Road vehicles — Diagnostic communication over Controller Area Network (DoCAN) — Part 2: Transport protocol and network layer services

ISO 15765-2:2016 specifies a transport protocol and network layer services tailored to meet the requirements of CAN‑based vehicle network systems on controller area networks as specified in ISO 11898‑1. It has been defined in accordance with the diagnostic services established in ISO 14229‑1 and ISO 15031‑5 but is not limited to use with them and is also compatible with most other communication needs for in‑vehicle networks. ISO 11898‑1 specifies variable length CAN frames with a maximum payload size dependent on the protocol device used. A CLASSICAL CAN protocol device can transmit/receive frames with payload sizes ranging from 0 bytes to 8 bytes per frame. A CAN FD (flexible data rate) protocol device can transmit/receive frames with payload sizes from 0 bytes to 64 bytes. A CAN FD protocol device is also capable of transmitting/receiving CLASSICAL CAN frames. The diagnostic communication over controller area network (DoCAN) protocol supports the standardized service primitive interface as specified in ISO 14229‑2 (UDS). ISO 15765-2:2016 provides the transport protocol and network layer services to support different application-layer implementations such as - enhanced vehicle diagnostics (emissions-related system diagnostics beyond legislated functionality, non-emissions-related system diagnostics), - emissions-related on-board diagnostics (OBD) as specified in ISO 15031, - world-wide harmonized on-board diagnostics (WWH-OBD) as specified in ISO 27145, and - end of life activation on on-board pyrotechnic devices (ISO 26021). The transport protocol specifies an unconfirmed communication. NOTE This part of ISO 15765 does not determine whether CLASSICAL CAN, CAN FD or both are recommended or required to be implemented by other standards referencing this part of ISO 15765.

Véhicules routiers — Communication de diagnostic sur gest ionnaire de réseau de communication (DoCAN) — Partie 2: Protocole de transport et services de la couche réseau

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Status
Published
Publication Date
11-Apr-2016
Current Stage
9092 - International Standard to be revised
Completion Date
19-Nov-2021
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INTERNATIONAL ISO
STANDARD 15765-2
Third edition
2016-04-01
Road vehicles — Diagnostic
communication over Controller Area
Network (DoCAN) —
Part 2:
Transport protocol and network layer
services
Véhicules routiers — Communication de diagnostic sur gest ionnaire
de réseau de communication (DoCAN) —
Partie 2: Protocole de transport et services de la couche réseau
Reference number
ISO 15765-2:2016(E)
©
ISO 2016

---------------------- Page: 1 ----------------------
ISO 15765-2:2016(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2016, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2016 – All rights reserved

---------------------- Page: 2 ----------------------
ISO 15765-2:2016(E)

Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and abbreviated terms . 2
3.1 Terms and definitions . 2
3.2 Abbreviated terms . 2
4 Conventions . 3
5 Document overview. 3
6 ISO 11898-1 CAN data link layer extension . 4
6.1 CLASSICAL CAN and CAN FD frame feature comparison . 4
6.2 Illustration of CAN parameters for transport protocol and network layer services . 5
6.3 Additional requirements for CAN FD . 6
7 Network layer overview . 7
7.1 General . 7
7.2 Services provided by network layer to higher layers . 7
7.3 Internal operation of network layer . 8
8 Network layer services .10
8.1 General .10
8.2 Specification of network layer service primitives .11
8.2.1 N_USData.request .11
8.2.2 N_USData.confirm .11
8.2.3 N_USData_FF.indication .11
8.2.4 N_USData.indication .12
8.2.5 N_ChangeParameters.request .12
8.2.6 N_ChangeParameter.confirm .13
8.3 Service data unit specification .13
8.3.1 Mtype, message type .13
8.3.2 N_AI, address information .13
8.3.3 .16
8.3.4 .16
8.3.5 .16
8.3.6 .16
8.3.7 .16
8.3.8 .17
9 Transport layer protocol .18
9.1 Protocol functions .18
9.2 SingleFrame transmission .18
9.2.1 SingleFrame transmission with TX_DL = 8.18
9.2.2 SingleFrame transmission with TX_D > 8 .19
9.3 Multiple-frame transmission .19
9.4 Transport layer protocol data units .21
9.4.1 Protocol data unit types . .21
9.4.2 SF N_PDU .21
9.4.3 FF N_PDU .21
9.4.4 CF N_PDU .21
9.4.5 FC N_PDU .21
9.4.6 Protocol data unit field description .22
9.5 Transmit data link layer data length (TX_DL) configuration.22
9.5.1 Definition of TX_DL configuration values .22
9.5.2 Creating CAN frames based on N_TAtype and TX_DL .23
© ISO 2016 – All rights reserved iii

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ISO 15765-2:2016(E)

