Road vehicles -- Clock extension peripheral interface (CXPI)

This document specifies the transport and network layer conformance test plan, which tests the transportation of diagnostic communication, node configuration data and network layer services using the service interface parameters reported by the lower OSI layers and submitted to the higher OSI layers. The transport layer and network layer conformance test plan contain the following descriptions: — concept of operation conformance test plan; — transport layer protocol conformance test plan; — network layer services conformance test plan; and — error detection conformance test plan.

Véhicules routiers -- Interface périphérique d’extension d'horloge (CXPI)

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Publication Date
07-Oct-2020
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5060 - Close of voting Proof returned by Secretariat
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07-Sep-2020
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INTERNATIONAL ISO
STANDARD 20794-6
First edition
2020-10
Road vehicles — Clock extension
peripheral interface (CXPI) —
Part 6:
Transport and network layer
conformance test plan
Véhicules routiers — Interface périphérique d’extension d'horloge
(CXPI) —
Partie 6: Plan de test de conformité des couches transport et réseau
Reference number
ISO 20794-6:2020(E)
ISO 2020
---------------------- Page: 1 ----------------------
ISO 20794-6:2020(E)
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© ISO 2020

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ii © ISO 2020 – All rights reserved
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ISO 20794-6:2020(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 General test specification considerations .................................................................................................................................. 3

6.1 General ........................................................................................................................................................................................................... 3

6.2 Test conditions ........................................................................................................................................................................................ 4

6.3 IUT requirements.................................................................................................................................................................................. 4

6.4 CTC definition .......................................................................................................................................................................................... 4

6.5 Test system set-up ................................................................................................................................................................................ 5

6.6 Configuration of test system and IUT .................................................................................................................................. 6

6.6.1 General...................................................................................................................................................................................... 6

6.6.2 IUT-specific set-up parameters ........................................................................................................................... 8

6.6.3 User_Specific configurations.................................................................................................................................. 8

6.6.4 T_FltMng1 configurations ........................................................................................................................................ 8

6.6.5 T_FltMng2 configurations ........................................................................................................................................ 8

6.6.6 N_ErrDet1 configurations ........................................................................................................................................ 9

6.6.7 N_ErrDet2 configurations ........................................................................................................................................ 9

6.6.8 W/S configurations ........................................................................................................................................................ 9

6.7 SUT initialisation ................................................................................................................................................................................... 9

6.7.1 General...................................................................................................................................................................................... 9

6.7.2 Default initialisation ..................................................................................................................................................... 9

7 Transport layer conformance test plan ........................................................................................................................................ 9

7.1 General ........................................................................................................................................................................................................... 9

7.2 4.CTC_1.1 – Master node – T_PDU and T_PCI data handling – T_PCItype and T_PCI_DL .....10

7.3 4.CTC_1.2 – Slave node – T_PDU and T_PCI data handling – T_PCItype and T_PCI_DL ..........10

7.4 4.CTC_1.3 – Master node – T_PDU and T_PCI data handling (T_PCItype and T_PCI_

DLext)...........................................................................................................................................................................................................11

7.5 4.CTC_1.4 – Slave node – T_PDU and T_PCI data handling (T_PCItype and T_PCI_DLext) ..12

7.6 4.CTC_1.5 – Master node – T_PDU and T_PCI data handling (T_PCItype and T_PCI_

DLext with short data field) ......................................................................................................................................................13

7.7 4.CTC_1.6 – Slave node – T_PDU and T_PCI data handling (T_PCItype and T_PCI_

DLext with short data field) ......................................................................................................................................................14

7.8 4.CTC_2.1 – Master node – TL Error detection test (T_PCItype) ...............................................................16

7.9 4.CTC_2.2 – Slave node – TL Error detection test (T_PCItype) ...................................................................17

7.10 4.CTC_2.3 – TL Error detection test (T_PCItype) using error bit ..............................................................18

7.11 4.CTC_2.4 – Master node – TL Error detection test (T_PCI_DL) .................................................................19

7.12 4.CTC_2.5 – Slave node – TL Error detection test (T_PCI_DL) .....................................................................20

