EN 50170:1996/A3:2002

SLOVENSKI STANDARD
01-september-2002
General purpose field communication system
General purpose field communication system
Ta slovenski standard je istoveten z: EN 50170:1996/A3:2002
ICS:
35.100.01 Medsebojno povezovanje Open systems
odprtih sistemov na splošno interconnection in general
35.200 Vmesniška in povezovalna Interface and interconnection
oprema equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN 50170/A3
NORME EUROPÉENNE
EUROPÄISCHE NORM May 2002
ICS 35.100.00; 35.200
English version
General purpose field communication system
This amendment A3 modifies the European Standard EN 50170:1996; it was approved by CENELEC on
2000-08-01. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations
which stipulate the conditions for giving this amendment the status of a national standard without any
alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the Central Secretariat or to any CENELEC member.
This amendment exists in one official version (English). A version in any other language made by
translation under the responsibility of a CENELEC member into its own language and notified to the
Central Secretariat has the same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Czech Republic,
Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands,
Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.
CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: rue de Stassart 35, B - 1050 Brussels
© 2002 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 50170:1996/A3:2002 E

Page 2
Foreword
This European Standard was prepared by the Technical Committee CENELEC TC65CX, Fieldbus.
EN 50170/A3 (ControlNet) is a serial communication system for communication between devices that wish to
exchange time critical application information in a deterministic and predictable manner. These devices include
simple I/O devices, such as sensors/actuators as well as complex control devices such as robots, programmable
logic controllers, welders, process controllers, etc.
The text of the draft was submitted to the Unique Acceptance Procedure and was approved by CENELEC as
amendment A3 to EN 50170:1996 on 2000-08-01.
The following dates were fixed:
- latest date by which the EN has to be implemented
at national level by publication of an identical national
standard or by endorsement (dop) 2002-11-01
- latest date by the national standards conflicting with
the EN have to be withdrawn (dow) 2003-08-01
General information on licensing and patents
CENELEC calls attention to the fact that patent rights are linked to EN 50170 Amendment A3 (ControlNet).
CENELEC takes no position concerning the evidence, validity and scope of this patent right. The following release
of rights was made available to BSI, the originating CENELEC National Committee. In this release of rights
EN 50170/A3 is referred to as “BSI DD241”:
Release of Rights for BS1 DD241 ControlNet
By Allen-Bradley Company, LLC.
Allen-Bradley (A-B) developed the ControlNet technology and created the specification (in collaboration with
other Parties) that has been submitted to BSI. Allen-Bradley has on an open basis provided this technology and the
related specification to the market via ControlNet International and supports its acceptance by CENELEC as an
open communications Standard.
BSI has published ControlNet as BSI DD 241 and submitted it to CENELEC for consideration as a European
Standard.
There are seven (7) Allen-Bradley US Patents tied to the technology utilised in ControlNet. These Patents, which
are used to develop compliant products and Systems, are listed below (Note: A summary of each is available at
CENELEC).
1. 5,396,197 Network Node Tap
2. 5,400,331 Communication Network Interface With Screeners for Incoming Messages
3. 5,491,531Media Access Controller For A Station On a Communication Network
4. 5,471,461 Digital Communication Network With a Moderator Station Election Process
5. 5,493,571 Digital Communication Network Data Transmission Method and Apparatus
6. 5,537,549 Communication Network with Time Coordinated Station Activity
7. 5,553,095 Method and Apparatus for Exchanging Different Classes of Data During Time Intervals