9.5.3 Verifying the correctness of received CAN frames . .23
9.5.4 Receiver determination RX_DL .25
9.6 Protocol control information specification .25
9.6.1 N_PCI .25
9.6.2 SingleFrame N_PCI parameter definition .26
9.6.3 FirstFrame N_PCI parameter definition .28
9.6.4 ConsecutiveFrame N_PCI parameter definition .29
9.6.5 FlowControl N_PCI parameter definition .30
9.7 Maximum number of FC.WAIT frame transmissions (N_WFTmax) .33
9.8 Network layer timing .33
9.8.1 Timing parameters.33
9.8.2 Network layer timeouts .37
9.8.3 Unexpected arrival of N_PDU .37
9.8.4 Wait frame error handling .39
9.9 Interleaving of messages .39
10 Data link layer usage .39
10.1 Data link layer service parameters .39
10.2 Data link layer interface services .39
10.2.1 L_Data.request .39
10.2.2 L_Data.confirm .39
10.2.3 L_Data.indication .40
10.3 Mapping of the N_PDU fields .40
10.3.1 Addressing formats .40
10.3.2 Normal addressing .40
10.3.3 Normal fixed addressing .41
10.3.4 Extended addressing .41
10.3.5 Mixed addressing.42
10.4 CAN frame data length code (DLC) .43
10.4.1 DLC parameter .43
10.4.2 CAN frame data .43
10.4.3 Data length code (DLC) error handling .45
Annex A (normative) Use of normal fixed and mixed addressing with data link layer
according to SAE J1939 .46
Annex B (normative) Reserved CAN IDs .49
Bibliography .50
iv © ISO 2016 – All rights reserved

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ISO 15765-2:2016(E)

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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical
Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 22, Road vehicles, Subcommittee SC 31, Data
communication.
This third edition cancels and replaces the second edition (ISO 15765-2:2011), which has been
technically revised.
ISO 15765 consists of the following parts, under the general title Road vehicles — Diagnostic
1)
communication over Controller Area Network (DoCAN) :
— Part 1: General information and use case definition
— Part 2: Transport protocol and network layer services
— Part 4: Requirements for emissions-related systems
1) ISO 15765-3 Implementation of unified diagnostic services (UDS on CAN) has been withdrawn and replaced
by ISO 14229-3 Road vehicles — Unified diagnostic services (UDS) — Part 3: Unified diagnostic services on CAN
implementation (UDSonCAN)
© ISO 2016 – All rights reserved v

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ISO 15765-2:2016(E)

Introduction
This part of ISO 15765 has been established in order to define common requirements for vehicle
diagnostic systems implemented on a controller area network (CAN) communication link, as specified
in ISO 11898-1. Although primarily intended for diagnostic systems, it also meets requirements from
other CAN-based systems needing a network layer protocol.
To achieve this, it is based on the Open Systems Interconnection (OSI) Basic Reference Model in
accordance with ISO/IEC 7498-1 and ISO/IEC 10731, which structures communication systems into
seven layers as shown in Table 1.
Table 1 — Enhanced and legislated on-board diagnostics specifications applicable to the OSI
layers
Vehicle-
manufacturer- Legislated OBD Legislated WWH-OBD
a
OSI 7 layers
enhanced (on-board diagnostics) (on-board diagnostics)
diagnostics
Application ISO 14229-1,
ISO 15031-5 ISO 27145-3, ISO 14229-1
(layer 7) ISO 14229-3
ISO 15031-2, ISO 27145-2, SAE 1930-DA,
ISO 15031-5, SAE J1979-DA,
Vehicle
Presentation ISO 15031-6, SAE J2012-DA,
manufacturer
(layer 6) SAE J1930-DA, SAE J1939-DA (SPNs),
specific
SAE J1979-DA, SAE J1939-73
SAE J2012-DA Appendix A (FMIs)
Session (layer 5) ISO 14229-2
Transport protocol
ISO 15765-4,
(layer 4)
ISO 15765-2 ISO 15765-2
ISO 15765-2
Network (layer 3)
ISO 15765-4,
Data link (layer 2) ISO 11898-1 ISO 11898-1
ISO 11898-1
ISO 11898-1, ISO 15765-4 ISO 27145-4
ISO 11898-2,
ISO 11898-3,
ISO 11898-1, ISO 11898-1,
Physical (layer 1) or
ISO 11898-2 ISO 11898-2
vehicle
manufacturer
specific
a
7 layers according to ISO/IEC 7498-1 and ISO/IEC 10731
The application layer services covered by ISO 14229-3 have been defined in compliance with diagnostic
services established in ISO 14229-1 and ISO 15031-5 but are not limited to use only with them.
ISO 14229-3 is also compatible with most diagnostic services defined in national standards or vehicle
manufacturer’s specifications.
For other application areas, ISO 15765 can be used with any CAN physical layer.
vi © ISO 2016 – All rights reserved

