ISO/DIS 15765-4

Road vehicles -- Diagnostic communication over Controller Area Network (DoCAN)

Véhicules routiers -- Diagnostic sur gestionnaire de réseau de communication (DoCAN)

Standards Content (sample)

DRAFT INTERNATIONAL STANDARD
ISO/DIS 15765-4
ISO/TC 22/SC 31 Secretariat: DIN
Voting begins on: Voting terminates on:
2020-10-08 2020-12-31
Road vehicles — Diagnostic communication over
Controller Area Network (DoCAN) —
Part 4:
Requirements for emissions-related systems

Véhicules routiers — Diagnostic sur gestionnaire de réseau de communication (DoCAN) —

Partie 4: Exigences applicables aux systèmes associés aux émissions
ICS: 43.180; 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,
This document is circulated as received from the committee secretariat.
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ISO/DIS 15765-4:2020(E)
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PROVIDE SUPPORTING DOCUMENTATION. ISO 2020
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ISO/DIS 15765-4:2020(E)
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ISO/DIS 15765-4:2020(E)
Contents Page

Foreword ..........................................................................................................................................................................................................................................v

Introduction ................................................................................................................................................................................................................................vi

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Symbols and abbreviated terms ........................................................................................................................................................... 2

4.1 Symbols ......................................................................................................................................................................................................... 2

4.2 Abbreviated terms ............................................................................................................................................................................... 3

5 Conventions ............................................................................................................................................................................................................... 3

6 Application ................................................................................................................................................................................................................. 3

6.1 Vehicle communication initialisation sequence ......................................................................................................... 3

6.1.1 OBDonUDS protocol identification .................................................................................................................. 3

6.1.2 OBDonEDS protocol identification ................................................................................................................... 3

6.1.3 Others ........................................................................................................................................................................................ 4

6.2 External test equipment communication initialisation sequence .............................................................. 4

6.3 Bit rate validation procedure ...................................................................................................................................................... 4

6.3.1 bitrateRecord ...................................................................................................................................................................... 4

6.3.2 Bit rate validation ............................................................................................................................................................ 4

6.3.3 External test equipment error detection provisions ........................................................................ 5

6.4 CAN identifier validation procedure .................................................................................................................................... 6

6.4.1 CAN identifier validation procedure OBDonEDS ................................................................................. 6

6.4.2 CAN identifier validation procedure OBDonUDS ................................................................................. 8

6.5 Support of ECUNAME reporting............................................................................................................................................10

7 Application layer (AL) ..................................................................................................................................................................................10

8 Session layer (SL) ..............................................................................................................................................................................................11

9 Transport layer (TL) ......................................................................................................................................................................................11

10 Network layer (NL) ..........................................................................................................................................................................................11

10.1 General ........................................................................................................................................................................................................11

10.2 Parameter definitions ....................................................................................................................................................................11

10.2.1 Timing parameter values .......................................................................................................................................11

10.2.2 Definition of Flow Control parameter values .......................................................................................12

10.2.3 Maximum number of regulated OBDonUDS or OBDonEDS ECUs ......................................13

10.3 Addressing formats ..........................................................................................................................................................................14

10.3.1 Normal and fixed addressing format ...........................................................................................................14

10.3.2 Functional addressing ..............................................................................................................................................14

10.3.3 Physical addressing ....................................................................................................................................................14

10.4 CAN identifier requirements ....................................................................................................................................................15

10.4.1 External test equipment .........................................................................................................................................15

10.4.2 Regulated OBDonUDS or OBDonEDS server/ECU ...........................................................................15

10.5 Mapping of diagnostic addresses .........................................................................................................................................15

10.5.1 Regulated OBDonUDS/OBDonEDS CAN identifiers .......................................................................15

10.5.2 11-bit CAN identifiers ...............................................................................................................................................16

10.5.3 29-bit CAN identifiers ...............................................................................................................................................17

11 Data link layer (DLL) .....................................................................................................................................................................................17

12 Physical layer (PHY) .......................................................................................................................................................................................18

12.1 General ........................................................................................................................................................................................................18

12.2 Bit rates ......................................................................................................................................................................................................18

12.3 CAN bit timing ......................................................................................................................................................................................18

12.3.1 Parameter values ..........................................................................................................................................................18

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ISO/DIS 15765-4:2020(E)

12.3.2 Nominal bit rate 250 kBit/s ................................................................................................................................19

12.3.3 Nominal bit rate 500 kBit/s ................................................................................................................................19

12.4 External test equipment ..............................................................................................................................................................20

12.4.1 Electrical parameters ................................................................................................................................................20

12.4.2 Cable parameters ...................................................................... ....................................................................................23

Bibliography .............................................................................................................................................................................................................................24

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ISO/DIS 15765-4:2020(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 of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/

iso/ foreword .html.

