IEC 61162-400:2001

INTERNATIONAL IEC
STANDARD
61162-400
First edition
2001-11
Maritime navigation and radiocommunication
equipment and systems –
Digital interfaces –
Part 400:
Multiple talkers and multiple listeners –
Ship systems interconnection –
Introduction and general principles
Reference number
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INTERNATIONAL IEC
STANDARD
61162-400
First edition
2001-11
Maritime navigation and radiocommunication
equipment and systems –
Digital interfaces –
Part 400:
Multiple talkers and multiple listeners –
Ship systems interconnection –
Introduction and general principles
 IEC 2001  Copyright - all rights reserved
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– 2 – 61162-400  IEC:2001(E)
CONTENTS
FOREWORD .4
INTRODUCTION.5
1 Scope.6
1.1 General .6
1.2 Application area .6
1.3 Safety implications of using this protocol .6
1.4 Components of this standard .7
2 Normative references .8
3 Definitions .8
4 Overview and general principles.12
4.1 Introduction .12
4.2 Basic protocol functionality.12
4.3 Program modules .13
4.3.1 Physical modules.13
4.3.2 Protocol types .14
4.3.3 Protocol conformance classes .14
4.4 API versus protocol .15
4.5 Protocol level entities .15
4.6 Dependencies of actual API implementations .16
4.7 Companion standard entities .16
4.8 Relationship between specification components and products .18
5 A-profile functionality.18
5.1 Introduction .18
5.2 General principles .18
5.2.1 Separation between applications .18
5.2.2 Automatic configuration .19
5.2.3 Client-server architecture by the use of data objects.19
5.2.4 Connection oriented .19
5.2.5 Transaction oriented.19
5.2.6 Reliable transfers .19
5.2.7 Real-time properties .20
5.3 Application management .20
5.3.1 MAU states.20
5.3.2 System management .20
5.3.3 Time distribution.20
5.3.4 Load limitation .20
5.4 Data object connection management .21
5.4.1 Data object states.21
5.4.2 Server object definition.21
5.4.3 Client object connection request.21
5.4.4 Client MAU authentication .21
5.5 Message transfer.22
5.5.1 Transaction states .22
5.5.2 Basic transaction principles .22
5.5.3 Transfer mechanisms .22
5.5.4 Data marshalling .23
5.5.5 Authentication .23

61162-400  IEC:2001(E) – 3 –
5.6 Bulk transfer.23
5.6.1 Mechanism .23
5.6.2 Application level activation .24
6 T-profile functionality.24
6.1 Introduction .24
6.2 General overview of quality of service .24
6.3 The T-profile services.25
6.3.1 Network address look-up and mapping services .25
6.3.2 Reliable message service .25
6.3.3 Reliable stream service .25
6.3.4 Unreliable datagram service .25
6.3.5 System management .25
6.3.6 Time distribution.25
6.3.7 Exception handling and reporting.25
7 Companion standards.26
7.1 Introduction .26
7.2 The companion standard functionality.26
7.3 The companion standard language.26
7.4 Companion standard PFS components.27
7.5 Companion standard PFS structure .27
7.6 Companion standard application description.27
8 System configuration services .27
8.1 General .27
8.2 System configuration principles .27
8.3 Physical network configuration .28
8.4 Application configuration .28
8.5 Error monitoring and reporting.28
8.6 Load/performance monitoring and reporting .28
8.7 System inspection and configuration management .29
Annex A (normative) Typographical conventions and nomenclature .30
A.1 Use of typeface .30
A.2 Regular pattern .30
A.3 Constant representation .31
A.4 State machine descriptions.32
A.5 Context diagrams .32
A.6 Entity-relationship (ER) diagrams .33
A.7 Structure of service descriptions.33
Annex B (informative) Definition and description of the IEC 61162 series of standards .36
B.1 General .36
B.2 Rationale for specific marine standards .36
B.3 IEC 61162-1 summary.37
B.4 IEC 61162-2 summary.38
B.5 IEC 61162-3 summary.38
B.6 IEC 61162-4 series summary.38
B.7 Applicability of the different standards .39

– 4 – 61162-400  IEC:2001(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MARITIME NAVIGATION AND RADIOCOMMUNICATION
EQUIPMENT AND SYSTEMS –
DIGITAL INTERFACES –
Part 400: Multiple talkers and multiple listeners –
Ship systems interconnection – Introduction and general principles
FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of the IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, the IEC publishes International Standards. Their preparation is
entrusted to technical committees; any IEC National Committee interested in the subject dealt with may
participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. The IEC collaborates closely with the International
Organization for Standardization (ISO) in accordance with conditions determined by agreement between the
two organizations.