---------------------- Page: 6 ----------------------
INTERNATIONAL STANDARD ISO 15765-2:2016(E)
Road vehicles — Diagnostic communication over
Controller Area Network (DoCAN) —
Part 2:
Transport protocol and network layer services
1 Scope
This part of ISO 15765 specifies a transport protocol and network layer services tailored to meet
the requirements of CAN-based vehicle network systems on controller area networks as specified
in ISO 11898-1. It has been defined in accordance with the diagnostic services established in
ISO 14229-1 and ISO 15031-5 but is not limited to use with them and is also compatible with most other
communication needs for in-vehicle networks.
ISO 11898-1 specifies variable length CAN frames with a maximum payload size dependent on the
protocol device used. A CLASSICAL CAN protocol device can transmit/receive frames with payload
sizes ranging from 0 bytes to 8 bytes per frame. A CAN FD (flexible data rate) protocol device can
transmit/receive frames with payload sizes from 0 bytes to 64 bytes. A CAN FD protocol device is also
capable of transmitting/receiving CLASSICAL CAN frames.
The diagnostic communication over controller area network (DoCAN) protocol supports the
standardized service primitive interface as specified in ISO 14229-2 (UDS).
This part of ISO 15765 provides the transport protocol and network layer services to support different
application-layer implementations such as
— enhanced vehicle diagnostics (emissions-related system diagnostics beyond legislated functionality,
non-emissions-related system diagnostics),
— emissions-related on-board diagnostics (OBD) as specified in ISO 15031,
— world-wide harmonized on-board diagnostics (WWH-OBD) as specified in ISO 27145, and
— end of life activation on on-board pyrotechnic devices (ISO 26021).
The transport protocol specifies an unconfirmed communication.
NOTE This part of ISO 15765 does not determine whether CLASSICAL CAN, CAN FD or both are recommended
or required to be implemented by other standards referencing this part of ISO 15765.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO/IEC 7498-1, Information technology — Open Systems Interconnection — Basic Reference Model: The
Basic Model — Part 1
2)
ISO 11898-1:2015 , Road vehicles — Controller area network (CAN) — Part 1: Data link layer and physical
signalling
2) The dated reference is to the first version of ISO 11898-1 that includes the definition of CAN FD. Versions after
the dated reference are also valid. Future dated references are valid for CAN FD.
© ISO 2016 – All rights reserved 1

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ISO 15765-2:2016(E)

3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/IEC 7498-1, ISO 11898-1 and
the following apply.
3.1.1
CAN frame data length
CAN_DL
physical length of CAN frame data/payload in bytes
Note 1 to entry: See Table 3.
3.1.2
transmit data link layer data length
TX_DL
configures the maximum usable payload length in bytes of the data link layer in the transmitter for the
application that implements the network layer as defined in this part of ISO 15765
Note 1 to entry: The TX_DL is a fixed configuration value on the sender side for the PDU transmission.
3.1.3
Received data link layer data length
RX_DL
retrieved maximum usable payload length in bytes of the data link layer in the receiver for the
application that implements the network layer as defined in this part of ISO 15765
Note 1 to entry: The RX_DL value is retrieved from the FirstFrame (FF) CAN_DL of a segmented PDU and is used
to verify the correct data length of ConsecutiveFrames (CF).
3.2 Abbreviated terms
For the purposes of this part of ISO 15765, the following abbreviated terms apply.
BRS bit rate switch
BS BlockSize
CAN controller area network
CAN_DL CAN frame data link layer data length in bytes
CAN FD controller area network with flexible data rate and larger payload as defined in
ISO 11898-1
CLASSICAL CAN controller area network with static data rate and up to 8 data bytes as defined in
ISO 11898-1
CF ConsecutiveFrame
CTS continue to send
DLC CAN frame data link layer data length code
DoCAN diagnostic communication over CAN
ECU electronic control unit
FC FlowControl
FF FirstFrame
FF_DL FirstFrame data length in bytes
FMI failure mode indicator
FS FlowStatus
Mtype message type
N/A not applicable
2 © ISO 2016 – All rights reserved

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ISO 15765-2:2016(E)

N_AE network address extension
N_AI network address information
N_Ar network layer timing parameter Ar
N_As network layer timing parameter As
N_Br network layer timing parameter Br
N_Bs network layer timing parameter Bs
N_ChangeParameter network layer service name
N_Cr network layer timing parameter Cr
N_Cs network layer timing parameter Cs
N_Data network data
N_PCI network protocol control information
N_PCItype network protocol control information type
N_PDU network protocol data unit
N_SA network source address
N_SDU network service data unit
N_TA network target address
N_TAtype network target address type
N_USData network layer unacknowledged segmented data transfer service name
NW network
NWL network layer
OBD on-board diagnostics
OSI Open Systems Interconnection
PCI protocol control information
RX_DL received data link layer data length in bytes
SF SingleFrame
SF_DL SingleFrame data length in bytes
SN SequenceNumber
SPN suspect parameter number
ST SeparationTime minimum
min
TX_DL transmit data link layer data length in bytes
UDS unified diagnostic services
WWH-OBD world-wide harmonized OBD
4 Conventions
This International Standard is based on the conventions discussed in the OSI service conventions
(ISO/IEC 10731) as they apply for diagnostic services.
5 Document overview
Figure 1 illustrates the most applicable application implementations utilizing the DoCAN protocol.
© ISO 2016 – All rights reserved 3