7.13 4.CTC_2.6 – TL Error detection test (T_PCI_DL) using error bit ................................................................21

7.14 4.CTC_2.7 – Master node – TL Error detection test (T_PCI_DLext) .........................................................22

7.15 4.CTC_2.8 – Slave node – TL Error detection test (T_PCI_DLext) .............................................................23

7.16 4.CTC_2.9 – TL Error detection test (T_PCI_DLext) using error bit ........................................................24

8 Network layer conformance test .......................................................................................................................................................24

8.1 General ........................................................................................................................................................................................................24

8.2 3.CTC_3.1 – Master node – N_PDU specification test (N_NAD) ...................................................................25

8.3 3.CTC_3.2 – Slave node – N_PDU specification test (N_NAD) .......................................................................26

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ISO 20794-6:2020(E)

8.4 3.CTC_3.3 – Reception logic test (in the case of T_PID = 1F and N_NAD = 00 ) ....................27

16 16

8.5 3.CTC_4.1 – Master node – NL error detection (N_As timeout) .................................................................28

8.6 3.CTC_4.2 – Slave node – NL error detection (N_As timeout) ......................................................................28

Bibliography .............................................................................................................................................................................................................................30

iv © ISO 2020 – All rights reserved
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ISO 20794-6:2020(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.
A list of all parts in the ISO 20794 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.
© ISO 2020 – All rights reserved v
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ISO 20794-6:2020(E)
Introduction

ISO 20794 (all parts) specifies the application (partly), application layer, transport layer, network

layer, data link layer and physical layer requirements of an in-vehicle network called “clock extension

peripheral interface (CXPI)”.

CXPI is an automotive low-speed single wire network. It is an enabler for reducing vehicle weight and

fuel consumption by reducing wire counts to simple devices like switches and sensors.

CXPI serves as and is designed for automotive control applications, for example door control group,

light switch and HVAC (Heating Ventilation and Air Condition) systems.

The CXPI services, protocols and their key characteristics are specified in different parts according to

the OSI layers.
— Application and application layer:

— application measurement and control data communication to exchange information between

applications in different nodes based on message communication;
— wake-up and sleep functionality;

— two kinds of communication methods can be selected at system design by each node:

i) the event-triggered method, which supports application measurement- and control-based

(event-driven) slave node communication; and

ii) the polling method, which supports slave node communication based on a periodic master

schedule;
— performs error detection and reports the result to the application;
— application error management.
— Transport layer and network layer:
— transforms a message into a single packet;

— adds protocol control information for diagnostic and node configuration into each packet;

— adds packet identifier for diagnostic and node configuration into each packet;
— performs error detection and reports the result to higher OSI layers.
— Data link layer and physical layer:
— provides long and short data frames;
— adds a frame identifier into the frame;
— adds frame information into the frame;
— adds a cyclic redundancy check into the frame;

— performs byte-wise arbitration and reports the arbitration result to higher OSI layers;

— performs frame type detection in reception function;
— performs error detection and reports the result to higher OSI layers;
— performs Carrier Sense Multiple Access (CSMA);
— performs Collision Resolution (CR);
vi © ISO 2020 – All rights reserved
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ISO 20794-6:2020(E)

— generates a clock, which is transmitted with each bit to synchronise the connected nodes on the

CXPI network;
— supports bit rates up to 20 kbit/s.

To achieve this, it is based on the Open Systems Interconnection (OSI) Basic Reference Model specified

[2]

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

Figure 1 illustrates an overview of communication frameworks beyond the scope of this document

including related standards:
[6]

— vehicle normal communication framework, which is composed of ISO 20794-2 and ISO 20794-5 ;

[3] [4]

— vehicle diagnostic communication framework, which is composed of ISO 14229-1 , ISO 14229-2

[5]
and ISO 14229-8 ;
[8]

— presentation layer standards, e.g. vehicle manufacturer specific or ISO 22901-1 ODX ;

— lower OSI layers framework, which is composed of ISO 20794-3, ISO 20794-4, this document and

[7]
ISO 20794-7 .
[5]

ISO 20794 (all parts) and ISO 14229-8 are based on the conventions specified in the OSI Service

[2]

Conventions (ISO/IEC 10731 ) as they apply for all layers and the diagnostic services.