Page 3
A-B is providing BSI, CENELEC and users of the Specification the rights to develop, manufacture, market and use
products that meet the specification and utilise A-B patented technology. This part of the grant of rights is
effectively a royalty-free license to developers and users of products which incorporate the communication
technology specified in BSI DD 241 to use the 7 US patents listed above in BS1 DD 241 compliant products.
Standardisation promotes interoperability, reduces costs to the end user and simplifies System and product
integration. As a result, the license granted to users of this technology requires users of the license to:
� Develop product which conforms to the specification
� Test for compliance to the specification
� Provide documentation to the user including a Statement of compliance to the specification
A-B has attempted to test the technology as completely as is practical. The specification is written based on A-B’s
own technology and experience of A-B’s own developers as well as developer’s from other companies working for
A-B. Every reasonable effort has been made to ensure that both the technology and the specification are: accurate
and complete, but in accordance with accepted practice it is not possible to provide a warranty to users of the
technology.
Realistically if errors are discovered or extensions requested, then it may he appropriate for changes to be made to
the specification. it is expected that change requests and incorporation of the technology tied to the changes could
occur in two ways.
� The first Option is that the issue would be raised in ControlNet International, the users‘ organization that
supports the marketing and continued development of this technology Special interest groups are organized to
manage the technology and would propose the modifications to CENELEC through a national standards
committee. This is similar to the process that has been followed by other networks.
� The second Option is that CENELEC/TC 65CX would establish a working group to address the need, develop
the technology and propose changes to the specification as appropriate.
A-B conducted searches of the prior art to uncover background technology both prior to applying for the patents
listed above and more recently over the last three months at the request of CENELEC TC 6SCX and based on.
those searches, the art uncovered by the US Patent Office, and A-B’s current knowledge of this field, A-B believes
the technology represented by the patents is novel. Further, A-B is not currently aware of any claims or
infringement of any valid intellectual property rights by any other companies relating to the technology described
in the Specification that could materially affect the use of the technology.
If during the application of those Standards Intellectual Property Rights may appear and will not be made available
on reasonable and non discriminatory terms and conditions to anyone wishing to obtain such a license, applying
the rules of CEN/CENELEC Memorandum 8, this fact shall be brought to the attention of CENELEC Central
Secretariat for further action.

Page 4
Contents for EN 50170/A3 Page
Part 1 General description.5
Part 2 Physical layer and media.15
Part 3 Data link layer .55
Part 4 Network and transport layer. 113
Part 5 Data management. 249
Part 6 Station management . 277
Part 7 Communication services . 309
Part 8 Communication objects. 349

Page 5
EN 50170:1996/A3-1:2002
General Purpose
Field Communication System
Part 1
General Description
of EN 50170/A3
Page 6
EN 50170:1996/A3-1:2002
Contents
1 Scope . 7
2 Normative references . 7
3 Definitions. 7
4 Abbreviations. 12
Annex A (informative) Bibliography . 14
General Description of EN 50170, Amendment A3
This description provides an overview on the models, services and characteristics of EN 50170 Amendment A3
(EN 50170/A3), also known under the name „ControlNet“.
“ControlNet” is the trade name of ControlNet International, an independent organisation of users and vendors of
ControlNet products. This information is given for the convenience of users of this pre-standard and does not
constitute an endorsement by CENELEC of the trade name mentioned. Equivalent products may be used if they
can be shown to lead to the same results.
EN 50170/A3 is a serial communication system for communication between devices that wish to exchange time
critical application information in a deterministic and predictable manner. These devices include simple I/O
devices, such as sensors/actuators as well as complex control devices such as robots, programmable logic
controllers, welders, process controllers, etc.
EN 50170/A3 relies on the destination delivery model, and uses the producer/consumer model (also known as
publisher/subscriber model). The producer/consumer model allows the exchange of time critical application
information between a sending device (i.e. the producer) and many receiving devices (i.e. the consumers) without
the need to send the data separately to each destination. This is accomplished by attaching a unique identifier to
each piece of application information that is being produced onto the network medium. Any device that requires a
specific piece of application information simply filters the data on the network medium for the appropriate
identifier. Many devices can receive the same piece of application information from a single producing device.
EN 50170/A3 (deterministic control network) provides a high degree of protocol efficiency by utilising an implied
token passing mechanism. This mechanism allows all devices equal access to the network without the network
overhead associated with passing a “token” to each device granting it permission to send data. The protocol
utilises a time based scheduling mechanism which provides network devices with deterministic and predictable
access to the medium while preventing network collisions. This scheduling mechanism allows time critical data,
which is required on a periodic, repeatable and predictable basis, to be produced on a predefined schedule without
the loss of efficiency associated with continuously requesting or “polling” for the required data.
The network protocol supports an additional mechanism which allows data that is not time critical in nature or
which is only required on an occasional basis to utilise any available network time. This unscheduled data is
transmitted after the production of the time critical data has been completed and before the beginning of the next
scheduled production of time critical data.