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ISO 15765-2:2016(E)

Figure 1 — DoCAN document reference according to the OSI model
6 ISO 11898-1 CAN data link layer extension
6.1 CLASSICAL CAN and CAN FD frame feature comparison
ISO 11898-1 CLASSICAL CAN frames support payload lengths up to a maximum of 8 bytes. ISO 11898-1
CAN FD frames support payload lengths up to a maximum of 64 bytes. Therefore, the segmented
transfer of data using FirstFrame (FF), FlowControl (FC) and ConsecutiveFrame (CF) type frames
needs to be implemented with a variable configurable payload length without changing the original
protocol concept. The SF frame type has also been adapted to support the increased payload length
allowed with CAN FD frames.
4 © ISO 2016 – All rights reserved

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ISO 15765-2:2016(E)

Table 2 outlines the different features of the CAN frame types provided by ISO 11898-1.
Table 2 — CAN frame feature comparison
RefNo Feature CLASSICAL CAN CAN FD
Payload length 0.8 bytes
#1 Yes Yes
Data length code (DLC) 0.8
Payload length 8 bytes
#2 Yes No
a
Data length code (DLC) 9.15
b
Payload length 12.64 bytes
#3 No Yes
Data length code (DLC) 9.15
Different bit rates supported for the arbitration and
#4 No Yes
data phases of a CAN frame.
#5 Remote transmission request (RTR) Yes No
a
For CLASSICAL CAN, the DLC values 9.15 are automatically reduced to the value of 8 which leads to the maximum
possible CAN_DL for CLASSICAL CAN.
b
CAN FD does not support all payload lengths between 8 bytes and 64 bytes (e.g. a CAN FD frame with 10 meaningful
data bytes requires a payload length of 12 bytes); see Table 3 and 10.4.2.3.
6.2 Illustration of CAN parameters for transport protocol and network layer services
Figure 2 shows the mapping of CAN parameters onto the network/transport layer addressing
information N_AI. It illustrates the validity and applicability of network/transport layer parameters
and the resulting support of CLASSICAL CAN vs. CAN FD data link layer. Figure 2 describes this for
the example of using either normal or normal fixed addressing. For extended addressing and mixed
addressing, the concept in general also applies but the mapping of th
...

DRAFT INTERNATIONAL STANDARD
ISO/DIS 15765-2
ISO/TC 22/SC 3 Secretariat: DIN
Voting begins on: Voting terminates on:
2015-03-19 2015-06-19
Road vehicles — Diagnostic communication over
Controller Area Network (DoCAN) —
Part 2:
Transport protocol and network layer services
Véhicules routiers — Communication de diagnostic sur gest ionnaire de réseau de communication (DoCAN) —
PartieParte 2: Protocole de transport et services de la couche réseau
ICS: 43.040.15
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 15765-2:2015(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
©
PROVIDE SUPPORTING DOCUMENTATION. ISO 2015

---------------------- Page: 1 ----------------------
ISO/DIS 15765-2:2015(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2015
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested 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 2015 – All rights reserved

---------------------- Page: 2 ----------------------
ISO/DIS 15765-2
Contents Page
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and abbreviated terms . 2
3.1 Terms and definitions . 2
3.2 Abbreviated terms . 2
4 Conventions . 4
5 Document overview . 5
6 ISO 11898-1 CAN data link layer extension . 6
6.1 CLASSICAL CAN and CAN FD frame feature comparison . 6
6.2 Illustration of CAN parameters for transport protocol and network layer services . 6
6.3 Additional requirements for CAN FD . 8
7 Network layer overview . 8
7.1 General . 8
7.2 Services provided by network layer to higher layers . 8
7.3 Internal operation of network layer . 9
8 Network layer services . 10
8.1 General . 10
8.2 Specification of network layer service primitives . 11
8.3 Service data unit specification . 14
9 Transport layer protocol . 19
9.1 Protocol functions . 19
9.2 SingleFrame transmission. 19
9.3 Multiple-frame transmission . 20
9.4 Transport layer protocol data units . 22
9.5 Transmit data link layer data length (TX_DL) configuration . 24
9.6 Protocol control information specification . 27
9.7 Maximum number of FC.WAIT frame transmissions (N_WFTmax) . 36
9.8 Network layer timing . 36
9.9 Interleaving of messages. 42
10 Data link layer usage . 43
10.1 Data link layer service parameters . 43
10.2 Data link layer interface services . 43
10.3 Mapping of the N_PDU fields . 44
10.4 CAN frame data length code (DLC) . 47
Annex A (normative) Use of normal fixed and mixed addressing with data link layer according to
SAE J1939 . 50
A.1 Overview . 50
A.2 Rules . 50
Annex B (normative) Reserved CAN IDs . 53
Bibliography . 54


