ISO 15765-4:2005

Road vehicles — Diagnostics on Controller Area Networks (CAN) — Part 4: Requirements for emissions-related systems

ISO 15765-4:2005 specifies requirements for the emissions-related systems of legislated OBD-compliant controller area networks (CAN), such communications networks consisting of a road vehicle equipped with a single or multiple emissions-related ECUs and external test equipment. It is based on the specifications of ISO 15765-2, ISO 11898-1 and ISO 11898-2, while placing restrictions on those standards for legislated-OBD purposes. It does not specify in-vehicle CAN bus architecture. Legislated OBD-compliant vehicles are to comply with external test equipment requirements.

Véhicules routiers — Diagnostic sur gestionnaire de réseau de communication (CAN) — Partie 4: Exigences applicables aux systèmes associés aux émissions

General Information

• Status: Withdrawn
• Publication Date: 03-Jan-2005
• Withdrawal Date: 03-Jan-2005
• ICS: 43.040.15 - Car informatics. On board computer systems
• Technical Committee: ISO/TC 22 - Road vehicles
• Drafting Committee: ISO/TC 22 - Road vehicles
• Current Stage: 9599 - Withdrawal of International Standard
• Completion Date: 16-Feb-2011

Relations

• Revised: ISO 15765-4:2011 - Road vehicles — Diagnostic communication over Controller Area Network (DoCAN) — Part 4: Requirements for emissions-related systems
• Effective Date: 15-Apr-2008

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 15765-4
First edition
2005-01-15


Road vehicles — Diagnostics on
Controller Area Networks (CAN) —
Part 4:
Requirements for emissions-related
systems
Véhicules routiers — Diagnostic sur gestionnaire de réseau de
communication (CAN) —
Partie 4: Exigences applicables aux systèmes associés aux émissions




Reference number
ISO 15765-4:2005(E)
©
ISO 2005

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ISO 15765-4:2005(E)
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©  ISO 2005
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ISO 15765-4:2005(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope. 1
2 Normative references . 1
3 Terms, definitions, symbols and abbreviated terms. 1
4 External test equipment initialization sequence. 2
4.1 General. 2
4.2 11 bit CAN identifier verification procedure. 4
4.2.1 Request message transmit procedure. 4
4.2.2 Response handling procedure . 5
4.3 29 bit CAN identifier verification procedure. 7
4.3.1 Request message transmit procedure. 7
4.3.2 Response handling procedure . 8
5 Session layer . 9
6 Network layer. 10
6.1 General. 10
6.2 Addressing formats . 10
6.3 Data link layer interface. 10
6.3.1 CAN identifier requirements . 10
6.3.2 Mapping of diagnostic addresses . 10
6.4 Network layer parameters . 13
6.4.1 Network layer timing parameter values. 13
6.4.2 Definition of external test equipment network layer parameter values . 13
6.4.3 Maximum number of legislated-OBD ECUs . 14
7 Data link layer. 14
8 Physical layer . 14
8.1 General. 14
8.2 External test equipment baudrates . 14
8.3 External test equipment CAN bit timing . 15
8.3.1 CAN bit timing parameter values . 15
8.3.2 Nominal baudrate 250 kBit/s. 16
8.3.3 Nominal baudrate 500 kBit/s. 17
8.4 External test equipment . 17
8.4.1 General. 17
8.4.2 CAN interface . 18
8.4.3 External-test-equipment cable. 20
Bibliography . 21