Figure 1 — ISO 20794 document reference according to OSI model
© ISO 2020 – All rights reserved vii
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INTERNATIONAL STANDARD ISO 20794-6:2020(E)
Road vehicles — Clock extension peripheral interface
(CXPI) —
Part 6:
Transport and network layer conformance test plan
1 Scope

This document specifies the transport and network layer conformance test plan, which tests the

transportation of diagnostic communication, node configuration data and network layer services using

the service interface parameters reported by the lower OSI layers and submitted to the higher OSI layers.

The transport layer and network layer conformance test plan contain the following descriptions:

— concept of operation conformance test plan;
— transport layer protocol conformance test plan;
— network layer services conformance test plan; and
— error detection conformance test plan.
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 processing systems — Open systems interconnection — Basic reference model

ISO 20794-2:2020, Road vehicles — Clock extension peripheral interface (CXPI) — Part 2: Application layer

ISO 20794-3:2020, Road vehicles — Clock extension peripheral interface (CXPI) — Part 3: Transport and

network layer

ISO 20794-4:2020, Road vehicles — Clock extension peripheral interface (CXPI) — Part 4: Data link layer

and physical layer
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 20794-3, ISO/IEC 7498-1 and

the following apply.

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
lower OSI layer
OSI layer lower than transport layer and network layer
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ISO 20794-6:2020(E)
3.2
master node

node that provides the schedule master management (include ReqTypeId transmission), the primary

clock and optionally the sleep message transmission management
3.3
slave node
node other than master node (3.2) connected to the CXPI network
3.4
protocol data unit

data byte array that contains data and the other information to establish communication

3.5
protocol control information
information that contains message type and data length
3.6
protocol control information type
information that identifies the message type
3.7
REPEAT
pseudo code command for an iteration
3.8
REPEAT END
pseudo code command for ending an iteration
3.9
single message data length
information that identifies the data length
3.10
node address
address information that identifies target node
3.11
result
transmission or reception status to report to the higher OSI layers
3.12
status report message

message which enable to observe any error occurrence and internal state on the CXPI network

Note 1 to entry: This message consists with the TST_MSG_05_REQ_PID_ERRBIT and the TST_MSG_16_RESP_

ERRBIT_0–12.
4 Symbols and abbreviated terms
4.1 Symbols
--- empty cell/undefined
kbit/s kilobit per second
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ISO 20794-6:2020(E)
4.2 Abbreviated terms
ASP abstract service primitive
CRC cyclic redundancy check
CTC conformance test case
Err error
ETS enhanced testability service
IUT implementation under test
MSG message
N_NAD network layer node address
N_PDU network layer protocol data unit
NL network layer
OSI open systems interconnection
PDU protocol data unit
PID protected identifier
PCO point of control and observation
ReqId request identifier
ReqTypeId request type identifier
SUT system under test
T_PCI transport layer protocol control information
T_PCItype transport layer protocol control information type
T_PCI_DL transport layer protocol control information single message data length
T_PDU transport layer protocol data unit
TL transport layer
TST test
5 Conventions
[2] [1]

This document is based on OSI service conventions as specified in ISO/IEC 10731 and ISO/IEC 9646-1

for conformance test system setup.
6 General test specification considerations
6.1 General

This document covers the conformance test cases (CTC) to verify the requirements described in

ISO 20794-3.
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ISO 20794-6:2020(E)
6.2 Test conditions

Tests can be performed at room temperature, if the temperature is in the range of 15° C to 35° C. Also,

the tests shall be performed under room EMI (electro-magnetic interference) conditions.

6.3 IUT requirements

The occurrence of the error specified in ISO 20794-2:2020, 9.6.8 shall be notified to the application.

The IUT shall be initialised in the CTC respectively.
6.4 CTC definition

The definition of each test case specifies, whether the IUT is a master or a slave node. Each CTC is

defined in the structure as defined in Table 1.
Table 1 — CTC definition example
Item Content
CTC # – Title [OSI layer #].CTC_[number_name]
E.g. 3.CTC_4.1 – Master node – NL error detection (N_As timeout)

Purpose E.g. This CTC verifies the master node to detect the error of an N_As timeout.

