IEC 61375-2-2:2012

Electronic railway equipment - Train communication network (TCN) - Part 2-2: Wire Train Bus conformance testing

IEC 61375-2-2:2012 applies to all equipment and devices implemented according to IEC 61375-2-1, i.e. it covers the procedures to be applied to such equipment and devices when the conformance should be proven. The applicability of this standard to a TCN implementation allows for individual conformance checking of the implementation itself and is a pre-requisite for further interoperability checking between different TCN implementations.

Matériel électronique ferroviaire - Réseau embarqué de train (TCN) - Partie 2-2: Bus de Train Filaire - Essais de conformité

La CEI 61375-2-2:2012 s'applique à tous les équipements et dispositifs mis en place conformément à la CEI 61375-2-1. Elle concerne les modes opératoires à appliquer aux équipements et dispositifs dont il convient de démontrer la conformité. L'applicabilité de la présente norme à la mise en oeuvre d'un TCN permet de procéder à une vérification de conformité individuelle de la mise en oeuvre elle-même et constitue une condition préalable à un contrôle approfondi de l'interopérabilité des différentes mises en oeuvre du TCN.

General Information

• Status: Published
• Publication Date: 20-Jun-2012
• ICS: 45.060.01 - Railway rolling stock in general
• Technical Committee: TC 9 - Electrical equipment and systems for railways
• Drafting Committee: WG 43 - TC 9/WG 43
• Current Stage: PPUB - Publication issued
• Start Date: 21-Jun-2012
• Completion Date: 31-May-2012

Relations

• Replaces: IEC 61375-2:2007 - Electric railway equipment - Train bus - Part 2: Train communication network conformance testing
• Effective Date: 05-Sep-2023

Overview

IEC 61375-2-2:2012 is an international standard developed by the International Electrotechnical Commission (IEC) focused on electronic railway equipment. Specifically, it addresses the Train Communication Network (TCN) and defines the conformance testing procedures for the Wire Train Bus (WTB) components and systems. This standard applies to all equipment and devices implemented according to IEC 61375-2-1, ensuring consistent and reliable testing methods to verify that these components meet required specifications.

The importance of IEC 61375-2-2 lies in its role as a prerequisite for interoperability testing, guaranteeing that various TCN implementations can work seamlessly together. By applying rigorous conformance testing, railway manufacturers and operators can ensure the functional integrity, safety, and compatibility of train communication networks.

Key Topics

• Conformance Testing Procedures
  The standard outlines comprehensive test approaches including:

  • Basic interconnection tests for cabling and connectors
  • Capability and behavior tests for WTB nodes and cables
  • Link layer interface evaluation
  • Conformance resolution and interpretation of test results

• Protocol and Interface Requirements
  Clear definitions of electrical and communication interface requirements ensure that devices correctly implement the Wire Train Bus protocols.

• Test Cases and Methodology
  IEC 61375-2-2 provides detailed test cases for various WTB components such as trunk cables, jumper cables, extension cables, and RTP (Redundancy Management Protocol). These test suites cover aspects like line resistance, signal integrity, error handling, and data consistency.

• Conformance Assessment Process
  The document specifies a structured conformance assessment process including declaration of requirements, boundary conditions, and result analysis to determine the device under test's conformity status.

• Test Laboratory and Instrumentation Guidelines
  Annexes include recommendations on test laboratory roles, required instrumentation, and dedicated test bench architectures to support rigorous conformance verification.

Applications

• Railway Communication Equipment Manufacturers
  Manufacturers use IEC 61375-2-2 to verify their products’ compliance with WTB communication requirements before market release.

• Rail Operators and Integrators
  Operators and integrators rely on compliant equipment to ensure that train communication networks operate safely and efficiently, supporting diagnostics, control, and redundancy features.

• Interoperability Testing
  Serving as a foundation for interoperability testing, this standard ensures that communication components from different suppliers can be interconnected without issues.

• Quality Assurance and Certification
  Conformance testing guided by IEC 61375-2-2 supports quality assurance programs and certification processes in the railway industry, improving system reliability.

Related Standards

• IEC 61375-2-1
  Defines the basic Train Communication Network architecture and the fundamental specifications upon which IEC 61375-2-2 testing is based.

• IEC 61375-1
  The overarching standard covering the general concepts and definitions of Train Communication Networks.

• IEC 61375 Series
  Other parts of this series address different layers and communication buses within the TCN framework, including Ethernet Train Backbone (ETB) standards.