— This document was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC

31, Data communication.

— This fourth edition cancels and replaces the third edition (ISO 15765-4:2016), which has been

technically revised.
— The main changes compared to the previous edition are as follows:
— Corrected all occurrences of ⊣⫤ P2 and changed to ΔP2 ;
CAN_max CAN_max
— Clause 6 title has been changed to application;

— Subclause 6.1 title has been changed to vehicle communication initialisation sequence;

— Subclause 6.2 title has been changed to external test equipment communication initialisation

sequence;
— Changed N_As/N_Ar timeout value to 33 ms;

— Inconsistency in 10.3.3 regarding the acceptance of physically addressed request messages;

— A list of all parts in the ISO 15765 series can be found on the ISO website.

— Any feedback or questions on this document should be directed to the user’s national standards

body. A complete listing of these bodies can be found at www .iso .org/ members .html.

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ISO/DIS 15765-4:2020(E)
Introduction

This document 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 specified

[1]

in ISO/IEC 7498-1 and ISO/IEC 10731 , which structures communication systems into seven layers.

When mapped on this model, the application protocol and lower OSI layers framework requirements

specified/referenced in ISO 15765 series standard is structured according to Figure 1.

Figure 1 illustrates a standards-based documentation concept, which consists of the lower OSI layers

framework, which specifies requirements related to the transport layer, network layer, data link layer,

and physical layer standards of the OSI layers 4, 3, 2, and 1.
Figure 1 — DoCAN related OSI layers framework
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DRAFT INTERNATIONAL STANDARD ISO/DIS 15765-4:2020(E)
Road vehicles — Diagnostic communication over
Controller Area Network (DoCAN) —
Part 4:
Requirements for emissions-related systems
1 Scope

This document specifies requirements for Controller Area Networks (CAN) between the in-vehicle

network and the diagnostic link connector of the vehicle. The network presumes the use of an external

test equipment for inspection and repair diagnostics, and other possible use cases. This document

does not specify any requirements related to the in-vehicle CAN network architecture. This document

defines the requirements to enable the in-vehicle CAN network to successfully establish, maintain, and

terminate communication with the devices externally connected to the diagnostic link connector.

This document places restrictions on those International Standards for the fulfilment of the regulations.

It does not specify in-vehicle CAN bus architecture, but seeks to ensure that the vehicle's regulated CAN

communications comply with external test equipment requirements.

This document is the entry point for DoCAN (Diagnostic communication over Controller Area Network).

Based on the results of the initialisation, the external test equipment determines which protocol and

diagnostic services are supported by the vehicle’s emissions-related system.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements 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 7498-1:1994, Information technology — Open Systems Interconnection — Basic Reference Model:

The Basic Model

ISO/IEC 10731:1994, Information technology — Open Systems Interconnection — Basic Reference Model —

Conventions for the definition of OSI services

ISO 11898-1, Road vehicles — Controller area network (CAN) — Part 1: Data link layer and physical

signalling

ISO 11898-2, Road vehicles — Controller area network (CAN) — Part 2: High-speed medium access unit

ISO 14229-2, Road vehicles — Unified diagnostic services (UDS) — Part 2: Session layer services

ISO 15031-3, Road vehicles — Communication between vehicle and external equipment for emissions-

related diagnostics — Part 3: Diagnostic connector and related electrical circuits: Specification and use

ISO 15765-2, Road vehicles — Diagnostic communication over Controller Area Network (DoCAN) — Part 2:

Transport protocol and network layer services
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO/IEC 7498-1, ISO 15765,

ISO 11898 series, and the following apply.
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ISO/DIS 15765-4:2020(E)

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
on-board diagnostics on emissions diagnostic services
OBDonEDS

application protocol request and response messages defined in ISO 15031-5/SAE J1979-1 dedicated to

the diagnostics of emissions-related systems
3.2
on-board diagnostics on unified diagnostic services
OBDonUDS

application protocol request and response messages defined in ISO 14229 series and in ISO 27145-3 or