Page 7
EN 50170:1996/A3-1:2002
1 Scope
This part defines the requirements for the general description of a device on the network of EN 50170/A3
(deterministic control network).
Each of the other parts of EN 50170/A3 corresponds to a specific layer of the seven layer OSI model in accordance
with EN ISO/IEC 7498-1. Figure 1 shows the location of each part within the OSI model.
Control Network Layers
OSI Reference Model Layers
Communication
Application Parts 7, 8
Layer 7
Objects & Services
Data Management
Presentation Part 5
Layer 6
Null
Session
Null
Layer 5
Message Router
Transport
Layer 4
Transport
Part 4
Connection Manager
Network
Layer 3
LLC
Data Link
Layer 2
Part 3 Part 6: Station
MAC
Management
PLS
Layer 1 Physical
Part 2
PMA
Medium
Figure 1 - Relationship of parts 1 to 8 to the ISO/OSI model
2 Normative references
EN ISO/IEC 7498-1:1995 Information processing systems — Open systems interconnection — Basic reference model —
The basic model
3 Definitions
For the purposes of EN 50170/A3 the following definitions apply.
3.1 actual packet
The measure of how frequently a specific connection produces its data.
interval (API)
3.2 allocate
To take a resource from a common area and assign that resource for the exclusive
use of a specific entity.
3.3 application
Function or data structure for which data is consumed or produced.
3.4 application
Multiple object classes that manage and provide the run time exchange of
objects
messages across the network and within the network device.

Page 8
EN 50170:1996/A3-1:2002
3.5 attribute
A description of an externally visible characteristic or feature of an object. The
attributes of an object contain information about variable portions of an object.
Typically, they provide status information or govern the operation of an object.
Attributes may also affect the behaviour of an object. Attributes are divided into
class attributes and instance attributes.
3.6 behaviour
Indication of how the object responds to particular events. Its description includes
the relationship between attribute values and services.
3.7 bit
A unit of information consisting of a 1 or a 0. This is the smallest data unit that
can be transmitted.
3.8 blanking or
The length of time required after transmitting before the node is allowed to receive.
blanking time
3.9 class
A set of objects, all of which represent the same kind of system component. A
class is a generalisation of the object; a template for defining variables and
methods. All objects in a class are identical in form and behaviour, but usually
contain different data in their attributes.
3.10 class attributes
An attribute that is shared by all objects within the same class.
3.11 class code
A unique identifier assigned to each object class.
3.12 class specific
A service defined by a particular object class to perform a required function which
service
is not performed by a common service. A class specific object is unique to the
object class which defines it.
3.13 client
(1) An object which uses the services of another (server) object to perform a task.
(2) An initiator of a message to which a server reacts.
3.14 communication
Components that manage and provide run time exchange of messages across the
objects
network such as the Connection Manager object, the unconnected message
manager (UCMM), and the Message Router object.
3.15 connection
A logical binding between two application objects. These application objects may
be within the same or different devices.
3.16 connection ID
Identifier assigned to a transmission that is associated with a particular connection
(CID)
between producers and consumers that identifies a specific piece of application
information.
3.17 connection path
The attribute is made up of a byte stream which defines the application object to
which a connection instance applies.
3.18 connection point
A buffer that is part of another object. The buffer is represented as a subinstance of
an assembly object.
3.19 consume
The act of receiving data from a producer.
3.20 consumer
A node that is receiving data from a producer.
3.21 consuming
The application that consumes data.
application
3.22 CRC error
Error that occurs when the cyclic redundancy check (CRC) value does not match
the value generated by the transmitter.
3.23 cyclic
Term used to describe events which repeat in a regular and repetitive manner.
3.24 deafness
The node can not hear the moderator frame but can hear other link traffic.
3.25 device
A physical hardware connection to the link. A device may contain more than one
node.
3.26 device profile
A collection of device dependent information and functionality providing
consistency between similar devices of the same device type.

