ISO 14229-2:2013

INTERNATIONAL ISO
STANDARD 14229-2
First edition
2013-02-15
Road vehicles— Unified diagnostic
services (UDS) —
Part 2:
Session layer services
Véhicules routiers — Services de diagnostic unifiés (SDU) —
Partie 2: Séquence des couches de services

Reference number
©
ISO 2013
©  ISO 2013
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ii © ISO 2013 – All rights reserved

Contents Page
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and abbreviated terms . 1
3.1 Terms and definitions . 1
3.2 Abbreviated terms . 2
4 Conventions . 2
5 Document overview . 3
6 Session layer services . 4
6.1 General . 4
6.2 Specification of session layer service primitives . 6
6.3 Session data unit specification . 7
7 Timing parameter definition . 9
7.1 General application timing considerations. 9
7.2 Application timing parameter definitions – defaultSession . 10
7.3 Example for P4Server without enhanced response timing . 15
7.4 Example for P4Server with enhanced response timing . 16
7.5 Session timing parameter definitions for the non-default session . 17
7.6 Client and server timer resource requirements . 19
7.7 Error handling . 20
8 Timing handling during communication . 21
8.1 Physical communication . 21
8.2 Functional communication . 29
8.3 Minimum time between client request messages . 36
Annex A (normative) T_PDU interface . 43
Annex B (informative) Vehicle diagnostic OSI layer architecture examples . 44
B.1 Vehicle diagnostic OSI layer gateway example . 44
B.2 Vehicle diagnostic OSI layer CAN router example . 45
B.3 Vehicle diagnostic OSI layer CAN switch example . 46
Bibliography . 47

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 14229-2 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 3,
Electrical and electronic equipment.
ISO 14229 consists of the following parts, under the general title Road vehicles — Unified diagnostic services
(UDS):
 Part 1: Specification and requirements
 Part 2: Session layer services
 Part 3: Unified diagnostic services on CAN implementation (UDSonCAN)
 Part 4: Unified diagnostic services on FlexRay implementation (UDSonFR)
 Part 5: Unified diagnostic services on Internet Protocol implementation (UDSonIP)
 Part 6: Unified diagnostic services on K-Line implementation (UDSonK-Line)
The following part is under preparation:
 Part 7: Unified diagnostic services on Local Interconnect Network implementation (UDSonLIN)
The titles of future parts will be drafted as follows:
 Part n: Unified diagnostic services on … implementation (UDSon…)
iv © ISO 2013 – All rights reserved

Introduction
ISO 14229 has been established in order to define common requirements for diagnostic systems that are
independent of the underlying serial data link.
To achieve this, ISO 14229 is based on the Open Systems Interconnection (OSI) Basic Reference Model in
accordance with ISO 7498-1 and ISO/IEC 10731, which structures communication systems into seven layers.
When mapped on this model, the services used by a diagnostic tester (client) and an Electronic Control Unit
(ECU, server) are broken into the following layers in accordance with Table 1:
 Application layer (layer 7), unified diagnostic services specified in ISO 14229-1, ISO 14229-3 UDSonCAN,
ISO 14229-4 UDSonFR, ISO 14229-5 UDSonIP, ISO 14229-6 UDSonK-Line, ISO 14229-7 UDSonLIN,
further standards and ISO 27145-3 WWH-OBD.
 Presentation layer (layer 6), vehicle manufacturer specific, ISO 27145-2 WWH-OBD.
 Session layer services (layer 5) specified in this part of ISO 14229.
 Transport layer services (layer 4), specified in ISO 15765-2 DoCAN, ISO 10681-2 Communication on
FlexRay, ISO 13400-2 DoIP, ISO 27145-4 WWH-OBD.
 Network layer services (layer 3), specified in ISO 15765-2 DoCAN, ISO 10681-2 Communication on
FlexRay, ISO 13400-2 DoIP, ISO 27145-4 WWH-OBD.
 Data link layer (layer 2), specified in ISO 11898-1, ISO 11898-2, ISO 17458-2, ISO 13400-3, IEEE 802.3,
ISO 14230-2 and further standards, ISO 27145-4 WWH-OBD.
 Physical layer (layer 1), specified in ISO 11898-1, ISO 11898-2, ISO 17458-4, ISO 13400-3, IEEE 802.3,
ISO 14230-1, further standards, ISO 27145-4 WWH-OBD.
Table 1 — Example of diagnostic/programming specifications applicable to the OSI layers
OSI seven WWH-OBD
Applicability Enhanced diagnostics services
layer
ISO 14229-1, ISO 14229-3 UDSonCAN, ISO 14229-4 UDSonFR, ISO
Application
ISO 14229-5 UDSonIP, ISO 14229-6 UDSonK-Line, ISO 14229-7 27145-3
(layer 7)
UDSonLIN, further standards
Presentation ISO
vehicle manufacturer specific
(layer 6) 27145-2
Seven layer
Session
ISO 14229-2
according to
(layer 5)
ISO/IEC
Transport further
7498-1
(layer 4) standards
and
ISO ISO ISO Not
ISO/IEC
15765-2 10681-2 13400-2 applicable
Network further
(layer 3) standards
ISO
27145-4
Data link ISO ISO further
ISO ISO
(layer 2) 17458-2 14230-2 standards
11898-1, 13400-3,
ISO IEEE
Physical ISO ISO further
11898-2 802.3
(layer 1) 17458-4 14230-1 standards