SAE J1979-2 dedicated to the diagnostics of emissions-related systems
4 Symbols and abbreviated terms
4.1 Symbols
Symbol Definition Unit
C , CAC2 capacitance of a.c. termination F
AC1
C capacitance between CAN_H and ground potential F
CAN_H
C capacitance between CAN_L and ground potential F
CAN_L
C capacitance between CAN_H and CAN_L F
DIFF
Δf oscillator tolerance Hz

l maximum cable length between diagnostic link connector and external test equipment m

CABLE

P timeout value of the client application to receive a response on a request message

2_Client_Max
P client application wait time on server response on CAN
2_CAN_Client
PropSeg propagation segment
PhaseSeg1 phase segment 1
PhaseSeg2 phase segment 2
R , R resistance of a.c. termination Ω
AC1 AC2
SyncSeg synchronization segment
t bit time µs
BIT
t receive bit time µs
BIT_RX
t transmit bit time µs
BIT_TX

t external-test-equipment cable propagation delay (without external test equipment µs

CABLE
CAN interface delay)
t nominal sample point position µs
t timing segment 1 µs
SEG1
t timing segment 2 µs
SEG2
t resynchronization jump width µs
SJW
t synchronization segment µs
SYNCSEG

t external test equipment CAN interface propagation delay (without external test µs

TOOL
equipment cable delay)
t time quantum µs
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ISO/DIS 15765-4:2020(E)
4.2 Abbreviated terms
N block size
CAN controller area networks
N consecutive frame
DID data identifier
DLC data length code
DoCAN diagnostic communication over CAN
ECU electronic control unit
ECM engine control module
N flow control
N first frame
N flow status
OBD on-board diagnostics
PID parameter identifier
N_SA source address
N single frame
SJW synchronisation jump width
SP nominal sample point
N_TA target address
TCM transmission control module
5 Conventions
This document is based on OSI service conventions as specified in ISO/IEC 10731.
6 Application
6.1 Vehicle communication initialisation sequence
6.1.1 OBDonUDS protocol identification

Vehicles that support OBDonUDS shall have ECUs that reply to the functional request service identifier

22 and DID F810 for protocol identification.
16 16
6.1.2 OBDonEDS protocol identification

Vehicles that support OBDonEDS shall have ECUs that reply to the functional request service identifier

01 and PID 00 for protocol identification.
16 16
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ISO/DIS 15765-4:2020(E)
6.1.3 Others

Vehicles that do not respond to either request (6.1.1, 6.1.2) do not support regulated OBD diagnostics

specified in this document.
6.2 External test equipment communication initialisation sequence

The external test equipment shall support the initialisation sequence specified in this document.

The purpose of the external test equipment initialisation sequence is to automatically detect, whether

the vehicle supports regulated OBDonUDS or OBDonEDS using CAN as the physical layer specified in

Clause 12.

Furthermore, the initialisation sequence determines the communication compliance status of vehicles

by analysing their responses as specified in 6.1.1 and 6.1.2.

For each regulated OBDonUDS or OBDonEDS service that requires the determination of “supported”

information, the external test equipment updates its list of expected responding ECUs prior to any data

parameter requests.

The external test equipment initialisation sequence supports single bit rate initialisation (e.g.

500 kBit/s) and multiple bit rate initialisation (e.g. 250 kBit/s and 500 kBit/s) and is separated into the

following tests:
a) 11-bit CAN identifier validation (see 6.4.1);
b) 29-bit CAN identifier validation (see 6.4.2).

The external test equipment initialisation sequence shall contain provisions for legacy vehicles using

either CAN or a non-CAN protocol on the CAN pins of the ISO 15031-3 diagnostic link connector.

6.3 Bit rate validation procedure
6.3.1 bitrateRecord
The parameter “bitrateRecord” contains the bit rates as specified in 12.2.

The bitrateRecord shall be used to specify the type of initialisation to be performed. If the bitrateRecord

parameter contains a single bit rate, then a single bit rate initialisation sequence shall be performed

using the specified single bit rate (e.g. 500 kBit/s). If the bitrateRecord parameter contains multiple bit

rates, then a multiple bit rate initialisation sequence shall be performed including a bit rate detection

procedure as defined in Figure 2.