Page 9
EN 50170:1996/A3-1:2002
3.27 drop cable
A cable that connects a node to the trunk cable (this is an integral part of network
taps).
3.28 end delimiter
A unique set of MAC symbols that identifies the end of a MAC frame.
3.29 end node
A producing or consuming node.
3.30 end point
One of the communicating entities involved in a connection.
3.31 error
A discrepancy between a computed, observed or measured value or condition and
the specified or theoretically correct value or condition.
3.32 fixed tag
A two byte tag which identifies a specific service to be performed by the node
identified in the second byte of the fixed tag. The second byte of the fixed tag
contains the MAC ID of the destination node.
3.33 frame
Single data transfer on a link.
3.34 generic tag
A three byte tag which identifies a specific piece of application information (same
as connection ID).
3.35 guardband
Time slot allocated for the transmission of the moderator frame.
3.36 implicit token
The mechanism that governs the right to transmit is implied (e.g. no actual token
message is transmitted on the medium). Each node keeps track of the MAC ID of
the node that it believes currently holds the right to transmit. The right to transmit
is passed from node to node by keeping a record of the node that last transmitted.
A slot time is used to allow a missing node to be skipped in the rotation.
3.37 implicit token
Register that contains the MAC ID of the node that holds the right to transmit.
register
3.38 instance
The actual physical occurrence of an object within a class. Identifies one of many
objects within the same object class. For example: California is an instance of the
object class state. The terms object, instance, and object instance are used to refer
to a specific instance.
3.39 instance attributes
An attribute that is unique to an object instance and not shared by the object class.
3.40 instantiated
An object that has been created in a device.
3.41 keeper
Object responsible for distributing link configuration data to all nodes on the link.
3.42 library element
A derived or standard data type, function, function block, program or resource in
EN 61131 - programmable controllers.
3.43 link
Collection of nodes with unique MAC IDs. Segments connected by repeaters make
up a link; links connected by routers make up a network.
3.44 little endian
Describes a model of memory organisation which stores the least significant byte at
the lowest address. On the network medium, the lowest order byte is transferred
first.
3.45 Lpacket
The Lpacket (or link packet) is a piece of application information that contains a
size, control byte, tag, and link data. Peer Data Link Layers use Lpackets to send
and receive service data units from higher layers in the OSI stack.
3.46 MAC frame
A collection of MAC symbols transmitted on the medium that contains a preamble,
start delimiter, source MAC ID, Lpackets, CRC, and end delimiter.
3.47 MAC symbol
Symbols that represent the data bits to be encoded and transmitted by the Physical
Layer.
3.48 maximum
Node with highest MAC ID that can use scheduled time on a link.
scheduled node
3.49 maximum
Node with highest MAC ID that can use unscheduled time on a link.
unscheduled node
Page 10
EN 50170:1996/A3-1:2002
3.50 member
A piece of an attribute that is structured as an array.
3.51 message router
The object within a node that distributes messaging requests to the appropriate
application objects.
3.52 moderator
The node with the lowest MAC ID that is responsible for transmitting the
moderator frame.
3.53 moderator frame
A MAC frame transmitted by the node with the lowest MAC ID for the purpose of
synchronising the nodes and distributing the link configuration parameters.
3.54 multicast
A connection from one node to many. Multicast connections allow messages from
connection
a single producer to be received by many consumer nodes.
3.55 network
A series of nodes connected by some type of communication medium. The
connection paths between any pair of nodes can include repeaters, routers and
gateways.
3.56 network access
Physical Layer variant that allows a temporary node to be connected to the link by
port (NAP)
connection to the NAP of permanent node.
3.57 network address
A node’s address on the link (also called MAC ID).
or node address
3.58 network status
Indicators on a node indicating the status of the Physical and Data Link Layers.
indicators
3.59 network update
Repetitive time interval in which data can be sent on the link.
time (NUT)
3.60 node
A connection to a link that requires a single MAC ID.
3.61 non-concurrence
A transmission is received from an unexpected MAC ID. It appears to violate the
time based access protocol. This may occur when a connection is made between
two working links that are not synchronised with each other but who have the same
configuration information.
3.62 non-data symbol
A Physical Layer symbol which violates the requirements of Manchester Biphase L
encoding.
3.63 object
An abstract representation of a particular component within a device, i.e. :
(1) An abstract representation of a computer’s capabilities. Objects can be
composed of any or all of the following components:
a) data (information which changes with time);
b) configuration (parameters for behaviour);
c) methods (things that can be done using data and configuration).
(2) A collection of related data (in the form of variables) and methods (procedures)
for operating on that data that have clearly defined interface and behaviour.
3.64 object specific
A service defined by a particular object class to perform a required function which
service
is not performed by a common service. An object specific service is unique to the
object class which defines it.
3.65 optical isolators,
A component located within the Physical Layer transceiver of a node that converts
optos
current into light, and then back to an electrical signal.
3.66 originator
The client responsible for establishing a connection path to the target.
3.67 permanent node
A node whose connection to the network does not utilise the network access port
(NAP) Physical Layer variant. This node may optionally support a NAP Physical
Layer variant to allow temporary nodes to connect to the network.
3.68 point-to-point
A connection that exists between two nodes only. Connections can be either point-
connection
to-point or multicast.
3.69 produce
Act of sending data to be received by a consumer.