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ISO 15765-4:2005(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.
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 15765-4 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 3,
Electrical and electronic equipment.
ISO 15765 consists of the following parts, under the general title Road vehicles — Diagnostics on Controller
Area Networks (CAN):
 Part 1: General information
 Part 2: Network layer services
 Part 3: Implementation of unified diagnostic services (UDS on CAN)
 Part 4: Requirements for emissions-related systems
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ISO 15765-4:2005(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.
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 in
ISO/IEC 7498 and ISO/IEC 10731, which structures communication systems into seven layers. When mapped
on this model, the services specified by ISO 15765 are divided into
 unified diagnostic services (layer 7), specified in ISO 15765-3,
 network layer services (layer 3), specified in ISO 15765-2,
 CAN services (layers 1 and 2), specified in ISO 11898,
in accordance with Table 1.
The application layer services covered by ISO 15765-3 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 15765-3
is also compatible with most diagnostic services defined in national standards or vehicle manufacturer's
specifications.
The network layer services covered by ISO 15765-2 have been defined to be independent of the physical
layer implemented, and a physical layer is only specified for legislated OBD.
For other application areas, ISO 15765 can be used with any CAN physical layer.
Table 1 — Enhanced and legislated-OBD diagnostic specifications applicable to the OSI layers
Open Systems Interconnection Vehicle manufacturer enhanced Legislated on-board diagnostics
(OSI) layers diagnostics (OBD)
Diagnostic application User defined ISO 15031-5
Application layer ISO 15765-3 ISO 15031-5
Presentation layer N/A N/A
Session layer ISO 15765-3 N/A
Transport layer N/A N/A
Network layer ISO 15765-2 ISO 15765-4
Data link layer ISO 11898-1 ISO 15765-4
Physical layer User defined ISO 15765-4

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INTERNATIONAL STANDARD ISO 15765-4:2005(E)

Road vehicles — Diagnostics on Controller Area Networks
(CAN) —
Part 4:
Requirements for emissions-related systems
1 Scope
This part of ISO 15765 specifies requirements for the emissions-related systems of legislated-OBD-compliant
controller area networks (CAN), such communications networks consisting of a road vehicle equipped with a
single or multiple emissions-related ECUs and external test equipment. It is based on the specifications of
ISO 15765-2, ISO 11898-1 and ISO 11898-2, while placing restrictions on those standards for legislated-OBD
purposes. It does not specify in-vehicle CAN bus architecture. Legislated-OBD-compliant vehicles are to
comply with external test equipment requirements.
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 11898 (all parts), Road vehicles — Controller area network (CAN)
1)
ISO 14229-1, Road vehicles — Unified diagnostic services (UDS) — Part 1: Specification and requirements
ISO 15765-2, Road vehicles — Diagnostics on Controller Area Networks (CAN) — Part 2: Network layer
services
ISO 15031-5, Road vehicles — Communication between vehicle and external equipment for emissions-related
1)
diagnostics — Part 5: Emissions-related diagnostic services
3 Terms, definitions, symbols and abbreviated terms
For the purposes of this document, the terms and definitions given in ISO 14229-1 and the following symbols
and abbreviated terms apply.
C , C capacitance of a.c. termination
1 2
C capacitance between CAN_H and ground potential
CAN_H
C capacitance between CAN_L and ground potential
CAN_L
C capacitance between CAN_H and CAN_L
DIFF