• Railway Signal and Communication Standards
  In conjunction with IEC 61375-2-2, related international railway communication standards provide a holistic framework for train electronics and communication systems.

---

By adhering to IEC 61375-2-2:2012, industry stakeholders can ensure that wire train bus implementations meet strict technical requirements, enhancing safety, interoperability, and performance in modern electronic railway networks. This conformance standard is essential for anyone involved in designing, testing, deploying, or certifying Train Communication Network equipment.

Standards Content (Sample)

IEC 61375-2-2 ®
Edition 1.0 2012-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Electronic railway equipment – Train communication network (TCN) –
Part 2-2: Wire Train Bus conformance testing

Matériel électronique ferroviaire – Réseau embarqué de train (TCN) –
Partie 2-2: Bus de Train Filaire – Essais de conformité

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IEC 61375-2-2 ®
Edition 1.0 2012-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Electronic railway equipment – Train communication network (TCN) –

Part 2-2: Wire Train Bus conformance testing

Matériel électronique ferroviaire – Réseau embarqué de train (TCN) –

Partie 2-2: Bus de Train Filaire – Essais de conformité

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
XD
CODE PRIX
ICS 45.060 ISBN 978-2-88912-068-0

– 2 – 61375-2-2 ¤ IEC:2012
CONTENTS
FO R EW O RD . 6
INT R O D UCT IO N . 8
1 Sc op e . 10
2 Normative references . 10
3 Terms and definitions, Abbreviations, Conventions . 10
3.1 Terms and definitions . 10
3.2 Abbreviations . 11
4 Conformance test: approach, requirements and boundaries . 12
4.1 The approach . 12
4.1.1 Requirements . 12
4.1.2 Requirements declaration statements for an IUT . 14
4.2 Boundar ies . 15
4.2.1 General . 15
4.2.2 Basic interconnection tests . 16
4.2.3 Capability tests . 16
4.2.4 Behaviour tests. 17
4.2.5 Conformance resolution tests . 17
4.2.6 Interpretation of clauses/subclauses and statements . 18
4.2.7 Relation to interoperability . 20
4.2.8 Relation to performance test . 20
4.3 Conformance assessment process outline . 21
4.3.1 General . 21
4.3.2 Analysis of results, outcomes and verdicts . 21
5 Conformance test of a WTB node, WTB trunk cable, WTB jumper cables, WTB
extension cables. 22
5.1 PICS . 22
5.1.1 Instructions for filling the PICS pro-forma . 22
5.1.2 PICS tables . 24
5.1.3 Basic interconnection tests . 32
5.1.4 Capability tests . 32
5.1.5 Behaviour tests. 32
5.1.6 Link layer interface . 47
5.1.7 The test cases . 58
6 Conformance test of RTP . 68
6.1 Ports and Traffic_Store . 69
6.2 Dataset consistency . 69
6.2.1 Error handling . 69
6.2.2 Freshness supervision . 69
6.2.3 Synchronisation dataset . 69
6.2.4 Dataset polling . 70
6.2.5 Dataset, port and logical address . 70
6.2.6 Traffic_Store Identifier . 70
6.3 Port_Address . 70
6.4 Link_Process_Data_Interface primitives . 70
6.5 Messages services and protocols . 70

61375-2-2 ¤ IEC:2012 – 3 –
7 Conformance test of a WTB-equipped consist . 70
7.1 General . 70
7.2 PICS . 71
7.2.1 Instructions for filling the PICS pro-forma . 71
7.2.2 Abbreviations . 71
7.2.3 PICS tables . 71
7.3 Test suites . 74
7.3.1 Physical interface tests . 75
7.3.2 DC test: line resistance . 75
7.3.3 WTB Link_layer ca pa b i l i t i es . 78
7.3.4 Data test storage . 85
7.4 Consist network interoperability test . 85
7.5 Application profile . 85
7.6 Several nodes on the consist . 85
8 Conformance test of NM . 85
Annex A (normative) Test laboratory role and client role . 86
Annex B (informative) Test instrumentation and dedicated test bed . 93
Bibliography . 101