Page 11
EN 50170:1996/A3-1:2002
3.70 producer
A node that is responsible for sending data.
3.71 redundant media
A system using more than one medium to help prevent communication failures.
3.72 repeater
Two–port active Physical Layer device that reconstructs and retransmits all traffic
on one segment to another segment.
3.73 requested packet
The measure of how frequently the originating application requires the
interval (RPI)
transmission of data from the target application.
3.74 rogue
A node that has received a moderator frame that disagrees with the link
configuration currently used by this node.
3.75 scheduled
Data transfers that occur in a deterministic and repeatable manner on predefined
NUTs.
3.76 scope
The scope in the object specification contains a brief functional description of the
object class.
3.77 segment
Trunk–cable sections connected via taps with terminators at each end; a segment
has no active components and does not include repeaters.
3.78 serial number
A unique 32 bit integer assigned by each manufacturer to every device. The
number need only be unique with respect to the manufacturer.
3.79 server
An object which provides services to another (client) object.
3.80 service
Operation or function than an object and/or object class performs upon request
from another object and/or object class. A set of common services is defined and
provisions for the definition of object-specific services are provided. Object-
specific services are those which are defined by a particular object class to perform
a required function which is not performed by a common service.
3.81 slot time
The maximum time required for detecting an expected transmission. Each node
waits a slot time for each missing node during the implied token pass.
3.82 start delimiter
A unique set of MAC symbols that identifies the beginning of a MAC frame.
3.83 supernode
Node with MAC ID of zero. This node is reserved for special Data Link Layer
functions.
3.84 tag
Shorthand name for a specific piece of application information. A tag can be 2 or
3 bytes long.
3.85 tap
Point of attachment from a node’s coax Physical Layer to the coax trunk cable. A
tap provides easy removal of a node without disrupting the link.
3.86 target
The end-node to which a connection is established.
3.87 temporary node
Same as transient node.
3.88 terminator
A resistor (mounted in a BNC plug) placed on the ends of segments to prevent
reflections from occurring at the ends of cables for the coax Physical Layer.
3.89 Tminus
The number of NUTs before a new set of link configuration parameters are to be
used.
3.90 tone
The instant of time which marks the boundary between two NUTs.
3.91 tool
An executable software program which interacts with the user to perform some
function.
3.92 transaction id
Field within the UCMM header that matches a response with the associated
request. The server echoes this field in the response message.
3.93 transceiver
The physical component within a node that provides transmission and reception of
signals onto and off of the medium.

Page 12
EN 50170:1996/A3-1:2002
3.94 transient node
A node that is only intended to be connected to the network on a temporary basis
using the NAP Physical Layer medium connected to the NAP of a permanent node.
3.95 trunk–cable
Length of trunk cable between any two taps.
section
3.96 trunk cable
Bus or central part of a cable system.
3.97 unconnected
The component within a node that transmits and receives unconnected explicit
message manager
messages and sends them directly to the Message Router object.
(UCMM)
3.98 unconnected
The messaging service which does not rely on the set up of a connection between
service
devices before allowing information exchanges.
3.99 unscheduled
Data transfers that use the remaining time in the NUT after the scheduled transfers
have been completed.
4 Abbreviations
For the purposes of EN 50170/A3 the following abbreviations apply.
4.1 ACM
access control machine
4.2 API
actual packet interval
4.3 ASCII
American Standard Code for Information Interchange (EN ISO/IEC 646)
4.4 BNC
A connector for coaxial cable having a bayonet-type shell with two small knobs on
the female connector, which lock into spiral slots in the male connector when it is
twisted. (see EN 122120:1993 or A.1 for reference material)
4.5 CA
clock accuracy
4.6 CID
connection ID
4.7 CIP
The control and information protocol defined by Part 4 of EN 50170/A3. CIP
includes both connected and unconnected messaging.
4.8 Coax
coaxial cable
4.9 CRC
cyclic redundancy check
4.10 DLL
Data Link Layer
4.11 LED
light emitting diode.
4.12 LLC
logical link control sublayer
4.13 MAC
media access control sublayer
4.14 MAC ID
the address of a node
4.15 NAP
network access port
4.16 ND
non-data symbol
4.17 NUT
network update time
4.18 PDU
protocol data unit
4.19 OSI
open systems interconnection (see EN ISO/IEC 7498)
4.20 PLS
Physical Layer signalling sublayer
4.21 PMA
Physical Layer medium attachment sublayer
4.22 PT
programming terminal (a temporary network connection)

