ISO 17987-6:2025

International
Standard
ISO 17987-6
Second edition
Road vehicles — Local Interconnect
2025-05
Network (LIN) —
Part 6:
Protocol conformance test
specification
Véhicules routiers — Réseau Internet local (LIN) —
Partie 6: Spécification du protocole d'essai de conformité
Reference number
© ISO 2025
All rights reserved. Unless otherwise specified, or required in the context of its implementation, 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
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .vii
Introduction .viii
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, symbols and abbreviated terms . 1
3.1 Terms and definitions .1
3.2 Symbols .2
3.3 Abbreviated terms .3
4 Conventions . 4
5 General test specification considerations . 5
5.1 General .5
5.2 Test conditions .5
5.3 Mandatory requirements for IUT as commander .5
5.4 Mandatory requirements for IUT as responder .5
5.5 Test case architecture .5
5.6 Classification .6
5.7 Test system requirements .6
5.7.1 Generation of LIN frames .6
5.7.2 Common requirements for the test cases .6
5.7.3 Common requirements for bit timing testing .6
5.7.4 Test system for IUT as responder node .7
5.7.5 Sleep state verification for IUT as responder node .7
5.8 Test system definition .8
5.9 Global predefinitions for the test setup .8
5.9.1 Configuration of IUT and test system .8
5.9.2 Default delays for frame headers .9
5.9.3 Default bit rate . .9
5.9.4 Time measurement .9
5.9.5 Default spaces between the different frame parts of a LIN message .10
6 Essential test cases before test start . 10
6.1 General .10
6.2 [PT-CT 1] Diagnostic frame “commander request”, IUT as responder .10
6.3 [PT-CT 2] Diagnostic frame “responder response”, IUT as responder .10
6.4 [PT-CT 3] Error in received frame, IUT as responder .11
7 Timing parameters .11
7.1 General .11
7.2 [PT-CT 4] Length of break field low phase, IUT as commander .11
7.3 [PT-CT 5] Variation of length of break field low phase, IUT as responder . 12
7.4 [PT-CT 6] Length of break delimiter, IUT as commander . 12
7.5 [PT-CT 7] Variation of length of break delimiter, IUT as responder . 13
7.6 [PT-CT 8] Inconsistent break field error, IUT as responder .14
7.7 [PT-CT 9] Inconsistent sync byte field error, IUT as responder .14
7.8 [PT-CT 10] Bit rate detection, IUT as responder with making use of detection .14
7.9 [PT-CT 10] Verification of the sync byte field, IUT as commander .16
7.10 [PT-CT 11] Incomplete frame reception, IUT as responder .16
7.11 [PT-CT 12] Unknown frame reception, IUT as responder .17
7.12 [PT-CT 13] Length of header, IUT as commander .17
7.13 [PT-CT 14] Variation of length of header, IUT as responder .18
7.14 [PT-CT 15] Bit rate tolerance, IUT as commander .18
7.15 [PT-CT 16] Bit rate tolerance, IUT as responder without making use of synchronization .19
7.16 [PT-CT 17] Bit rate tolerance, IUT as responder with making use of synchronization .19
7.17 Length of response . 20