2) The formal decisions or agreements of the IEC on technical matters express, as nearly as possible, an
international consensus of opinion on the relevant subjects since each technical committee has representation
from all interested National Committees.
3) The documents produced have the form of recommendations for international use and are published in the form
of standards, technical specifications, technical reports or guides and they are accepted by the National
Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject
of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61162-400 has been prepared by IEC technical committee 80:
Maritime navigation and radiocommunication equipment and systems.
The text of this standard is based on the following documents:
FDIS Report on voting
80/309/FDIS 80/324/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.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 3.
The special typographical conventions and nomenclature used in this standard are defined in
annex A, which forms an integral part of this standard. Annex B is for information only.
The committee has decided that the contents of this publication will remain unchanged until
June 2005. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
61162-400  IEC:2001(E) – 5 –
INTRODUCTION
International Standard IEC 61162 is a four-part standard which specifies four digital interfaces
for applications in marine navigation, radiocommunication and system integration.
The four parts are :
IEC 61162-1 Single talker and multiple listeners
IEC 61162-2 Single talker and multiple listeners, high speed transmission
IEC 61162-3 Multiple talkers and multiple listeners – Serial data instrument network
IEC 61162-4 Multiple talkers and multiple listeners – Ship systems interconnection
Part 4 of the standard is sub-divided into a number of individual standards with part numbers
in the 400 series. This part of the standard, 400: Introduction and general principles, is the
first part.
Relationship with the other parts of the IEC 61162 series of standards in defined in Annex B
of the present standard.
– 6 – 61162-400  IEC:2001(E)
MARITIME NAVIGATION AND RADIOCOMMUNICATION
EQUIPMENT AND SYSTEMS –
DIGITAL INTERFACES –
Part 400: Multiple talkers and multiple listeners –
Ship systems interconnection – Introduction and general principles
1 Scope
1.1 General
This standard series, IEC 61162-400 and upwards, specifies a communication protocol for
use in interconnected maritime systems. It also specifies an interface description language for
use together with the protocol, a set of rules for the use of this language and a set of standard
interfaces described in the language. Finally, it also provides a test plan and list of required
documents for equipment using this standard.
This part of IEC 61162 gives a general overview of the functionality of the protocol and
provides definitions common to the other fragments of the standard.
1.2 Application area
This protocol is intended for use on the system level of an interconnected maritime navigation
and radiocommunication system. It is designed to integrate various relatively large functional
components, for example RADAR, ECDIS or conning display. As such, it complements other
protocols on the instrument level (IEC 61162-1, IEC 61162-2 and IEC 61162-3 as referred to
in annex B) and on the administrative level (mainly proprietary or de facto standard
protocols).
Although this standard covers navigation and radiocommunication equipment on the system
level, it is not limited to that. It could also find application on lower levels (process level) and
in other application areas (general automation).
1.3 Safety implications of using this protocol
This standard does not define any safety related attributes that can be applied in the
verification of the safety properties of a system using this protocol. The system safety
properties will dependent on many factors, such as
a) the protocol specification (this standard);
b) the T-profile in use (may be specified by this standard);
c) the protocol implementation (dependent on manufacturer);
d) how the protocol is used by individual components (dependent on manufacturer);
e) how the system uses the protocol (dependent on manufacturers and system integrators);
f) maintenance and supervision of the system.
These items are only examples and do not constitute a complete list. The relevant authorities
and the class societies will prescribe more detailed rules for the use of this protocol in
integrated control systems.
61162-400  IEC:2001(E) – 7 –
1.4 Components of this standard
This standard consists of a number of documents (parts). This introduction contains a general
description of the functionality of the standard and guidelines for the use of the other
documents. The relationship between documents is indicated in the figure below.
Although this set of standard documents is collectively referred to as IEC 61162-4, the actual
part numbers are in the 400-series. The part numbers are shown in the figure below.
General principles A-profile specification
API specification
(400) (401)
Basic T-profile Additional
specification (410)
T-profiles (41×)
Basic companion Additional comp.
standard (420)
standards (42×)
Test and doc.
User manuals
requirements (402)
IEC  2350/01
Figure 1 – Relationship between standard documents
The documents marked with a diagonal line pattern are not part of the standard. They are
required programmer or operator manuals provided by manufacturers of equipment or
components using this standard.