Page 13
EN 50170:1996/A3-1:2002
4.23 Rcv
receive
4.24 RM
repeater machine
4.25 RPI
requested packet interval
4.26 Rx
receive
4.27 RxLLC
receive logical link control
4.28 RxM
receive machine
4.29 SDU
service data unit
4.30 SEM
state event matrix
4.31 SMAX
MAC ID of the maximum scheduled node
4.32 STD
state transition diagram, used to describe object behaviour
4.33 Tx
transmit
4.34 TxLLC
transmit logical link control
4.35 TxM
transmit machine
4.36 UMAX
MAC ID of maximum unscheduled node
4.37 Xmit
transmit
Page 14
EN 50170:1996/A3-1:2002
Annex A
(informative)
Bibliography
A.1 Standards publications
Normative:
EN 61131-3:1993, Programmable controllers —Part 3: Programming languages
EN 122120:1993, Harmonized system of quality assessment for electronic components. Sectional Specification: Radio
Frequency Coaxial Connectors. Series BNC
ISO/IEC 646:1991, Information technology — ISO 7-bit coded character set for information interchange
Informative:
ISO/IEC 3309:1993, Information technology — Telecommunications and information exchange between systems — High-level
data link control (HDLC) procedures — Frame structure
ISO/IEC 7498-3:1997, Information processing systems — Open systems interconnection — Basic reference model — Naming
and addressing
ISO/IEC 8824:1990, Information technology — Open systems interconnection— Specification of abstract syntax notation one
(ASN.1)
ISO/IEC 8825:1990 , Information technology — Open systems interconnection — Specification of basic encoding rules for
abstract syntax notation one (ASN.1)
ISO/IEC 8886:1992, Information technology— Telecommunications and information exchange between systems — Data link
service definition for open systems interconnection
ISO/IEC 10039:1991, Information technology — Open systems interconnection — Local area networks — Medium Access
Control (MAC) service definition
ISO/IEC 10646-1:1993, Information technology -- Universal Multiple-Octet Coded Character Set (UCS) --
Part 1: Architecture and Basic Multilingual Plane
ISO/IEC 10731:1994, Information technology — Open systems interconnection — Basic reference model — Conventions for
the definition of OSI services
ANSI X3.66:1979 (R1990), Advanced data communication control procedures (ADCCP)
ANSI X3.159-1989, Information Systems — Programming Language C
ANSI X3J16 / ISO WG21 committee draft working paper for a C++ standard
EIA RS-422-A:1978, Electrical characteristics of a balanced Voltage Digital Interface Circuits
IEEE 754:1985 (R1990), Binary floating-point arithmetic
A.2 Other publications
”Strategies for Real-time Systems Specification” by D. J. Hatley and I. A. Pirbhai

Page 15
EN 50170:1996/A3-2:2002
General Purpose
Field Communication System
Part 2
Physical Layer and Media
for EN 50170/A3
Page 16
EN 50170:1996/A3-2:2002
Contents
1 Scope . 18
2 Normative references. 18
3 Definitions and abbreviations. 18
4 PLS sublayer. 19
5 PMA sublayer. 22
6 Media . 22
7 Coaxial medium and its Physical Layer variant . 23
8 Fibre medium and its Physical Layer variant. 40
9 NAP medium and its Physical Layer variant. 43
10 RM sublayer and redundant Physical Layers. 49
Annex A (informative) Bibliography . 54

Page 17
EN 50170:1996/A3-2:2002
Introduction
The Physical Layer and Media part specifies normative requirements and provides informative reference design
examples for both coaxial copper and fibre media.
Clauses 5, 6, 7, and 8 represent various Physical Layer variants. Coaxial copper cable medium is used for the
primary variant. Optical fibre based variants are also specified. The Physical Layer supports the inclusion of an
access port connector which allows for a simple and convenient connection to the network. This is referred to as the
Network Access Port (NAP) and provides a convenient point-to-point temporary attachment mechanism which can
be used for programming, configuration, diagnostics or other purposes.
The Physical Layer Signalling (PLS) sublayer performs those functions related to bit representation and timing and
allows information to be exchanged with the MAC sublayer and the Physical Medium Attachment (PMA) sublayer.
The PMA sublayer comprises the circuitry necessary for transmission and reception of signals on the bus. The
medium consists of those components, outside the device’s electronic components, that convey signals from one
node to another.
Signals and specifications are defined for three interfaces including the PLS to MAC interface, PLS to PMA
interface, and the PMA to medium interface. A node may include any (or more than one) Physical Layer variant but
the appropriate PMA to medium interface is provided for each Physical Layer variant implemented. This interface
specifies the electrical and mechanical requirements between each medium and the PMA. This interface is exposed
and accessible in any embodiment of the Physical Layer in a node.