iii
7.17.1 [PT-CT 18] Length of response, IUT as responder . 20
7.17.2 [PT-CT 19] Length of response, IUT as commander .21
7.17.3 [PT-CT 20] Acceptance of response field, IUT as responder .21
7.18 Verification of schedule table timing . 22
7.18.1 [PT-CT 21] Verification of jitter, IUT as commander . 22
7.18.2 [PT-CT 22] Schedule table management, IUT as commander . 23
7.19 [PT-CT 23] Sample point test, IUT as responder .24
7.20 [PT-CT 24] Initialization time, IUT as responder. 25
8 Communication without failure .26
8.1 Variation of LIN identifier . 26
8.1.1 [PT-CT 25] Variation of LIN PID, IUT as commander . 26
8.1.2 [PT-CT 26] Variation of LIN PIDs of subscribed frames, IUT as responder . 26
8.1.3 [PT-CT 27] Variation of LIN identifier of published frames, IUT as responder .27
8.2 Transmission of the checksum byte .27
8.2.1 [PT-CT 28] Transmission of the checksum byte “classic checksum”, IUT as
responder .27
8.2.2 [PT-CT 29] Transmission of the checksum byte “enhanced checksum”, IUT as
responder . 28
8.2.3 [PT-CT 30] Transmission of the checksum byte “classic checksum”, IUT as
commander. 28
8.2.4 [PT-CT 31] Transmission of the checksum byte of unconditional frames, IUT as
commander. 28
8.3 Unused bits . 29
8.3.1 [PT-CT 32] Unused bits, IUT as commander . 29
8.3.2 [PT-CT 33] Unused bits, IUT as responder . 29
8.4 Reserved frame . 30
8.4.1 [PT-CT 34] Reserved frame, IUT as responder . 30
8.5 [PT-CT 35] Diagnostic frame commander request, IUT as commander . 30
8.6 Supported frames according to the IUT specification .31
8.6.1 [PT-CT 36] Supported Tx frames according to the IUT specification, IUT as
responder .31
8.6.2 [PT-CT 37] Supported Rx frames according to the IUT specification, IUT as
responder .31
9 Communication with failure .32
9.1 General .32
9.2 [PT-CT 38] Bit error, IUT as responder .32
9.3 [PT-CT 39] Framing error in header of published frame, IUT as responder . 33
9.4 [PT-CT 40] Framing error in response field of subscribed frame, IUT as responder . 34
9.5 [PT-CT 41] Checksum error by inversion, IUT as responder . 34
9.6 [PT-CT 42] Checksum error by carry, IUT as responder . 35
9.7 [PT-CT 43] Communication robustness, IUT as responder . 35
10 Event triggered frames .35
10.1 General . 35
10.2 [PT-CT 44] Event triggered frame, IUT as responder . 36
10.3 Event triggered frame with collision . 36
10.3.1 [PT-CT 45] Event triggered frame with collision resolving, IUT as responder . 36
10.3.2 [PT-CT 46] Event triggered frame with errors in collision resolving, IUT as
responder .37
10.3.3 [PT-CT 47] Event triggered frame with collision resolving, IUT as commander.37
10.3.4 [PT-CT 48] Error in transmitted frame with collision, IUT as responder . 38
11 Status management .38
11.1 [PT-CT 49] Error in received frame, IUT as responder . 38
11.2 [PT-CT 50] Error in transmitted frame, IUT as responder . 38
11.3 [PT-CT 51] response_error signal handling, IUT as responder . 39
12 Sleep/wake-up/power mode tests .39
12.1 [PT-CT 52] Send “go-to-sleep command”, IUT as commander . 39