E.g. This CTC verifies that timeout error detection shall be performed correctly.

Reference REQ document, REQ number – REQ name
E.g. ISO 20794-2:2020, REQ 3.13 NL – Timing definition – NL – Timing parameters;
Prerequisite The test system set-up shall be in accordance with Figure 2.
Set-up — The IUT shall be configured as a master node or a slave node.
— The IUT shall be configured to support N_ErrDet2 (see 6.6.7), TST_MSG_01_
REQ_PID, TST_MSG_10_RESP_0–12, TST_MSG_05_REQ_PID_ERRBIT and
TST_MSG_16_RESP_ERRBIT_0–12.
— The bit rate shall be set to the default value (see 6.6.2).
— The SUT shall be initialised to the default state (see 6.7).

Step 1. The IUT shall transmit the TST_MSG_01_REQ_PID and the TST_MSG_10_RESP_0–12.

2. The LT shall transmit the TST_MSG_01_REQ_PID as the higher priority than the IUT and

the TST_MSG_10_RESP_0–12 to generate arbitration lost on the IUT.
3. The LT shall transmit the TST_MSG_05_REQ_PID_ERRBIT.
Iteration Definition of repetitions of test procedure steps.
EXAMPLE
REPEAT step 1 to step 2, 1 000 times;
REPEAT END

Expected Define the expected behaviour of the IUT by checking on the CXPI network when the test step

response is executed.
EXAMPLE
After step 3: The IUT shall transmit the TST_MSG_16_RESP_ERRBIT_0–12 with
Err_NL_TIMEOUT_A = TRUE.
The LT shall receive the TST_MSG_16_RESP_ERRBIT_0–12 with
Err_NL_TIMEOUT_A = TRUE and report to the UT.
Remark E.g. "---" if no remark
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ISO 20794-6:2020(E)
6.5 Test system set-up
[1]

The test system set-up follows the ISO/IEC 9646-1 and consists of a test system and a system under

test (SUT) connected via the physical medium. The test system implements an upper tester (UT)

and a lower tester (LT). The test system uses set-up parameters (see Figure 2, key 1) for testing the

communication with the IUT.
The UT uses the test control protocol (see Figure 2, key 2) to control the LT.

The point of control and observation (PCO) functionality between the UT of the test system and the UT

App test stub in the SUT is provided by direct logical access to the abstract service primitive interface

(ASPs (ETSs), PCO, see dashed line in Figure 2, key 3) and the associated parameters of the OSI layers as

specified in the ISO 20794 series.

The UT App test stub in the SUT (see Figure 2, key 4) supports an equivalent part of the ASP (see

Figure 2, key 3) and the associated parameters to control and measure the state(s) of the IUT.

The UT App in the test system, which represents the conformance test controller, manipulates the

service primitive interface parameters in the IUT App test stub via the ASPs (ETSs) and PCO of the OSI

layers to fulfil the purpose of each CTC.

If the IUT is a master node then the LT functions as a slave node. If the IUT is a slave node then the

LT functions as a master node. The test system shall ensure the precision of the bit time and bit

synchronisation of the master node as specified in ISO 20794-4:2020, 9.3.7.
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ISO 20794-6:2020(E)
Key
1 set-up parameters (CXPI node's electronic data sheet)
2 test control protocol

3 abstract service primitives (ASPs) based on enhanced testability services (ETS) and points of control and

observation (PCO)
4 upper tester application TestStub
Figure 2 — Test system set-up
6.6 Configuration of test system and IUT
6.6.1 General

The test system requires set-up parameters (see Figure 2, key 1), which specify OSI-4 and 3-layer

properties of the IUT. The IUT-specific data sheet (see Figure 2, key 1) includes set-up parameters which

the test system requires to perform the CTCs.