Figure 1 – Insertion loss measurement . 34
Figure 2 – Measurement of the input resistance . 35
Figure 3 – End setting measurement setup 1 . 35
Figure 4 – End setting measurement setup 2 . 36
Figure 5 – Switches measurement setup 1 . 37
Figure 6 – Indirect attachment switches measurements Fixture 1 . 37
Figure 7 – Direct attachment switches measurements Fixture 1 . 38
Figure 8 – Transmitter fixtures . 39
Figure 9 – Transmitter output signal . 40
Figure 10 – Intermediate transmitted noise test fixture . 40
Figure 11 – End node transmitted noise test fixture . 41
Figure 12 – Signal and idling at transmitter . 42
Figure 13 – RF resistor example . 43
Figure 14 – Short-circuit test Fixture 1 . 43
Figure 15 – Receiver signal envelope . 45
Figure 16 – Receiver edge distortion . 46
Figure 17 – Example of relay switch logic diagram for line A . 49
Figure 18 – WTB orientation . 52
Figure 19 – Line switch identification in position P01 . 53
Figure 20 – Line switch identification in position P10 . 53
Figure 21 – Line switch identification in position P32 . 54
Figure 22 – Test suite identifier TTS1 . 55
Figure 23 – Test suite identifier TTS2 . 56
Figure 24 – Test suite identifier TTS3 . 57
Figure 25 – Line resistance . 76
Figure 26 – Crosstalk . 77

– 4 – 61375-2-2 ¤ IEC:2012
Figure 27 – Propagation delay and attenuation . 78
Figure 28 – Coach tester nodes . 83
Figure B.1 – Hardware test bed architecture . 94
Figure B.2 – Coach tester architecture . 95
Figure B.3 – Configuration of the coach tester . 99
Figure B.4 – WTB line redundancy switch-over . 100

Table 1 – Document structure . 9
Table 2 – Continuance indication . 19
Table 3 – Weak statements . 20
Table 4 – Relation to interoperability . 20
Table 5 – Relation to performance test . 21
Table 6 – PICS pro-forma identification . 24
Table 7 – PICS pro-forma implementation under test . 25
Table 8 – PICS pro-forma IUT supplier and/or test laboratory client . 25
Table 9 – PICS pro-forma identification of the standards . 26
Table 10 – PICS pro-forma global statement of conformance . 26
Table 11 – PICS pro-forma level of tes t in g . 26
Table 12 – PICS pro-forma node capability . 27
Table 13 – PICS pro-forma redundancy . 27
Table 14 – PICS pro-forma redundancy configuration . 27
Table 15 – PICS pro-forma signalling . 28
Table 16 – PICS pro-forma cable . 28
Table 17 – PICS pro-forma trunk cable . 28
Table 18 – PICS pro-forma jumper cable . 29
Table 19 – PICS pro-forma extension cable . 29
Table 20 – PICS pro-forma front panel layout . 30
Table 21 – PICS pro-forma connector arrangement . 30
Table 22 – PICS pro-forma connector layout and type . 31
Table 23 – PICS pro-forma switches type . 32
Table 24 – PICS pro-forma switches . 32
Table 25 – WTB pin to pin measurement. 38
Table 26 – Fault tolerance parameters . 42
Table 27 – Frequency sinusoidal signal . 47
Table 28 – WTB devices configuration . 50
Table 29 – TNM agent services. 51
Table 30 – Mapping Server services . 51
Table 31 – Power switch identifier. 53
Table 32 – Line switch identifier . 53
Table 33 – Test suites . 54
Table 34 – Test sequence node strength . 59
Table 35 – Test sequence change of user report . 59
Table 36 – Test sequence change of node descriptor . 60

61375-2-2 ¤ IEC:2012 – 5 –
Table 37 – Test sequence change of inauguration data . 60
Table 38 – Test sequence inauguration inhibit lengthening . 61
Table 39 – Test sequence sleep state . 61
Table 40 – Test sequence fast insertion . 62
Table 41 – Test sequence late insertion . 62
Table 42 – Test sequence process data . 63
Table 43 – Test sequence individual period 3 . 63
Table 44 – Test sequence individual period 2 . 63
Table 45 – Test sequence coupling of two compositions . 64
Table 46 –Test sequence inauguration time IUT intermediate . 65
Table 47 – Test sequence inauguration time IUT end setting main direction 2 . 65
Table 48 – Test sequence inauguration time IUT end setting main direction 1 . 65
Table 49 – Test sequence failure of the master node . 66
Table 50 – Test sequence line redundancy during regular operation . 66
Table 51 – Test sequence line redundancy during inauguration . 67
Table 52 – Test sequence measurement of basic period . 67
Table 53 – WTB link layer procedures . 68
Table 54 – PICS pro-forma identification . 71
Table 55 – PICS pro-forma WTB consist under test . 72
Table 56 – PICS pro-forma identification of consist WTB node . 72
Table 57 – PICS pro-forma identification of consist trunk cable . 73
Table 58 – PICS pro-forma identification of consist jumper cable . 73
Table 59 – PICS pro-forma identification of consist extension cable . 74