1) To be published.
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ISO 15765-4:2005(E)
L max. cable length between OBD connector and external test equipment
CABLE
R , R resistance of a.c. termination
1 2
t timing segment 1
SEG1
t timing segment 2
SEG2
t synchronization segment
SYNCSEG
t bit time
BIT
t receive bit time
BIT_RX
t transmit bit time
BIT_TX
t external test equipment CAN interface propagation delay (without external test
TOOL
equipment cable delay)
t external-test-equipment cable propagation delay (without external test equipment
CABLE
CAN interface delay)
t time quantum
Q
∆f oscillator tolerance
ECU electronic control unit
OBD on-board diagnostics
Prop_Seg propagation segment
Phase_Seg1 phase segment 1
Phase_Seg2 phase segment 2
SA source address
SJW synchronization jump width
SP nominal sample point
Sync_Seg synchronization segment
TA target address
4 External test equipment initialization sequence
4.1 General
The external test equipment shall support the initialization sequence specified in this part of ISO 15765. See
Figure 1.
The purpose of the external test equipment initialization sequence is to automatically detect whether the
vehicle supports legislated on-board diagnostics on CAN using the physical layer specified in Clause 8.
Furthermore, the initialization sequence determines the legislated-OBD ECUs (CAN Id, see 6.3) expected to
respond to ISO 15031-5 service 01 hex requests. Note that for each legislated-OBD service that requires the
determination of “supported” information, the external test equipment has to update its list of expected
responding legislated-OBD ECUs prior to any data parameter requests (see ISO 15031-5 for applicable
services). The external test equipment initialization sequence supports single baudrate initialization (e.g.
500 kBit/s) and multiple baudrate initialization (e.g. 250 kBit/s and 500 kBit/s) and is separated into
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ISO 15765-4:2005(E)
a) 11 bit CAN identifier verification procedure (see 4.2), and
b) 29 bit CAN identifier verification procedure (see 4.3).
The external test equipment initialization sequence contains provisions for legacy vehicles using either CAN
(same or different physical layer as defined for legislated OBD) or a different protocol (non-CAN) on the CAN
pins of the ISO 15031-3 diagnostic connector.

Figure 1 — Initialization sequence — Overview
The parameter baudrateRecord shall be used to specify the type of initialization to be performed. If the
baudrateRecord parameter contains a single baudrate, then a single baudrate initialization sequence shall be
performed using the specified single baudrate (e.g. 500 kBit/s). If the baudrateRecord parameter contains
multiple baudrates, then a multiple baudrate initialization sequence including a baudrate detection procedure
shall be performed using the specified multiple baudrates (e.g. 250 kBit/s and 500 kBit/s).
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ISO 15765-4:2005(E)
By default the baudrateRecord contains all baudrates specified in 8.3. The default content of the parameter
baudrateRecord can be superseded by any other list of baudrates, e.g. single 500 kBit/s baudrate as specified
in 8.3.3.
For legislated-OBD baudrates, the external test equipment shall use the appropriate CAN bit timing parameter
values defined in 8.3.
The following descriptions of the external test equipment initialization make use of the connectors A to F as
shown in Figure 1 to reference certain entry and exit points.
4.2 11 bit CAN identifier verification procedure
4.2.1 Request message transmit procedure
The purpose of the 11 bit CAN identifier verification procedure is to determine whether 11 bit CAN identifiers
are being used in legislated-OBD communication and, if multiple baudrates are specified in the
baudrateRecord parameter, to determine the baudrate to be used in such communication.
The following transmit procedure shall be used to transmit the request message of the 11 bit CAN identifier
verification procedure. The transmit procedure contains provisions for legacy vehicles which use either CAN
(same or different physical layer as defined for legislated OBD) or a different protocol (non CAN) on the CAN
pins of the ISO 15031-3 diagnostic connector.
Where the vehicle uses a CAN with a physical layer different from that specified for legislated OBD (Clause 8)
or a non-CAN protocol on the CAN pins of the OBD connector, the transmit procedure given as follows shall
guarantee that in all cases the external test equipment will detect that the vehicle does not support CAN as
specified for legislated OBD and will stop the transmission of the request message immediately.
Where the vehicle uses CAN and the physical layer according to Clause 8, the transmit procedure given as
follows shall guarantee that in all cases the external test equipment will detect that it uses the wrong baudrate
for the transmission of the request message and will 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 will disable its CAN interface prior to the situation where the
internal error counters of the OBD ECU(s) reach critical values.
To achieve this, the external test equipment shall support the following features.
 Possibility to stop sending immediately during transmission of any CAN frame. The CAN interface should
be disconnected within 12 µs from reception of a bus 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 error on the CAN bus.
The procedure shall be performed as follows. See Figure 2.
a) The external test equipment shall set up its CAN interface using the first baudrate contained in the
baudrateRecord. It shall use the CAN bit timing parameter values defined for this baudrate (see 8.3).
Following the CAN Interface set-up, it shall connect the CAN Interface to the CAN bus.
b) The external test equipment shall transmit a functionally addressed service 01 hex request message
2)
(read-supported PIDs) using the legislated-OBD 11 bit functional request CAN identifier according to
6.3.2.2.