Table 2 specifies the configuration of test system and the IUT in the CTCs. In each CTC description,

configuration is specified in the 'configuration' column.
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ISO 20794-6:2020(E)
Table 2 — Configuration of test system and IUT
Configuration Configuration of test system and IUT
item
User_Specific T_FltMng1 T_FltMng2 N_ErrDet1 N_ErrDet2 W/S
Wake-up/sleep not supported not supported not not not supported
supported supported supported
T_PCItype 0000 any invalid 0000 0000 0000 0000
2 2 2 2 2
T_PCI_DL/T_PCI_ any valid any valid any invalid any valid any valid any valid
DLext
N_NAD any valid any valid any valid any invalid any valid any valid
Status report not applicable not applicable not applicable not supported by not
message applicable IUT applicable

Table 3 specifies test message names which are used by the IUT and the test system in the CTCs. In each

CTC description, the message setting is specified in the 'configuration' column. If there is no reference

to Table 3, the settings are specified in the CTC.
Table 3 — Configuration of test messages used by IUT and test system
Name Definition

TST_MSG_00_REQ_PTYPE Test message 00 of a master node including a ReqTypeId value (00 )

16 16
of T_ReqId.
TST_MSG_01_REQ_PID Test message 01 of a master node or a slave node including a
T_PID/N_PID value (01 to 7F ,) of T_ReqId/N_ReqId.
16 16

TST_MSG_02_REQ_PID_SLEEP Test message 02 of a master node including a T_PID/N_PID value (1F )

16 16
of T_ReqId/N_ReqId for diagnostic and node configuration requests or
sleep message.

TST_MSG_03_REQ_PID_UNKNOWN Test message 03 of a master node or a slave node including a not de-

fined T_PID value of T_ReqId (not defined for reception/transmission by
the IUT).

TST_MSG_04_REQ_PID_INVALID Test message 04 of a master node or a slave node including a T_PID

value of T_ReqId (not defined for reception/transmission by the IUT with
an incorrect parity bit) determined by T_Length = 01 .

TST_MSG_05_REQ_PID_ERRBIT Test message 05 of a master node or a slave node including an error bit

T_PID/N_PID value (01 to 7F ,) of T_ReqId/N_ReqId.
16 16
The value of this PID can use supplier-specific ReqId(3F ).

TST_MSG_10_RESP_0–12 Test message 10 of a master node or a slave node including FI field,

DATA field and CRC field determined by 00 ≤ T_Lenght ≤ 0C .
16 16

TST_MSG_11_RESP_LONG_0–12 Test message 11 of a master node or a slave node including FI field,

DATA field and CRC field determined by 00 ≤ T_Length ≤ 0C .
16 16

TST_MSG_12_RESP_LONG_13–255 Test message 12 of a master node or a slave node including FI field,

DATA field and CRC field determined by 0D ≤ T_Length = FF .
16 16

TST_MSG_13_RESP_UNKOWN_0–12 Test message 13 of a master node or a slave node including FI field,

DATA field and CRC field (not defined for reception/transmission by the
IUT) with a correct parity bit determined by 00 ≤ T_Length ≤ 0C .
16 16

TST_MSG_14_RESP_INVALID_0–12 Test message 14 of a master node or a slave node including FI field,

DATA field and CRC field (not defined for reception/transmission by the
IUT with an incorrect parity bit) determined by 00 ≤ T_Length ≤ 0C .
16 16

TST_MSG_15_RESP_SLEEP_8 Test message 15 of a master node including FI field, fixed byte pattern

of DATA field and CRC field fixed byte pattern is (00 , FF , FF , FF ,
16 16 16 16
FF , FF , FF , FF ,) determined by T_Length/N_Length = 08 .
16 16 16 16 16
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ISO 20794-6:2020(E)
Table 3 (continued)
Name Definition

TST_MSG_16_RESP_ERRBIT_0–12 Test message 16 of a master node or a slave node including FI field,

DATA field with an error bit and CRC field determined by
00 ≤ T_Length/N_Length ≤ 0C .
16 16
6.6.2 IUT-specific set-up parameters
The set-up parameters include at least the following information:

— the request identifier uses 01 to 7F and uses 00 by the request protected type identifier field

16 1
...

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