The non-shaded documents give documentation required for designers of communication
libraries implementing this standard. They are not required for manufacturers of equipment
using existing communication libraries.
The companion standards documents (shaded) are required reading for designers and
integrators of equipment using this standard. They are also of interest to those who specify
equipment for ships.
The general principles are required reading for all users of the standard. The general
principles give a high level of explanations to the various parts as shown in the table below.
Table 1 – Parts of general principles document
Clause Contents Required for part
Scope Purpose and overview All
Overview and general principles General description of All
application area and usage
A-profile functionality General description of IEC 61162-420 Companion
functionality of application level standard general principles,
protocol IEC 61162-401 A-profile
T-profile functionality General description of IEC 61162-401 A-profile
requirements for implementation IEC 61162-410 T-profile
of this protocol on top of specific
transport service
Companion standard General description of purpose Companion standards,
functionality and functionality of companion application descriptions
standards
System configuration services Requirements for integrating IEC 61162-401 A-profile
systems using this protocol IEC 61162-410 T-profile

– 8 – 61162-400  IEC:2001(E)
2 Normative references
The following normative documents contain provisions which, through reference in this text,
constitute provisions of this part of IEC 61162. For dated references, subsequent amend-
ments to, or revisions of, any of these publications do not apply. However, parties to
agreements based on this part of IEC 61162 are encouraged to investigate the possibility of
applying the most recent editions of the normative documents indicated below. For undated
references, the latest edition of the normative document referred to applies. Members of IEC
and ISO maintain registers of currently valid International Standards.
IEC 61162-1:2000, Maritime navigation and radiocommunication equipment and systems –
Digital interfaces – Part 1: Single talker and multiple listeners
IEC 61162-2:1998, Maritime navigation and radiocommunication equipment and systems –
Digital interfaces – Part 2: Single talker and multiple listeners, high speed transmission
IEC 61162-3, Maritime navigation and radiocommunication equipment and systems – Digital
interfaces – Part 3: Multiple talkers and multiple listeners – Serial data instrument network
IEC 61162-401, Maritime navigation and radiocommunication equipment and systems –
Digital interfaces – Part 401: Multiple talkers and multiple listeners – Ship systems
interconnection – Application profile
IEC 61162-410, Maritime navigation and radiocommunication equipment and systems –
Digital interfaces – Part 410: Multiple talkers and multiple listeners – Ship systems
interconnection – Transport profile requirements and basic transport profile
IEC 61162-420, Maritime navigation and radiocommunication equipment and systems –
Digital interfaces – Part 420: Multiple talkers and multiple listeners – Ship systems
interconnection – Companion standard requirements and basic companion standards
ISO/IEC 7498, Information processing systems – Open Systems interconnection – Basic
Reference Model
ISO/IEC 8859-1:1998, Information technology – 8-bit single-byte coded graphic character sets
– Part 1: Latin alphabet No. 1
3 Definitions
For the purpose of this part of IEC 61162 the following definitions apply:
3.1
A-profile
communication protocol supplying application services (see OSI 5 to 7)
3.2
ABC – anonymous broadcast (MAU)
a mechanism by which a MAU can send or receive data with no defined peer or group of
peers
———————
To be published.
61162-400  IEC:2001(E) – 9 –
3.3
accept
this term (or server, see below) is used to define the MAU (or other entity associated with it)
that has exported a data object
The term client (or connect), see below, is used about the MAU (or other entity associated
with it) that use the data object.
3.4
API – application programmer’s interface
one implementation of the required application services as defined in IEC 61162-401
NOTE One API from one manufacturer may be different from another API, although the basic functionality is the
same.
3.5
bridge (in the context of a data network)
a network bridge is used to connect two or more network segments together. It will normally
do this on the data-link level, i.e. it will be able to isolate traffic internal to one segment from
other segments, but it will not be able to perform more advanced filtering required for, for
example fire-walls
3.6
callback
a subroutine in the application program called from a service provider library as a result of a
previous service request
3.7
character
an octet containing a code from the set defined in ISO/IEC 8859-1. The null character (octet
containing all zero bits) may have special meaning
3.8
client
(connect type entity) uses the services of an accept type entity
3.9
companion standard
the A-profile part of this standard defines a protocol for transport of data structures between
nodes in an integrated ship control system. It does not in itself specify how to interpret these
data structures, i.e. if it is a temperature measurement or a rudder angle. The interpretation of
the data objects are defined by additional documents called companion standards or user
layer specifications.