iv
12.2 [PT-CT 53] Receive “go-to-sleep command”, IUT as responder . 40
12.3 [PT-CT 54] Receive a wake-up signal, IUT as commander .41
12.4 [PT-CT 55] Receive a wake-up signal, IUT as responder .41
12.5 Send a wake-up signal .42
12.5.1 [PT-CT 56] Send a wake-up signal, IUT as commander and IUT as responder .42
12.5.2 [PT-CT 57] Send a block of wake-up signals, IUT as responder .42
12.5.3 [PT-CT 58] Wait after one block of wake-up signals, IUT as responder .43
12.5.4 [PT-CT 59] Trigger wake-up signal followed by a frame header from commander,
IUT as responder .43
12.6 [PT-CT 60] ECU power loss, IUT as commander . 44
12.7 [PT-CT 61] Powered up with LIN shorted, IUT as commander . 44
12.8 [PT-CT 62] LIN shorted before scheduling, IUT as commander .45
12.9 [PT-CT 63] LIN shorted after start of scheduling, IUT as commander .45
13 Sleep state after bus idle .46
13.1 [PT-CT 64] Sleep state after event and bus idle, IUT as responder . 46
13.2 [PT-CT 65] Sleep state after bus idle with power up and wake-up signal, IUT as
responder .47
13.3 [PT-CT 66] Timeout after bus idle, IUT as responder . 48
14 Frame ID range assignment .48
14.1 [PT-CT 67] Frame ID range assignment with indirect response, IUT as responder . 48
14.2 [PT-CT 68] Frame ID range unassignment with indirect response, IUT as responder . 49
15 Wildcards . .50
15.1 [PT-CT 69] Request with direct response, IUT as responder . 50
16 ReadByIdentifier command .50
16.1 LIN product identification . 50
16.1.1 [PT-CT 70] LIN product identification request with direct response, IUT as
responder . 50
16.1.2 [PT-CT 71] LIN product identification — With interleaved unconditional frame,
IUT as responder .51
16.2 [PT-CT 72] ReadByIdentifier command with correct NAD, IUT as responder .51
16.3 [PT-CT 73] ReadByIdentifier command with incorrect addressing, IUT as responder .52
17 NAD assignment . .53
17.1 General . 53
17.2 [PT-CT 74] NAD assignment — Followed by ReadByIdentifier service, IUT as responder . 53
17.3 [PT-CT 75] NAD assignment — With positive response, IUT as responder . 53
17.4 [PT-CT 76] NAD assignment — Initial NAD, IUT as responder . 53
18 Save Configuration .54
18.1 General . 54
18.2 [PT-CT 77] Save configuration — With positive response, IUT as responder . 54
18.3 [PT-CT 78] Save configuration — Save a new NAD, IUT as responder . 54
18.4 [PT-CT 79] Save configuration — Save new frame identifiers, IUT as responder . 55
19 Transport protocol .56
19.1 [PT-CT 80] Transport layer functional request, IUT as responder . 56
19.2 [PT-CT 81] Abort diagnostic communication with new diagnostic request, IUT as
responder . 56
19.3 [PT-CT 82] IUT receives a segmented request as specified, IUT as responder . 56
19.4 [PT-CT 83] IUT receives a segmented request interleaved with unconditional frame,
IUT as responder .57
19.5 [PT-CT 84] IUT receives a segmented request with interleaved functional request, IUT
as responder . 58
19.6 IUT shall ignore request after timeout .59
19.6.1 [PT-CT 85] IUT shall ignore segmented requests on N_Cr timeout, IUT as
max
responder .59
19.6.2 [PT-CT 86] IUT shall observe transport layer N_As timeout, IUT as responder . 60
max
v
19.7 [PT-CT 87] IUT shall ignore segmented requests with wrong sequence numbering, IUT
as responder .61
19.8 [PT-CT 88] IUT shall respond with correct segmented response, IUT as responder .62
19.9 IUT sends a segmented response with interleaved unconditional frames . 63
19.9.1 [PT-CT 89] IUT sends a segmented response with interleaved unconditional
frame, IUT as responder . 63
19.9.2 [PT-CT 90] IUT sends a segmented response with interleaved functional
request, IUT as responder . 64
19.10 [PT-CT 91] IUT shall not respond to responder response header if there is no request
before, IUT as responder . 65
19.11 [PT-CT 92] IUT shall not respond to responder response header if the response is
already sent, IUT as responder . 65
19.12 [PT-CT 93] IUT shall abort segmented response on N_Cs timeout, IUT as responder . 66
max
Annex A (normative) LIN AA procedure C protocol conformance test plan .68
Annex B (normative) LIN AA procedure D protocol conformance test plan .75
Annex C (normative) LIN AA procedure E protocol conformance test plan .81
Bibliography .104

vi
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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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 second edition cancels and replaces the first edition (ISO 17987-6:2016), which has been technically
revised.
The main changes are as follows:
— master and slave terms used for the LIN node types in the ISO 17987 series are replaced within this
document with inclusive language terms commander and responder. This also applies for abbreviations
and file formats NCF and LDF;
— variables and formulae aligned with the ISO/IEC Directives, Part 2;
— adoptions based on updates in the corresponding requirement document (ISO 17987-2);
— editorial updates and several statements improved to avoid ambiguities.
A list of all parts in the ISO 17987 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.