2) See ISO 15031-5 for the request message definition of service 01 hex to read the supported PIDs.
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ISO 15765-4:2005(E)
c) The external test equipment shall check for any CAN error. If the request message is transmitted onto the
CAN bus, it shall indicate a successful transmission (connector B).
d) If a CAN error occurred, the external test equipment shall disconnect its CAN Interface from the CAN bus.
With a disconnected CAN interface, the external test equipment shall not be able to transmit dominant
bits on the CAN bus. It shall check whether more baudrates are contained in the baudrateRecord. If no
further baudrate is contained in the baudrateRecord, it shall indicate that the request was not transmitted
successfully (connector F).
e) If the end of the baudrateRecord is not reached, the external test equipment shall set up its CAN interface
using the next baudrate in the baudrateRecord and shall connect its CAN interface to the CAN bus.
Following the setup, the external test equipment shall transmit the request message once again [continue
from b)].

Figure 2 — Initialization sequence — 11 bit CAN identifier request transmission
4.2.2 Response handling procedure
The response handling procedure shall be used to receive 11 bit CAN identifier response messages and
indicates that no response message has been received. It shall be performed immediately after the 11 bit
CAN identifier request message transmit procedure (4.2.1), as follows. See Figure 3.
a) If the transmission of the request message was successful (connector B), the external test equipment
shall start the P2 (see ISO 15031-5) application timer.
CAN
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ISO 15765-4:2005(E)
b) If the external test equipment determines a P2 timeout then no response message has been started
CAN
and the external test equipment has verified that 11 bit CAN identifiers are not used for legislated-OBD
communication (connector C). In addition, this means that the external test equipment has determined
that the vehicle supports CAN using the specified physical layer and one of the baudrates contained in
the baudrateRecord parameter.

Figure 3 — Initialization sequence — 11 bit CAN identifier response handling
c) The start of a response message can either be the reception of a FirstFrame or SingleFrame which uses
one of the specified legislated-OBD 11 bit physical response CAN identifiers (see 6.3.2.2).
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ISO 15765-4:2005(E)
d) If at least one response message is started, the external test equipment shall continue to receive this
previously started response message (only applies to multiple-frame response messages) and shall
accept further response messages within P2 which use one of the specified legislated-OBD 11 bit
CAN
physical response CAN identifiers.
e) When all started response messages are completely received (positive or negative responses) and the
P2 application timer is timed out, this means that the external test equipment has verified that the
CAN
vehicle supports legislated OBD on CAN using 11 bit CAN identifiers (connector E). If all received
response messages are positive response messages, then the external test equipment knows the
supported PIDs and the communication parameters of the legislated-OBD ECUs expected to respond to
service 01 hex data parameter requests. Where one or more of the received response messages are
negative response messages with response code 21 hex (busyRepeatRequest), the external test
equipment shall start the initialization sequence (Connector A) again after a minimum delay of 200 ms. If
the negative response(s) appear(s) on six (6) subsequent sequences, the external test equipment will
assume that the vehicle is not compliant with ISO 15765-4 (connector F). This means that the legislated
OBD-related ECU(s) shall provide a positive response within a maximum of five retries.
4.3 29 bit CAN identifier verification procedure
4.3.1 Request message transmit procedure
The purpose of the 29 bit CAN identifier verification procedure is to determine whether 29 bit CAN identifiers
are being used in legislated-OBD communication.
The 29 bit CAN identifier request message transmit procedure shall be used to transmit the functionally
addressed request message of the 29 bit CAN identifier verification procedure. The same requirements as
specified in 4.2.1 apply to the external test equipment when transmitting this request message. The procedure
shall be performed as follows. See Figure 4.