© ISO 2014 – All rights reserved iii

---------------------- Page: 3 ----------------------
ISO/DIS 15765-2
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 15765-2 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 3,
Electrical and electronic equipment.
This third edition cancels and replaces the second edition (ISO 15765 2:2011), of which has been technically
revised.
ISO 15765 consists of the following parts, under the general title Road vehicles — Diagnostic communication
over Controller Area Network (DoCAN):
 Part 1: General information and use case definition
 Part 2: Transport protocol and network layer services
1)
 Part 3: Implementation of unified diagnostic services (UDS on CAN)
 Part 4: Requirements for emissions-related systems

1) Document has been replaced by ISO 14229-3.
iv © ISO 2014 – All rights reserved

---------------------- Page: 4 ----------------------
ISO/DIS 15765-2
Introduction
This part of ISO 15765 has been established in order to define common requirements for vehicle diagnostic
systems implemented on a controller area network (CAN) communication link, as specified in ISO 11898.
Although primarily intended for diagnostic systems, it also meets requirements from other CAN-based
systems needing a network layer protocol.
To achieve this, it is based on the Open Systems Interconnection (OSI) Basic Reference Model in accordance
with ISO/IEC 7498-1 and ISO/IEC 10731, which structures communication systems into seven layers as
shown in Table 1.
Table 1 — Enhanced and legislated on-board diagnostics specifications applicable to the OSI layers
Vehicle-
manufacturer- Legislated OBD Legislated WWH-OBD
Applicability OSI 7 layers
enhanced (on-board diagnostics) (on-board diagnostics)
diagnostics
ISO 14229-1,
Application (layer 7) ISO 15031-5 ISO 27145-3, ISO 14229-1
ISO 14229-3
ISO 15031-2, ISO 27145-2, SAE 1930-DA,
ISO 15031-5, SAE J1979-DA, SAE J2012-
Vehicle
Presentation ISO 15031-6, DA, SAE J1939:2011,
manufacturer
(layer 6) SAE J1930-DA, Appendix C (SPN),
specific
SAE J1979-DA, SAE J1939-73:2010,
Seven layers
SAE J2012-DA Appendix A (FMI)
according to
ISO/IEC
Session (layer 5) ISO 14229-2
7498-1
Transport protocol
and
ISO 15765-4,
(layer 4)
ISO/IEC
ISO 15765-2 ISO 15765-2
ISO 15765-2
10731
Network (layer 3)
ISO ISO
Data link (layer 2) ISO 11898-1
15765-4 27145-4
ISO 11898-2
ISO 15765-4,
ISO 11898-3 ISO 11898-1,
ISO 11898-1,
ISO 11898-5 ISO 11898-2
Physical (layer 1)
ISO 11898-2
or
user defined

The application layer services covered by ISO 14229-3 have been defined in compliance with diagnostic
services established in ISO 14229-1 and ISO 15031-5, but are not limited to use only with them. ISO 14229-3
is also compatible with most diagnostic services defined in national standards or vehicle manufacturer's
specifications.
For other application areas, ISO 15765 can be used with any CAN physical layer.