The companion standards-requirements part of this standard defines rules for the creation of
companion standards and how to implement them. This part also defines some general
companion standards, for example a mapping of IEC 61162-1 telegrams
3.10
connect
(client) uses the services of an accept type entity
3.11
data marshalling
this standard defines a transmission format for data records that is independent of computer
architecture, network particulars, compilers and programming languages.
Data marshalling routines convert between this transport format and internal data repre-
sentations used in different modules

– 10 – 61162-400  IEC:2001(E)
3.12
data object
this standard is based on a simplified object-oriented client-server model. The term will be
used in this standard to denote a logical entity that is characterized by the following:
– a data object has exactly one server (one logical network node – MAU). The object comes
into existence when the information about the object is exported to the network by the
server;
– a data object has zero or several clients (MAUs). Clients can connect to the object when
the object comes into existence;
– exactly one client-available operation is defined for the object;
– the defined operation can be used by the client to be informed about state changes in the
object and/or inflict state changes on the object.
It is a “virtual” object. The server does not export it to the network, it exports the identity of
the object which points back to a physical data structure in the server. All operations on the
object are performed locally by the server, the network will transfer information about these
operations
3.13
fire-wall (in the context of a data network)
a device connecting two or more network segments together while performing certain safety
related functions. These functions are, as a minimum, to limit the load from the fire-wall onto
certain of the segments and do message filtering to ensure that only a specified sub-set of
functions are made available from certain of the segments
3.14
LNA – local network administrator
the protocol processing module that interfaces the application unit (MAU) to the network.
Each MAU has one LNA
3.15
MAPI – MAU API
a generic term for an API that allows an application program (MAU) to interface to its LNA
3.16
message
a fixed format sequence of octets that are exchanged between modules in an IEC 61162-4
system. All messages will be identified with a message code. All messages, their codes and
formats are described in the A-profile part of this standard
3.17
MAU – MiTS application unit
historical name (see MiTS)
3.18
MCP – MAU connection point
a reference to one side of a connection to a data object. A server that defines a data object
requires one MCP to handle incoming transaction requests targeted at that object. Each client
using the same data object will likewise require one MCP as a reference to the object
3.19
MiTS – maritime information technology standard
predecessor to this standard. Now superseded as a specification by the IEC 61162-4 series of
standards (see also PISCES). The IEC 61162-4 series of standards are not compatible with
MiTS, but the Internet T-profile defined in IEC 61162-410 is specified so that applications and
host computers using MiTS can coexist with equipment using this international standard.

61162-400  IEC:2001(E) – 11 –
By integrating one old and one new application on the same host computer, a gateway
between the two protocols can be devised. To facilitate conversion of MiTS compliant software,
this standard's application level services represent a superset of the services supplied by
MiTS
3.20
MTU – maximum transmission unit
longest message length over a given T-profile
3.21
octet
an eight-bit data entity (or termed a byte). An octet is the smallest transmission unit that is
discussed in this standard. Any data entity transported over the network will consist of an
integral number of octets
3.22
open systems interconnection (OSI)
This standard makes references to the ISO/OSI standard reference model for open systems
interconnection [ISO/IEC 7498], but it does not adhere to that standard with regard to the
exact services provided. The ISO/OSI standard is sometimes used as a reference for the
naming of the individual layers in the protocol stack (see figure 2)
The following conventions apply:
– with respect to functionality, the protocol definitions cover the session, the presentation
and the application layers of the OSI model (the A-profile);
– the protocol requires a set of transport services. The services can possibly be supplied by
any number of different transport protocol stacks (T-profiles). The standard transport
protocols will be defined in part 410 of this standard;
– this standard does not describe the A-profile as layered. This standard merges all the
upper three layers of the ISO/OSI model into one protocol;
– this standard refers to the companion standards or user layer as a distinct protocol layer
on top of the application layer.
Companion standards
User layer
Application
A-profile
Presentation
Session
Transport
Network
T-profile
Data link
Physical
IEC  2351/01
Figure 2 – Protocol layering
3.23
PFS – PISCES foundation specifications
standard set of companion standards, used to ensure a certain degree of vendor independent
interoperability
3.24
PISCES
the name of a European Commission sponsored research and development project that
contributed to the conversion of the former MiTS specification to this international standard

– 12 – 61162-400  IEC:2001(E)
3.25
server
an accept type entity (see accept)
3.26
stream
a sequence of octets with no internal structuring except for its start and end markers and the
sequential ordering of the octets themselves, for example a general data file can be
transmitted as a stream
3.27
T-profile
protocol supplying transport services to the A-profile (see OSI, layers 1 to 4)
3.28
transaction
the exchange of information between client and server in conjunction with an operation on a
data object. Transactions follow a general pattern where the client requests an operation on
the object, the server performs it and the client is notified of the result. Transaction types are
defined where the first or the last part is missing, i.e. where the client does not initiate the
transaction or where the client does not get information on the final result
3.29
user layer
in the OSI model, it represents what is called the companion standard in this standard.