– 6 – 61375-2-2 ¤ IEC:2012
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRONIC RAILWAY EQUIPMENT –
TRAIN COMMUNICATION NETWORK (TCN) –

Part 2-2: Wire Train Bus conformance testing

FOREWORD
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patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61375-2-2 has been prepared by IEC technical committee 9:
Electrical equipment and systems for railways.
This first edition cancels the clauses of IEC 61375-2, first edition, published in 2007, relevant
to the specification of WTB conformance testing and constitutes a technical revision.
It was prepared taking into account IEC 61375-2-1, first edition.
The text of this standard is based on the following documents:
FDIS Report on voting
9/1643/FDIS 9/1667/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.

61375-2-2 ¤ IEC:2012 – 7 –
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of IEC 61375 series, under the general title Electronic railway equipment –
Train communication network (TCN), can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
‡ reconfirmed,
‡ withdrawn,
‡ replaced by a revised edition, or
‡ amended.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
– 8 – 61375-2-2 ¤ IEC:2012
INTRODUCTION
TCN is an International Standard with the aim of defining interfaces so as to achieve plug-in
compatibility:
a) between equipment located in different consists, and
b) between equipment and devices located within the same consist.
One of the key success factors for the deployment of any technology is the standardisation
and ensuring interoperability among various implementations. To facilitate interoperability a
conformance test should be implemented.
In this part of IEC 61375, the TCN hierarchical structure deals with the train bus called the
Wire Train Bus (WTB).
No other busses are taken into consideration even though they are foreseen by IEC 61375.
WTB has real-time protocols, which offer two communication services:
c) process variables, a distributed, real-time database, periodically refreshed through
broadcasting;
d) messages, transmitted on demand either as:
0. unicast messages (point-to-point) or/and
1. multicast messages.
WTB has a network management, which allows debugging, commissioning and maintenance
over the network.
This standard is structured into 8 clauses and 2 annexes.
The clauses and annexes are listed and briefly described in Table 1.

61375-2-2 ¤ IEC:2012 – 9 –
Table 1 – Document structure
Clause Description
1 Scope This clause describes the scope of this standard.
2 Normative references This clause lists the normative references.
3 Terms and definitions, abbreviations, This clause introduces basic terms and abbreviations not
conventions reported in IEC 61375-2-1.
4 Conformance test: approach, This clause is an overview of the methods of TCN
requirements and boundaries implementation verification that are available to the
developer and regulatory personnel.
Supplies information concerning the ICS and IXITpPro-
forma(s).
5 Conformance test of a WTB node, Contents: All tests on WTB are classified by nodes related
WTB trunk cable, WTB jumper cables, to WTB itself and MVB only. The main contents are:
WTB extension cables
the WTB PICS and PIXIT;
the WTB test suites;
the WTB test procedures.
6 Conformance test of RTP This clause lists the tests covered in Clauses 3 and 4
fulfilling the real time protocol.
7 Conformance test of a WTB- This clause covers the Physical Layer while the Services
equipped consist given by the WTB node are covered by the previous
clauses. Application profiles are covered by other bodies,
like communication profile as described in UIC CODE 556.
8 Conformance test of NM Partially covered by Clauses 3 and 4. Remaining parts are
not covered.
Annex A – Test laboratory and client This annex is normative.
role
Annex B – Test suites standard This annex is informative.
instrumentation
– 10 – 61375-2-2 ¤ IEC:2012
ELECTRONIC RAILWAY EQUIPMENT –
TRAIN COMMUNICATION NETWORK (TCN) –