© ISO 2014 – All rights reserved v

---------------------- Page: 5 ----------------------
DRAFT INTERNATIONAL STANDARD ISO/DIS 15765-2

Road vehicles — Diagnostic communication over Controller
Area Network (DoCAN) — Part 2: Transport protocol and
network layer services
1 Scope
This part of ISO 15765 specifies a transport protocol and network layer services tailored to meet the
requirements of CAN-based vehicle network systems on controller area networks as specified in ISO 11898-1.
It has been defined in accordance with the diagnostic services established in ISO 14229-1 and ISO 15031-5,
but is not limited to use with them and is also compatible with most other communication needs for in-vehicle
networks.
ISO 11898-1 specifies variable length CAN frames with a maximum payload size dependent on the protocol
device used. A CLASSICAL CAN protocol device can transmit/receive frames with payload sizes ranging from
0 to 8 bytes per frame. A CAN FD (Flexible Data Rate) protocol device can transmit/receive frames with
payload sizes from 0 to 64 bytes. A CAN FD protocol device is also capable of transmitting/receiving
CLASSICAL CAN frames.
The diagnostic communication over controller area network (DoCAN) protocol supports the standardized
service primitive interface as specified in ISO 14229-2 (UDS).
This part of ISO 15765 provides the transport protocol and network layer services to support different
application-layer implementations such as
 enhanced vehicle diagnostics (emissions-related system diagnostics beyond legislated functionality, non-
emissions-related system diagnostics),
 emissions-related on-board diagnostics (OBD) as specified in ISO 15031,
 world-wide harmonized on-board diagnostics (WWH-OBD) as specified in ISO 27145, and
 end of life activation on on-board pyrotechnic devices (ISO 26021).
The transport protocol specifies an unconfirmed communication.
NOTE ISO 15765-2 does not determine whether CLASSICAL CAN, CAN FD or both is recommended or required to
be implemented by other standards referencing this part of ISO 15765.
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/IEC 7498-1, Information technology — Open Systems Interconnection — Basic Reference Model: The
Basic Model
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ISO/DIS 15765-2
2)
ISO 11898-1:2015 Road vehicles — Controller area network (CAN) — Part 1: Data link layer and physical
signalling
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/IEC 7498-1, ISO 11898-1 and the
following apply.
3.1.1
CAN frame data length
CAN_DL
physical length of CAN frame data/payload in bytes see Table 3
3.1.2
Transmit data link layer data length
TX_DL
configures the maximum usable payload length in bytes of the data link layer in the transmitter for the
application that implements the network layer as defined in this document. The TX_DL is a fixed configuration
value on the sender side for the PDU transmission.
3.1.3
Received data link layer data length
RX_DL
retrieved maximum usable payload length in bytes of the data link layer in the receiver for the application that
implements the network layer as defined in this document. The RX_DL value is retrieved from the FirstFrame
(FF) CAN_DL of a segmented PDU and is used to verify the correct data length of Consecutive Frames (CF).
3.2 Abbreviated terms
For the purposes of this document, the following abbreviated terms apply.
BRS bit rate switch
BS BlockSize
CAN controller area network
CAN_DL CAN frame data link layer data length in bytes
CAN FD controller area network flexible data rate which supports two bit rates
CLASSICAL CAN controller area network which supports one single bit rate
CF consecutive frame
confirm confirmation service primitive
CTS continue to send
DLC CAN frame data link layer data length code

2) The dated reference is to the first version of ISO 11898-1 that includes the definition of CAN FD. Versions after the
dated reference are also valid. Future dated references are valid for CAN FD.
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ISO/DIS 15765-2
DoCAN diagnostic communication over CAN
ECU electronic control unit
FC FlowControl
FF FirstFrame
FF_DL FirstFrame data length in bytes
FMI failure mode indicator
FS FlowStatus
indication indication service primitive
Mtype message type
N/A Not applicable
N_AE network address extension
N_AI network address information
N_Ar network layer timing parameter Ar
N_As network layer timing parameter As
N_Br network layer timing parameter Br
N_Bs network layer timing parameter Bs
N_ChangeParameter network layer service name
N_Cr network layer timing parameter Cr
N_Cs network layer timing parameter Cs
N_Data network data
N_PCI network protocol control information
N_PCItype network protocol control information type
N_PDU network protocol data unit
N_SA network source address
N_SDU network service data unit
N_TA network target address
N_TAtype network target address type
N_USData network layer unacknowledged segmented data transfer service name
NW network
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ISO/DIS 15765-2
NWL network layer
OBD on-board diagnostics
OSI Open Systems Interconnection
PCI protocol control information
RX_DL received data link layer data length in bytes
SF SingleFrame
SF_DL SingleFrame data length in bytes
SN SequenceNumber
SPN suspect parameter number
ST SeparationTime minimum
min
TX_DL transmit data link layer data length in bytes
UDS unified diagnostic services
WWH-OBD world-wide harmonized OBD
4 Conventions
ISO 15765 is based on the conventions discussed in the OSI service conventions (ISO/IEC 10731) as they
apply for diagnostic services.
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ISO/DIS 15765-2
5 Document overview
Figure 1 illustrates the most applicable application implementations utilizing the DoCAN protocol.

ISO 15765-1
DoCAN
General information and
use case definition
Enhanced
Emissions-
WWH-OBD
Diagnostics
related OBD
ISO 14229-1 UDS ISO 15031-5
ISO 14229-3 ISO 27145-3
subset
Specification and Emissions-related
OSI Layer 7
UDSonCAN WWH-OBD
requirements OBD services
Application
Vehicle ISO 15031-2, -5, -6
ISO 27145-2
manufacturer Emissions-related
OSI Layer 6
WWH-OBD
specific OBD data definition
Presentation
ISO 14229-2 UDS
ISO 14229-2 UDS
Session layer 1 : 1
OSI Layer 5
Session layer services
services
Session
Standardized Service Primitive Interface
CAN diagnostic communication protocol (DoCAN)
OSI Layer 4
ISO 15765-2
Transport DoCAN
Transport
protocol
and
network
layer services
OSI Layer 3
Network
ISO 15765-4
DoCAN
ISO 11898-1 CAN
Data link layer
Requirements for
OSI Layer 2
and physical
emissions-related
Data Link
signalling
systems
ISO 11898 CAN
ISO 11898 CAN
Part 1: Data link layer and physical signalling