3.30
QoS – quality of service
degree to which a certain protocol (typically T-profile) supplies certain services to the higher
levels. In the context of this standard, the QoS attributes of most interest are redundancy in
transport paths, message priority and the probability that messages are delivered as specified
(e.g. without errors and loss)
4 Overview and general principles
4.1 Introduction
This clause gives an overview of the concepts and the general principles used in the
IEC 61162-4 standard. It is an introduction to the more technical components of the standard
and gives an overview of where they are defined.
4.2 Basic protocol functionality
The protocol functionality is adapted to the requirements for high level integration of ship
equipment. Clause 5 defines the application level functionality provided by this protocol.
a) Support for soft to firm real-time applications. The protocol is not appropriate for hard real-
time data transport. The protocol provides support for different priority assignments to
different data channels.
b) High inert safety. Error states in the network or in other nodes shall not propagate to the
network or other nodes.
c) Medium active safety. The degree to which one can rely on the protocol’s QoS will be
dependent on the T-profile in use.
d) Support for message based traffic (e.g. control, supervision, data acquisition) as well as
bulk transfer (e.g. RADAR or ECDIS images). Differentiated quality of service provides
some independence between the two transport modes.
e) Support for commonly used transport primitives (remote read, write, function calls,
subscriptions and broadcasts).

61162-400  IEC:2001(E) – 13 –
f) Definition of standardized data marshalling for unambiguous transfer of information
between application written in different languages, on different hardware platforms or
under different operating systems.
g) Client-server architecture where systems can be extended incrementally by adding new
clients on top of existing servers.
h) Mechanisms for definition of unambiguous description of equipment interfaces which
support automatic code generation.
i) Support for automatic and distributed configuration of network nodes. This can be used to
provide plug and play service (incremental construction of control networks) or higher
robustness networks through automatic configuration or reconfiguration.
j) Support for network management and supervision (part of the T-profile).
k) Support for application management and supervision (through the A-profile).
l) Support for maintenance of a system-wide time base (part of the T-profile).
4.3 Program modules
4.3.1 Physical modules
This standard specifies a system where most of the communication facilities are implemented
in an application independent module called an LNA. The application module (MAU)
communicates with the LNA through a simple point to point link. The different entities are
shown in the entity relationship (ER) diagram below.
Host computer
MAU LNA
User services
Communicates
IEC  2352/01
Figure 3 – Physical components
The most characteristic aspect of the modularization is that the application unit (MAU) is
separated from the network interface module (LNA). This separation means that the
application independent part of the system (LNA) has an opportunity to supervise and control
the application module with reduced danger of error propagation from network to application
and vice versa.
The separation can be through a communication link (e.g. TCP/IP), through shared memory or
through a software library interface. The quality of the separation will determine the quality of
the inert safety properties.
Each host computer (physical node on the network) can have zero or more MAUs and zero or
one LNA. The MAU uses the services of exactly one LNA to communicate with other MAUs
(through their LNAs). Each LNA can serve any number of MAUs on or off the LNA’s host
computer.
The MAU is the container for application programs. It uses the communication services
provided by the LNA to set up communication links with other MAUs. The LNA is the
application independent communication manager.
Normally, the MAUs and the LNA are separate processes with separate contexts, even when
running on one host computer. However, other configurations are possible:

– 14 – 61162-400  IEC:2001(E)
– The LNA runs on another computer than the MAU. This is supported by this standard by
using a dedicated point to point communication link between MAU and LNA. This protocol
is described in the A-profile specification.
– The MAU and LNA may be real-time tasks on an embedded processor, sharing the same
memory and resource context (normal for many real-time operating executives).
– The MAU and LNA may be merged into one process or task sharing both memory and
general execution context. This can be a useful configuration for smaller systems where
efficiency and low overhead is of importance.
The different possible configurations are organized in conformance classes as defined in
4.3.3.
4.3.2 Protocol types
The division of the module into an application part (MAU) and a network interface part (LNA)
requires the use of two communication protocols:
– The MAU-LNA protocol that is mainly used within a host computer and is normally
implemented as an inter-process communication link, for example a Windows DLL or UNIX
shared memory. It can also be implemented as procedure calls in a monolithic LNA-MAU.