vii
Introduction
The LIN protocol as proposed is an automotive focused low speed universal asynchronous receiver
transmitter (UART) based network. Some of the key characteristics of the LIN protocol are signal-based
communication, schedule table-based frame transfer, commander/responder communication with error
detection, node configuration and diagnostic service transportation.
The LIN protocol is for low-cost automotive control applications as, for example, door module and air
conditioning systems. It serves as a communication infrastructure for low-speed control applications in
vehicles by providing:
— signal-based communication to exchange information between applications in different nodes;
— bit rate support from 1 kbit/s to 20 kbit/s;
— deterministic schedule table-based frame communication;
— network management that wakes up and puts the LIN cluster into sleep state in a controlled manner;
— status management that provides error handling and error signalling;
— transport layer that allows large amount of data to be transported (such as diagnostic services);
— specification of how to handle diagnostic services;
— electrical physical layer specifications;
— node description language describing properties of responder nodes;
— network description file describing behaviour of communication;
— application programming interface.
The ISO 17987 series is based on the open systems interconnection (OSI) basic reference model as specified
in ISO/IEC 7498-1 which structures communication systems into seven layers.
The OSI model structures data communication into seven layers called (top down) application layer (layer 7),
presentation layer, session layer, transport layer, network layer, data link layer and physical layer (layer 1). A
subset of these layers is used in the ISO 17987 series.
The ISO 17987 series distinguishes between the services provided by a layer to the layer above it and the
protocol used by the layer to send a message between the peer entities of that layer. The reason for this
distinction is to make the services, especially the application layer services and the transport layer services,
reusable also for other types of networks than LIN. In this way, the protocol is hidden from the service user
and it is possible to change the protocol if special system requirements demand it.
The ISO 17987 series provides all documents and references required to support the implementation of the
requirements related to the following.
— ISO 17987-1: provides an overview of the ISO 17987 series and structure along with the use case
definitions and a common set of resources (definitions, references) for use by all subsequent parts.
— ISO 17987-2: specifies the requirements related to the transport protocol and the network layer
requirements to transport the PDU of a message between LIN nodes.
— ISO 17987-3: specifies the requirements for implementations of the LIN protocol on the logical level of
abstraction. Hardware related properties are hidden in the defined constraints.
— ISO 17987-4: specifies the requirements for implementations of active hardware components which are
necessary to interconnect the protocol implementation.

viii
— ISO 17987-5: specifies the LIN application programmers interface (API) and the node configuration and
identification services. The node configuration and identification services are specified in the API and
define how a responder node is configured and how a responder node uses the identification service.
— ISO 17987-6 (this document): specifies tests to check the conformance of the LIN protocol implementation
according to ISO 17987-2 and ISO 17987-3. This comprises tests for the data link layer, the network layer
and the transport layer.
— ISO 17987-7: specifies tests to check the conformance of the LIN electrical physical layer implementation
(logical level of abstraction) according to ISO 17987-4.

ix
International Standard ISO 17987-6:2025(en)
Road vehicles — Local Interconnect Network (LIN) —
Part 6:
Protocol conformance test specification
1 Scope
This document specifies the LIN protocol conformance test. This test verifies the conformance of LIN
communication controllers with respect to ISO 17987-2 and ISO 17987-3.
This document provides all necessary technical information to ensure that test results are identical even
on different test systems, provided that the particular test suite and the test system are compliant to the
content of this document.
Annex A, Annex B and Annex C specify the protocol conformance test plans for responder nodes supporting
auto addressing procedures according procedure C, procedure D or procedure E, see ISO 17987-3:2025,
Annex C.
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, Information technology — Open Systems Interconnection — Basic Reference Model: The Basic Model
ISO 17987-1, Road vehicles — Local Interconnect Network (LIN) — Part 1: General information and use case
definition
ISO 17987-2:2025, Road vehicles — Local Interconnect Network (LIN) — Part 2: Transport protocol and network
layer services
ISO 17987-3:2025, Road vehicles — Local Interconnect Network (LIN) — Part 3: Protocol specification
ISO 17987-4:2025, Road vehicles — Local Interconnect Network (LIN) — Part 4: Electrical physical layer (EPL)
specification 12 V/24 V
3 Terms, definitions, symbols and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 17987-1, ISO/IEC 7498-1 and the
following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/