Part 2-2: Wire Train Bus conformance testing

1 Scope
This part of IEC 61375 applies to all equipment and devices implemented according to
IEC 61375-2-1, i.e. it covers the procedures to be applied to such equipment and devices
when the conformance should be proven.
The applicability of this standard to a TCN implementation allows for individual conformance
checking of the implementation itself and is a pre-requisite for further interoperability checking
between different TCN implementations.
NOTE For a definition of TCN implementation see IEC 61375-2-1,1.3.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60571: Electronic equipment used on rail vehicles
IEC 60807(all parts), Rectangular connectors for frequencies below 3 MHz
IEC 61375-2-1: Electronic railway equipment – Train Communication Network (TCN) –
Part 2-1: Wire Train Bus (WTB)
ISO/IEC 7498 (all parts): Information technology – Open Systems Interconnection – Basic
Reference Model
ISO/IEC 9646-1:1994, Information technology – Open Systems Interconnection –
Conformance testing methodology and framework – Part 1: General concepts (Also available
as ITU-T Recommendation X.290 (1995))
ISO/IEC 9646-7:1994, Information technology – Open Systems Interconnection –
Conformance testing methodology and framework – Part 7: Implementation Conformance
Statements (Also available as ITU-T Recommendation X.296 (1995))
UIC CODE 556, Information transmission in the train (train-bus)
3 Terms and definitions, abbreviations, conventions
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/IEC 9646-1 and
IEC 61375-2-1 apply.
61375-2-2 ¤ IEC:2012 – 11 –
3.2 Abbreviations
AVI Application Variables Interface, the definition of the Process Variable services
BR Bit Rate, the rate of data throughput on the medium expressed in bits per second
(bit/s) or in hertz (Hz), whichever is appropriate
BT Bit Time, the duration of the transmission of one bit, expressed in μs
CUT Consist under Test
DMM Digital Multi Meter
ITU International Telecommunication Union, the international standardisation body for
telecommunications based in Geneva
IUT Implementation Under Test
IEC International Electrotechnical Commission, Geneva
ISO International Standard Organisation, Geneva
LLC Logical Link Control, a sub-layer within the Link Layer ruling the data exchange
LME Layer Management Entity, the entity in charge of supervising a layer on behalf of
Network Management
MAU Medium Attachment Unit, the part of a Node which interfaces electrically to the
bus and which provides/accepts binary logic signals
MOT Mean of Test
MVB Multifunction Vehicle Bus, a Consist network
MS Mapping Server, defined in UIC CODE 556
OSI Open System Interconnection, a universal communication model defined in the
ISO/IEC 7498
PCTR Protocol Conformance Test Report, defined in ISO/IEC 9646
PICS Protocol Implementation Conformance Statement, defined in ISO/IEC 9646
PIXIT Protocol Implementation Extra Information for Testing
RTP Real-Time Protocols, the common communication protocols for process data and
message data
TCN Train Communication Network, a set of communicating consist and Train Busses
TDR Time Domain Reflectometry, tool for analyzing single-ended and differential
transmission lines
TNM Train Network Management
UIC International Union of Railways , the international railways operators association
WTB Wire Train Bus
– 12 – 61375-2-2 ¤ IEC:2012
4 Conformance test: approach, requirements and boundaries
4.1 Approach
This standard specifies a general methodology for testing the conformance to the TCN
protocol standard of products in which the standard is claimed to be implemented.
This standard is organised into clauses structured into different phases of the conformance
testing process, these phases being characterised by the following roles:
a) the specification of abstract test suites for particular TCN protocols according to ISO/IEC
9646-1;
b) the derivation of executable test suites and associated testing tools according to ISO/IEC
9646-7;
Annex A specifies the rules on clients and laboratory specifying:
c) the role of a client of a test laboratory, having an implementation of TCN protocols to be
tested;
d) the operation of conformance testing, culminating in the production of a conformance test
report which gives the results in terms of the test suite(s) used and the relevant
documentation produced.
In all clauses of this standard, the scope is limited in order to meet the following objectives:
e) to achieve an adequate level of confidence in the tests as a guide to conformance;
f) to achieve comparability between the results of the corresponding tests applied in different
places at different times;
g) to facilitate communication between the parties responsible for the roles described above.
Each objective involves the framework for development of TCN test suites, as listed
hereinafter:
h) how they should relate to the various types of conformance requirement;
i) the types of test to be standardised and the types not needing standardisation;
j) the criteria for selecting tests for inclusion in a conformance test suite;
k) the notation to be used for defining tests;
l) the structure of a test suite.
Certification, an administrative procedure which may follow conformance testing, is outside
the scope of this standard.
Requirements for procurement and contracts are outside the scope of this standard.
4.1.1 Requirements
4.1.1.1 General
In the context of TCN, a real system is said to exhibit conformance if it complies with the
requirements of applicable TCN standard clauses in its communication with a reference
system, i.e. the tester.
A TCN standard is a set of interrelated clauses which, together, define behaviour of TCN
systems in their communication. Conformance of an IUT will, therefore, be expressed at two
levels, conformance to each individual clause, and conformance to the set of clauses.