Part 2: High-speed medium access unit
Part 1: Data link
Part 3: Low-speed, fault-tolerant, medium-
layer and physical
OSI Layer 1
dependent interface
signalling
Physical
Part 5: High-speed medium access unit
Part 2: High-speed
with low-power mode
medium access unit

Figure 1 — DoCAN document reference according to the OSI model

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6 ISO 11898-1 CAN data link layer extension
6.1 CLASSICAL CAN and CAN FD frame feature comparison
ISO 11898-1 CLASSICAL CAN frames support payload lengths up to a maximum of 8 bytes. ISO 11898-1
CAN FD frames support payload lengths up to a maximum of 64 bytes. Therefore the segmented transfer of
data using FirstFrame (FF), FlowControl (FC) and ConsecutiveFrame (CF) type frames needs to be
implemented with a variable configurable payload length without changing the original protocol concept. The
SF frame type has also been adapted to support the increased payload length allowed with CAN FD frames.
Table 2 outlines the different features of the CAN frame types provided by ISO 11898-1.
Table 2 — CAN frame feature comparison
RefNo Feature CLASSICAL CAN CAN FD
Payload length 0.8 Bytes
#1 Yes Yes
Data Length Code (DLC) 0.8
Payload length 8 Bytes
#2 Yes No
a
Data Length Code (DLC) 9.15
b
Payload length 12.64 Bytes
#3 No Yes
Data Length Code (DLC) 9.15
Different bit rates supported for the arbitration and data
#4 No Yes
phases of a CAN frame.
#5 Remote Transmission Request (RTR) Yes No
a
For CLASSICAL CAN the DLC values 9.15 are automatically reduced to the value of 8 which leads to the maximum possible

CAN_DL for CLASSICAL CAN.
b
CAN FD does not support all payload lengths between 8 and 64 bytes (e.g. a CAN FD frame with 10 meaningful data bytes
requires a payload length of 12 bytes) see Table 3 and 10.4.2.3.

6.2 Illustration of CAN parameters for transport protocol and network layer services
Figure 2 shows the mapping of CAN parameters onto the network/transport layer addressing information
N_AI. It illustrates the validity and applicability of network/transport layer parameters and the resulting support
of CLASSICAL CAN vs. CAN FD data link layer. The figure describes this for the example of using either
normal or normal fixed addressing. For extended addressing and mixed addressing the concept in general
also applies, but the mapping of the N_AI parameter onto the CAN frame differs.

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ISO/DIS 15765-2
3
data phase
CLASSICAL CAN /
11 / 29 CAN FD /
bits BRS
1
TX CAN Frame CAN ID Format DLC D D D D . . . D D D
1 2 3 4 n-2 n-1 n
CLASSICAL
valid resulting CAN CAN FD
2
N_AI
DLC CAN_DL (n) supported supported
TX_DL = 8 2 - 8 2 - 8 yes yes
N_TA, N_SA, N_TAtype
2 – 8, 12, 16, 20,
TX_DL > 8 2 - 15 no yes
24, 32, 48, 64

Key
1 DLC value results in a CAN_DL value (n), which is the physical length of a CAN frame data/payload. In the
receiver, CAN_DL is used to determine the sender TX_DL value
2 The shown N_AI mapping is an example for normal and normal fixed addressing only.
3 The BRS (Bit Rate Switch) in the 'Format' information defines the transmission speed of the data phase.
Figure 2 — Illustration of CAN parameters for network layer services