Figure 2 shall be performed using the specified multiple bit rates (e.g. 250 kBit/s and 500 kBit/s). The

external test equipment shall use the appropriate CAN bit timing parameter values specified in 12.3.

6.3.2 Bit rate validation

If multiple bit rates are specified in the bitrateRecord parameter, the procedure as defined in Figure 2

shall be used to determine the bit rate to be used in communication with the vehicle's emissions-

related system.

The external test equipment shall set up its CAN interface using the first bit rate contained in the

bitrateRecord. It shall use the CAN bit timing parameter values specified for this bit rate (see 6.3).

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ISO/DIS 15765-4:2020(E)
Key

a Following the CAN interface setup, the external test equipment shall connect to the CAN bus and immediately

transmit a functionally addressed request message with service identifier 01 and PID "supported PIDs" using

the regulated OBDonEDS 11-bit functional request CAN identifier as defined in 10.5.2.

NOTE The immediate transmission is needed in order to activate the CAN error monitoring, since initialising

the CAN controller at the wrong bit rate without transmitting any data can leave the CAN controller in a state of

generating error frames on the CAN bus.

b The external test equipment shall check for any CAN error. If the request message is successfully transmitted

onto the CAN bus, the external test equipment shall indicate a successful transmission and proceed with the

validation of the CAN identifier as specified in 6.4.1.

c If an acknowledge (ACK) check error is detected, then the external test equipment shall continue to retry the

transmission of the request message until the N_As timeout has elapsed.

d If any other CAN error occurred, or an acknowledge check error still occurs after the N_As timeout has elapsed,

then the external test equipment shall disconnect its CAN interface from the CAN bus.

e Proceed with sequence according to Figure 3 Key 'a'.

f The external test equipment shall check whether more bit rates are contained in the bitrateRecord. If the end

of the bitrateRecord is not reached, the external test equipment shall set up its CAN interface using the next

bit rate in the bitrateRecord and restart the bit rate validation at Key 'a' in Figure 2. If no further bit rate is

contained in the bitrateRecord, it shall be assumed that the request was not transmitted successfully. This

indicates that the vehicle does not comply to this part of ISO 15765.
Figure 2 — Perform bit rate validation
6.3.3 External test equipment error detection provisions

Where the vehicle uses a CAN with a physical layer different from that specified for OBDonEDS and

OBDonUDS (see Clause 12) or a non-CAN protocol on the CAN pins of the diagnostic link connector,

the transmit procedure, specified in this document, shall guarantee that in all cases, the external test

equipment shall detect that the vehicle does not support CAN as specified for regulated OBDonUDS or

OBDonEDS and shall stop the transmission of the request message immediately.
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ISO/DIS 15765-4:2020(E)

Where the vehicle uses CAN and the physical layer in accordance with Clause 12, the transmit procedure

given as follows shall guarantee that in all cases, the external test equipment shall detect that it uses

the wrong bit rate for the transmission of the request message and shall stop disturbing the CAN bus

immediately. Under normal in-vehicle conditions (i.e. no error frames during in-vehicle communication

when the external test equipment is disconnected), the external test equipment shall disable its CAN

interface prior to the situation where the internal error counters of the regulated OBDonUDS or

OBDonEDS ECU(s) reach critical values.

To achieve this, the external test equipment shall implement the following provisions:

— possibility to immediately stop sending during transmission of any CAN frame;

— the CAN interface should be disconnected within 12 µs from reception of a bus frame error

signal. The maximum time for the disconnection is 100 µs;

— with the CAN interface disconnected, the external test equipment shall not be able to transmit

dominant bits on the CAN bus;
— possibility to immediately detect any frame error on the CAN bus.

The second provision implies that the external test equipment cannot solely rely on the usual CAN

controller error handling since it does most likely flag a frame error only after the “bus-off” state has

been reached (refer to ISO 11898-1 for further details).
6.4 CAN identifier validation procedure
6.4.1 CAN identifier validation procedure OBDonEDS

The response handling procedure shall be used to receive 11-bit CAN identifier response messages

from regulated OBDonEDS ECU(s) or to indicate that no response message has been received. If

regulated OBDonEDS-related ECUs are detected, this procedure also builds the list of available ECUs on

the regulated OBDonEDS-compliant vehicle. The response validation procedure shall be performed as

defined in Figure 3, after the 1
...