61375-2-2 ¤ IEC:2012 – 13 –
The following clauses define the conformance requirements and classify them according to
attributes and into feasible groups. Attributes and grouping are defined from the general point
of view with reference to a TCN specification itself and from the IUT point of view. In the
second case, the requirement shall be declared in the appropriate PICS and PIXIT.
4.1.1.2 Conformance requirements
The conformance requirements can be:
a) mandatory requirements: these are to be observed in all cases;
b) conditional requirements: these are to be observed if the conditions, set out in the clause,
apply;
c) options: these can be selected to suit the implementation, provided that any requirements
applicable to the option are observed.
TCN essential functionality are mandatory requirements; additional functionality can be either
conditional or optional requirements.
Furthermore, conformance requirements in a Part can be stated:
d) positively: they state what shall be done;
e) negatively (prohibitions): they state what shall not be done.
Finally, conformance requirements fall into two groups:
f) static conformance requirements;
g) dynamic conformance requirements;
these are discussed in 4.1.1.3 and 4.1.1.4, respectively.
4.1.1.3 Static conformance requirements
To facilitate interoperability static conformance requirements define the allowed minimum
capabilities of an implementation. These requirements may be at a broad level, such as the
grouping of functional units and options into protocol classes, or at a detailed level, such as a
range of values that have to be supported for specific parameters of timers.
Static conformance requirements and options in TCN parts can be of two varieties:
a) those which determine the capabilities to be included in the implementation of the
particular protocol;
b) those which determine multi-layer dependencies, for example those which place
constraints on the capabilities of the underlying layers of the system in which the protocol
implementation resides. These are likely to be found in upper layer parts (e.g. network
management vs real time protocols).
All capabilities not explicitly stated as static conformance requirements are to be regarded as
optional.
4.1.1.4 Dynamic conformance requirements
Dynamic conformance requirements are all those requirements (and options) which determine
what observable behaviour is permitted by the relevant TCN part in instances of
communication. They form the bulk of each TCN protocol document. They define the set of
allowable behaviours of an implementation or real system. This set defines the maximum
capability that a conforming implementation or real system can have within the terms of the
TCN protocol document.
– 14 – 61375-2-2 ¤ IEC:2012
A system exhibits dynamic conformance in an instance of communication if its behaviour is a
member of the set of all behaviours permitted by the relevant TCN protocol part in a way
which is consistent with the PICS.
4.1.1.4.1 A conforming system
A conforming system or implementation is one which is shown to satisfy both static and
dynamic conformance requirements, consistent with the capabilities stated in the PICS, for
each protocol declared in the system conformance statement.
4.1.1.4.2 Interoperability and conformance
The primary purpose of conformance testing is to increase the probability that different
implementations are able to inter-operate.
Successful interoperability of two or more real open systems is more likely to be achieved if
they all conform to the same subset of a TCN part, or to the same selection of TCN parts,
than if they do not.
To prepare two or more systems to successfully inter-operate, it is recommended that a
comparison is made of the system conformance statements and PICSs of these systems.
If there is more than one version of a relevant TCN part indicated in the PICSs, the
differences between the versions need to be identified and their implications for
consideration, including their use in combination with other parts.
While conformance is a necessary condition, it is not on its own a sufficient condition to
guarantee interoperability capability. Even if two implementations conform to the same TCN
protocol part, they may fail to interoperate because of factors outside the scope of this
standard.
Trial interoperability is recommended to detect these factors. Further information to assist
interoperability between two systems can be obtained by extending the PICS comparison to
other relevant information, including test reports and PIXIT. The comparison can focus on:
a) additional mechanisms claimed to work around known ambiguities or deficiencies not yet
corrected in the TCN standard or in peer real systems, for example solution of multi-layer
problems;
b) selection of free options which are not taken into account in the static conformance
requirements of the TCN parts;
c) the existence of timers not specified in the TCN parts and their associated values.
NOTE The comparison can be made between two individual systems, between two or more types of product, or,
for the PICS comparison only, between two or more specifications for procurement, permissions to connect, etc.
4.1.2 Requirements declaration statements for an IUT
4.1.2.1 Protocol implementation conformance statement (PICS)
To evaluate the conformance of a particular implementation, it is necessary to have a
statement of the capabilities and options which have been implemented, and any features
which have been omitted, so that the implementation can be tested for conformance against
relevant requirements, and against those requirements only. Such a statement is called a
Protocol Implementation Conformance Statement (PICS).
In a PICS
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