Table 3 — CLASSICAL CAN / CAN FD data length comparison table
data length code (DLC) CLASSICAL CAN data length (CAN_DL) CAN FD data length (CAN_DL)
0 0 0
1 1 1
2 2 2
3 3 3
4 4 4
5 5 5
6 6 6
7 7 7
8 8 8
a
12
9 8
a
10 8 16
a
11 20
8
a
12 24
8
a
32
13 8
a
14 8 48
a
15 8 64
a
For CLASSICAL CAN the DLC values 9.15 are automatically reduced to the value of 8 which leads to the maximum possible
CAN_DL for CLASSICAL CAN.
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ISO/DIS 15765-2
6.3 Additional requirements for CAN FD
If a CAN FD protocol device is used this part of ISO 15765 can be configured to create either CLASSICAL
CAN or CAN FD type frames. When CAN FD type frames are enabled for the data link layer, two new options
need to be supported:
a) The BRS bit which is part of a CAN FD frame and is used to determine if the data phase is to be
transmitted at a different bit rate than the arbitration phase. The bitrate of the data phase is defined to be
equal or higher than the arbitration bitrate. Bit rate switching does not influence the transport protocol
itself (see Figure 2).
b) The maximum allowed payload length (CAN_DL, 8 . 64 bytes), see Table 3.
Accommodating different maximum payload length values requires the addition of a new configuration
variable ‘transmit data link layer data length’ (TX_DL) for the transmitting node as specified in 9.5.
The configurable TX_DL value acts as a switch and upper bound for the valid CAN frame data lengths
(CAN_DL) for the transmitting node:
 TX_DL equal to 8:
The transport protocol behaves identical to previous versions of ISO 15765 based on ISO 11898-1
(CLASSICAL CAN with 8 byte payload). See RefNo #1 in Table 2. CAN Frames created by the protocol
for transmission shall only use DLC values 2.8. This applies to both, CLASSICAL CAN and CAN FD type
frames
.
 TX_DL greater than 8:
Only ISO 11898-1 CAN FD type frames shall be used. DLC values 2.15 are allowed. See RefNo #1 and
RefNo #3 in Table 2.
7 Network layer overview
7.1 General
This part of ISO 15765 specifies an unconfirmed network layer communication protocol for the exchange of
data between network nodes, e.g. from ECU to ECU, or between external test equipment and an ECU. If the
data to be transferred does not fit into a single CAN frame, a segmentation method is provided.
In order to describe the functioning of the network layer, it is necessary to consider services provided to higher
layers and the internal operation of the network layer.
7.2 Services provided by network layer to higher layers
The service interface defines a set of services that are needed to access the functions offered by the network
layer, i.e. transmission/reception of data and setting of protocol parameters.
Two types of service are defined.
a) Communication services:
These services, of which the following are defined, enable the transfer of up to 4 294 967 295 bytes of
data.
1) N_USData.request: This service is used to request the transfer of data. If necessary, the network
layer segments the data.
2) N_USData_FF.indication: This service is used to signal the beginning of a segmented message
reception to the upper layer.
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3) N_USData.indication: This service is used to provide received data to the higher layers.
4) N_USData.confirm: This service confirms to the higher layers that the requested service has been
carried out (successfully or not).
b) Protocol parameter setting services:
These services, of which the following are defined, enable the dynamic setting of protocol parameters.
1) N_ChangeParameter.request: This service is used to request the dynamic setting of specific internal
parameters.
2) N_ChangeParameter.confirm: This service confirms to the upper layer that the request to change a
specific protocol has completed (successfully or not).
7.3 Internal operation of network layer
The internal operation of the network layer provides methods for segmentation, transmission with FlowControl,
and reassembly. The main purpose of the network layer is to transfer messages that might or might not fit in a
single CAN frame. Messages that do not fit into a single CAN frame are segmented into multiple parts, where
each can be transmitted in a CAN frame.
Figure 3 shows an example of an unsegmented message transmission.
Sender Receiver
SingleFrame (SF)

Figure 3 — Example of an unsegmented message

Figure 4 shows an example of a segmented message transmission.
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ISO/DIS 15765-2
Sender Receiver
FirstFrame
(FF)
FlowControl frame
(FC)
ConsecutiveFrame
(CF)
ConsecutiveFrame
(CF)
ConsecutiveFrame
(CF)
FlowControl frame
(FC)
ConsecutiveFrame
(CF)
ConsecutiveFrame
(CF)

Figure 4 — Example of a segmented message

FlowControl is used to adjust the sender to the network layer capabilities of the receiver. This FlowControl
scheme allows the use of diagnostic gateways and sub-networks.
8 Network layer services
8.1 General
All network layer services have the same general structure. To define the services, three types of service
primitive are specified:
 a service request primitive, used by higher communication layers or the application to pass control
information and data required to be transmitted to the network layer;
 a service indication primitive, used by the network layer to pass status information and received data to
upper communication layers or the application;
 a service confirmation primitive, used by the network layer to pass status information to higher
communication layers or the application.
This service specification does not specify an application programming interface, but only a set of service
primitives that are independent of any implementation.
All network layer services have the same general format. Service primitives are written in the form:
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service_name.type (
parameter A,
parameter B
[,parameter C, .]
)
where “service_name” is the name of the service, e.g. N_USData, “type” indicates the type of service
primitive, and “parameter A, parameter B [,parameter C, .]” are the N_SDU as a list of values passed by the
service primitive. The square brackets indicate that this part of the parameter list may be empty.
The service primitives define how a service user (e.g. diagnostic application) cooperates with a service
provider (e.g. network layer). The following service primitives are specified in this part of ISO 15765: request,
indication and confirm.
 Using the service primitive request (service_name.request), a service user requests a service from the
service provider.
 Using the service primitive indication (service_name.indication), the service provider informs a service
use
...

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