vi © ISO 2013 – All rights reserved

INTERNATIONAL STANDARD ISO 14229-2:2013(E)

Road vehicles — Unified diagnostic services (UDS) — Part 2:
Session layer services
1 Scope
This part of ISO 14229 specifies data link independent requirements of session layer services.
This part of ISO 14229 specifies common session layer services to provide independence between unified
diagnostic services (ISO 14229-1) and all transport protocols and network layer services (e.g. ISO 15765-2
DoCAN, ISO 10681-2 Communication on FlexRay, ISO 13400 DoIP, ISO 14230-2 DoK-Line, etc.)
This part of ISO 14229 specifies a common service primitive interface between OSI layer 4 (Transport) and
layer 5 (Session) via so-called service request/confirmation/indication primitives. This interface allows
seamless implementation of ISO 14229-1 Unified diagnostic services (UDS) with any communication protocol
titled "DoXYZ / CoXYZ" like ISO 15765 DoCAN – Diagnostic communication over Controller Area Network,
ISO 13400 DoIP, ISO 10681 Communication over FlexRay, ISO 14230 DoK-Line.
ISO 15031 (emissions-related OBD) and ISO 27145 (WWH-OBD) support the standardized service primitive
interface.
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 14229-1, Road vehicles — Unified diagnostic services (UDS) — Part 1: Specification and requirements
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1.1
gateway
networking device that transfers the PDU on different OSI layers
EXAMPLE A network device that enables communication between control module networks that use different
communication protocols, different communication rates, etc. That includes, but is not limited to, gateway functionalities
like bridge, switch, router or application layer routing.
3.1.2
router
networking device that transfers the PDU on OSI layers 3 and 4
3.1.3
switch
networking device that transfers the PDU on OSI layer 2
3.2 Abbreviated terms
CDD common data dictionary
CMD common message dictionary
DSC diagnostic session control
ECU electronic control unit
OSI open systems interconnection
S_AE session layer address extension
S_SA session layer source address
S_Data session layer data transfer service name
SI service identifier
SOM start of message
S_Mtype session layer message type
S_PDU session layer protocol data unit
S_TA session layer target address
S_TAtype session layer target address type
4 Conventions
This part of ISO 14229 is guided by the conventions discussed in the OSI Service Conventions
(ISO 10731:1994) as they apply to the diagnostic services. These conventions specify the interactions
between the service user and the service provider. Information is passed between the service user and the
service provider by service primitives, which may convey parameters.
2 © ISO 2013 – All rights reserved

5 Document overview
Figure 1 illustrates implementations of ISO 14229-2 onto various protocols.

Figure 1 — Implementation of UDS document reference according to OSI model
6 Session layer services
6.1 General
The service interface defines a set of services that are needed to access the functions offered by the session
layer, i.e. transmission/reception of data and setting of protocol parameters.
All session layer services have the same general structure. The service primitives define how a service user
(e.g. diagnostic application) cooperates with a service provider (e.g. session layer). To define the services,
three types of service primitives are specified:
 a service request primitive S_Data.request, used by the higher application layer to pass control
information or data required to be transmitted to the session layer (i.e. the service provider is being
requested by the service user to process control information or to transmit data);
 a service indication primitive S_Data.indication, used by the session layer to pass status information and
received data to the higher application layer (i.e. the service user is being informed by the service
provider about an internal event of the session layer or the service request of a peer protocol layer entity
service user);
 a service confir
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