3.1.1
class B device
μC-based LIN device
Note 1 to entry: These are devices where it is possible to take measurements on the Rx and Tx interface circuits
between the μC and the transceiver.
3.1.2
class C device
integrated LIN devices (ECU) with μC and transceiver
Note 1 to entry: These are devices where it is not possible to take measurements on the Rx and Tx interface circuits
between the μC and the transceiver.
3.2 Symbols
F bit rate tolerance of the commander node  %
TOL_RES_COMMANDER
(absolute value), according to ISO 17987-3
F bit rate tolerance of a responder node without making  %
TOL_RES_RESPONDER
use of synchronization (absolute value), according
to ISO 17987-3
F bit rate tolerance of a responder node making use of  %
TOL_SYNC
synchronization (relative value to commander node after syn-
chronization, valid for the complete
message), according to ISO 17987-3
F bit rate tolerance of a responder node making use of  %
TOL_UNSYNC
synchronization, according to ISO 17987-3
R Common bit sample resolution s
BIT
R High bit sample resolution s
BIT_HIGH
T measured time between end of wake-up signal  s
AWAKE
and start of break of a header
T length of a bit (time), depending on the bit rate s
BIT
T T = T (1 − F ) s
BIT_MAX_COMMANDER BIT_MAX_COMMANDER BIT TOL_RES_COMMANDER
T T = T (1 + F ) s
BIT_MIN_COMMANDER BIT_MIN_COMMANDER BIT TOL_RES_COMMANDER
T T = T s
BIT_NOM_COMMANDER BIT_NOM_COMMANDER BIT
T break delimiter, according to ISO 17987-3 (1 − 14,6) T
BRKDEL BIT
T calculated maximum of break delimiter:  14,6 T
BRKDEL_MAX BIT
T − (T + 20 T )
HEADER_MAX BRKFLD_MIN BIT
T minimum of break delimiter, according to  1 T
BRKDEL_MIN BIT
ISO 17987-3
T break field low phase, according to (13 −
BRKFLD
ISO 17987-3 26,6) T
BIT
T calculated maximum of break field low phase: 26,6 T
BRKFLD_MAX BIT
T –(T + 20 T )
HEADER_MAX BRKDEL_MIN BIT
T minimum of break field low phase, according to  13 T
BRKFLD_MIN BIT
ISO 17987-3
T length of an 8 byte frame, according to  (124 −
FRAME
ISO 17987-3 (see frame length) 173,6) T
BIT
T = T + T
FRAME HEADER RESPONSE
T maximum length of an 8 byte frame, according to  173,6 T
FRAME_MAX BIT
ISO 17987-3
T minimum length of an 8 byte frame, according to  124 T
FRAME_MIN BIT
ISO 17987-3
T measured between falling edges of the break s
FRAME_SLOT_MEASURE
field
T length that is specified in the LDF s
FRAME_SLOT_SPECIFIED
T inter-byte space between sync byte field and  0 − 13,6 T
H_INTERBYTE BIT
protected identifier
T length of the header of a message frame based  34 − 47,6 T
HEADER BIT
on T nominal
BIT
T maximum length of the header of a message  47,6 T
HEADER_MAX BIT
frame, according to ISO 17987-3
T minimum length of the header of a message  34 T
HEADER_MIN BIT
frame, according to ISO 17987-3
T jitter according LDF or NCF of the IUT s
JITTER_DEFINED
T measured jitter as described in ISO 17987-3 s
JITTER_MEASURE
(see frame slot)
T maximum response length 126 T
RESPONSE_MAX BIT
T nominal response length 90 T
RESPONSE_MIN BIT
T measured time after that a responder node enters  s
SLEEP
automatically a sleep state ISO 17987-2:2025, 5.4
3.3 Abbreviated terms
AC alternate current
API application programming interface
BFS byte field synchronization
CF transport layer consecutive frame
DC direct current
EBS earliest bit sample
EMC electromagnetic compatibility
EMI electromagnetic interference

EPL electrical physical layer
ESD electrostatic discharge
FF transport layer first frame
GND ground
IUT implementation under test
LBS latest bit sample
Max. maximum
Min. minimum
NVM non-volatile memory
no. number
OSI open systems interconnection
PID protected identifier
PDU protocol data unit
PT-CT LIN data link layer, network layer and transport layer protocol conformance
test
RSID response service identifier
Rx Rx pin of the transceiver
RXD receive data
SF transport layer single frame
SID service identifier
SR sample window repetition
TC test case
TRX transceiver
Tx Tx pin of the transceiver
TXD transmit data
Typ typical
UART universal asynchronous receiver transmitter
4 Conventions
The ISO 17987 series and ISO 14229-7 are based on the conventions specified in the OSI service conventions
(ISO/IEC 10731) as they apply for physical layer, protocol, network and transport protocol and diagnostic
services.
5 General test specification considerations
5.1 General
This test specification is not able to cover all contingencies. Due to the fact of the missing vehicle environment,
it is possible that the IUT's behaviour differs.
5.2 Test conditions
The tests shall be done at temperature in the range of 15 °C to 35 °C.
5.3 Mandatory requirements for IUT as commander
It is mandatory for the LDF to perform the L
...