Figure 4 — Initialization sequence — 29 bit CAN identifier request transmission
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ISO 15765-4:2005(E)
a) If the external test equipment reaches this point in the initialization sequence, this means that the CAN
baudrate is already configured based on the previously performed 11 bit CAN identifier verification
procedure. The external test equipment shall transmit a functionally addressed service 01 hex request
message (read-supported PIDs — see ISO 15031-5) using the legislated-OBD 29 bit functional request
CAN identifier according to 6.3.2.3. There is no need to set up the CAN Interface.
b) The external test equipment shall check for any CAN error. If the request message is transmitted onto the
CAN bus, it shall indicate a successful transmission (connector D). If a CAN error occurred, the external
test equipment shall disconnect its CAN Interface from the CAN bus — with a disconnected CAN
interface, the external test equipment shall not be able to transmit dominant bits on the CAN bus — and
shall indicate a transmit error (connector F).
4.3.2 Response handling procedure
The 29 bit CAN identifier response handling procedure shall be used to receive 29 bit CAN identifier response
messages and indicates that no response message has been received. It shall be performed immediately
after the 29 bit CAN identifier request message transmit procedure (4.3.1), as follows. See Figure 5.
a) If the transmission of the request message was successful (connector D) then the external test
equipment shall start the P2 (see ISO 15031-5) application timer.
CAN
b) If the external test equipment determines a P2 timeout, this means that no response message has
CAN
been started and the external test equipment has verified that 29 bit CAN identifiers are not used for
legislated-OBD communication (connector F).
c) The start of a response message can either be the reception of a FirstFrame or SingleFrame which uses
one of the specified legislated-OBD 29 bit physical response CAN identifiers (see 6.3.2.3).
d) If at least one response message is started, the external test equipment shall continue to receive this
previously started response message (only applies to multiple-frame response messages) and shall
accept within P2 further response messages which use one of the specified legislated-OBD 29 bit
CAN
physical response CAN identifiers.
e) When all started response messages are completely received (positive or negative responses) and the
P2 application timer is timed out, this means that the external test equipment has verified that the
CAN
vehicle supports legislated OBD on CAN using 29 bit CAN identifiers (connector E). If all received
response messages are positive response messages, the external test equipment knows the supported
PIDs and the communication parameters of the legislated-OBD ECUs expected to respond to service 01
hex data parameter requests. Where one or more of the received response messages are negative
response messages with response code 2 hex (busyRepeatRequest), the external test equipment shall
start the initialization sequence (connector C) again after a minimum delay of 200 ms. If the negative
response(s) appear(s) on six (6) subsequent sequences, the external test equipment will assume that the
vehicle is not compliant with ISO 15765-4 (connector F). This means that the legislated OBD-related
ECU(s) shall provide a positive response within a maximum of five (5) retries.
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ISO 15765-4:2005(E)

Figure 5 — Initialization sequence — 29 bit CAN identifier response handling
5 Session layer
All legislated OBD shall take place during the default diagnostic session.
There shall always be exactly one diagnostic session active in a legislated OBD-related ECU. A legislated-
OBD-related ECU shall always start the default diagnostic session when powered up. If no other diagnostic
session is started, then the default diagnostic session shall be running as long as the legislated-OBD-related
ECU is powered.
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ISO 15765-4:2005(E)
A legislated-OBD-related ECU shall be capable of providing all diagnostic functionality defined for legislated
OBD in the default diagnostic session and under normal operating conditions.
There is no need for any diagnostic service to be sent to the legislated-OBD-related ECU to keep the default
diagnostic session active.
6 Network layer
6.1 General
The network layer of the external test equipment and the legislated-OBD-compliant vehicle ECU(s) — from
the external test equipment point of view — shall be in accordance with ISO 15765-2 and the
restrictions/additions given in 6.2 to 6.4.
6.2 Addressing formats
For legislated-OBD communication, only the normal addressing format — in the case of 11 bit CAN
identifiers — and only the n
...