRay
communications system
2.1.8
communication element
symbol and frame
NOTE FlexRay distinguishes two types of communication elements which can be transmitted on the communication
channel: symbols and frames.
2.1.9
communication cycle
one complete instance of the communication structure that is periodically repeated to comprise the media
access method of the FlexRay system
NOTE The communication cycle consists of a static segment, an optional dynamic segment, an optional symbol
window, and a network idle time.
Figure 1 illustrates the segmentation of a communication cycle during FlexRay´s normal operation.
communication cycle
... ...
static dynamic symbol network
segment segment window idle time
time
Figure 1 — Segmentation of a communication cycle during normal operation

The static segment is configured into a selectable number of static slots. The segmentation in the time domain is based on
FlexRay´s distributed clock. FlexRay frames are transmitted synchronously during these static slots.
The dynamic segment is configured into mini slots. They support prioritised event driven transmission of FlexRay frames.
The symbol window is used to transmit FlexRay symbols which support e.g. wake-up of a FlexRay communication system.
The network idle time is used for clock correction.
2 © ISO 2013 – All rights reserved

2.1.10
gateway
node that is connected to two or more independent communication networks that allows information to flow
between the networks
2.1.11
host
part of an ECU where the application software is executed, separated by the CHI from the FlexRay protocol
engine
NOTE The host offers interfaces which enable the application software to control the CC and the BD.
2.1.12
hybrid topology
design of a communication cycle using various topology components
EXAMPLE An AS with one branch as point-to-point connection, one branch as linear bus and one branch as passive
star.
2.1.13
passive net
summary of all possible implementations of passive connections among FlexRay BDs and Ass
NOTE A passive summarizes all point-to-point connections, linear busses and passive stars.
2.1.14
physical layer
BDs, ASs, CC I/O stages, cables, connectors, common mode filters, ESD protection circuits, terminat
...