This protocol is documented in the A-profile specification and in the manufacturers’
documentation. It will not be further discussed in this part 400 of the standard.
– The LNA-LNA protocol that is used on the physical network, connecting the host
computers and their LNAs together. This protocol is defined in the A-profile and the
T-profile specifications. The T-profile provides low level transport services while the
A-profile provides the application related services, based on the T-profile services.
The A-profile services are detailed in clause 5. The T-profile services are detailed in clause 6.
4.3.3 Protocol conformance classes
The communication link between MAU and LNA and the different possibilities in how to
integrate MAU and LNA give rise to four protocol conformance classes. The conformance
class specifies to what extent an application supports the services defined in IEC 61162-401
and in IEC 61162-410. Based on how the modules are placed on different host computers, the
conformance classes can be illustrated as in figure 4.
Class 1 Class 2 Class 3 Class 4
MAU A MAU B MAU D MAU E
MAU F/LNA MAU C
LNA LNA
LNA - LNA protocols
Network
MAU - LNA protocol
IEC  2353/01
Figure 4 – Conformance classes
Four class levels of conformance for an application on a host computer are defined:
Class 1
The application contains an LNA that can accept connections from other MAUs on the same
host computer (potentially delivered as a software module) and also MAUs on other host
computers (conformance class 4) via the A-profile MAU-LNA protocol. The application supports
all MAU-LNA and LNA-LNA messages defined in IEC 61162-401. It also supports MAU-LNA
messages transmitted over one of the defined T-profiles, for example IEC 61162-410.

61162-400  IEC:2001(E) – 15 –
Class 2
The application contains an LNA that can accept connections from other MAUs on the same
host computer (potentially delivered as a software module), but not from MAUs on other host
computers (conformance class 4). The application supports all MAU-LNA and LNA-LNA
messages, but it does not support MAU-LNA messages over any defined T-profile (only over a
host computer specific inter-process communication mechanism).
Class 3
The application is an integrated MAU/LNA that cannot accept connections from other MAUs
on same or other host computers. The application only supports the LNA-LNA messages
defined in IEC 61162-401.
Class 4
The application has no LNA and is dependent on connection to an application of conformance
class 1. The application only supports the MAU-LNA messages defined in IEC 61162-401 and
only when transmitted over one of the defined T-profiles, for example IEC 61162-410.
4.4 API versus protocol
IEC 61162-401 defines a set of services that shall be provided by the API. Different APIs will
provide these services in different ways, depending on, for example programming language,
operating system and programming paradigm. The actual definition of how to use these API
services shall be documented by the designer of the API library.
4.5 Protocol level entities
IEC 61162-401 specifies several entities that are used to implement the communication
services. These are identified in the diagram below.
MAU
LNA
network node name
number
MCP Data object
Transaction
name
local identity
T-state
function
structure
server
Session Interface
MAU assoc. C-state
IEC  2354/01
Figure 5 – Protocol entities
The LNAs are the physical communication nodes. They act as switches for data traffic
between the MAUs they serve and remote LNAs with their MAUs. The network level address
will be assigned to an LNA.
The MAU is served by exactly one LNA and no MAU can exist without a corresponding LNA.
Several MAUs can be served by one LNA. Each MAU has a unique name. The name is, as a
minimum, unique for the LNA, but will normally also be unique in the network. One application
(a MAU) that is moved from one LNA to another will for this protocol be treated as the same
MAU. This also means that two MAUs with the same name cannot be distinguished by the
protocol.
– 16 – 61162-400  IEC:2001(E)
Each MAU normally has a number of MCPs (MAU connection points). An MCP is a local
reference to a global data object. Each data object is defined and served by exactly one
server MAU. Any number of client MAU (also including the server MAU itself) can make use of
the data object. Thus, each data object represents one component of the server MAU
functionality, much as a named function in a program library does. A data object has a name
and it can support exactly one operation (read, write, subscribe, etc.) with one strictly defined
input and/or output data structure.
The server MAU has one MCP for each data object it has defined. This MCP is shared
between all clients that use this data object. Each client needs one MCP for each data object
it wants to use. The server MAU accepts connection and exports the data objects to the
network. The data object is an abstract entity that represents the functions that can be
invoked in the network. Conceptually, this can be looked at as if the server defines the data
objects and the clients connect to them. Once the connection is established, the server and
client can exchange m
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