Page 18
EN 50170:1996/A3-2:2002
1 Scope
This part defines the requirements for the Physical Layer of a node and the transmission of EN 50170/A3.
The Physical Layer and Media of the EN 50170/A3 corresponds to the definition of Layer 1 of the seven layer OSI
model in accordance with EN ISO/IEC 7498-1. Figure 1 shows the location of the Physical Layer and Media within
the OSI model. This figure applies to all Physical Layer variants.
Control Network Layers
OSI Reference Model Layers
Communication
Application Parts 7, 8
Layer 7
Objects & Services
Data Management
Presentation Part 5
Layer 6
Null
Session
Null
Layer 5
Message Router
Transport
Layer 4
Transport
Part 4
Connection Manager
Network
Layer 3
LLC
Data Link
Layer 2
Part 3 Part 6: Station
MAC
Management
PLS
Layer 1 Physical
Part 2
PMA
Medium
Figure 1 - Relationship to the ISO/OSI model
2 Normative references
EN ISO/IEC 7498-1:1995 Information processing systems — Open systems interconnection — Basic reference model
3 Definitions and abbreviations
For the purposes of EN 50170/A3-2 the definitions and abbreviations of EN 50170/A3-1 apply.

Page 19
EN 50170:1996/A3-2:2002
4 PLS sublayer
4.1 Clock accuracy
The timing specifications for Physical Layer Signalling shall be as defined in Table 1.
Table 1 - PLS timing characteristics
Specification Limits / Characteristics Comments
Data Rate 5 Mbit/s � CA also called MAC_Symbol rate, data “zero” or “one”
Bit Time also called MAC_Symbol time, data “zero” or “one”
200 ns � CA
Physical Layer symbol time also called Phy_Symbol time, see data encoding rules
100 ns � CA
Clock Accuracy (CA) including temperature, long term, and short term stability
� 150 ppm max.
4.2 Data recovery
The signals at the PLS to MAC interface shall be synchronised to the local Data Rate as shown in Table 1. Each
Physical Layer (PLS Layer) implementation shall provide a data recovery mechanism that recovers or reconstructs
the data received from the appropriate medium to meet the timing requirements shown in Table 1. When data
synchronisation has been attained by the PLS, the pls_lock_indication shall be true.
A portion of the received data frame may be lost or discarded in the process of attaining data synchronisation. The
specification for data timing shown in Table 1 shall be achieved prior to the beginning of the start delimiter (see
Data Link Layer, EN 50170/A3-3, clause 4, for definition of start delimiter).
4.3 Data encoding rules
The MAC_Symbols present at the MAC to PLS interface shall be encoded into the appropriate Phy_Symbols as
shown in Table 2 and Figure 2. The MAC_0 and MAC_1 shall be encoded into Phy_Symbols that represent
Manchester Biphase L data encoding rules as shown in Table 2. The MAC_ND symbols shall be used to represent
violations of the Manchester encoding rules to allow for the creation of unique data patterns used for start and end
delimiters. The signal voltage waveform (from the coax PMA sublayer) is shown in an idealized form in Figure 2 to
provide an example of the data encoding rules shown in Table 2.
Table 2 - Data encoding rules
data bits (common name) MAC_Symbol representation Phy_Symbol encoding Manchester encoded
data “zero” MAC_0 or {0} Phy_L, Phy_H or {L,H} 0
data “one” MAC_1 or {1} Phy_H, Phy_L or {H,L} 1
“non_data+” MAC_ND+ or {+} Phy_H, Phy_H or {H,H} code violation
“non_data–” MAC_ND– or {–} Phy_L, Phy_L or {L,L} code violation

Page 20
EN 50170:1996/A3-2:2002
+V
Transmitter
Off
-V
One
bit
time
(200 ns)
_
MAC_Symbols
11 0 0 +
Manchester
biphase L Time
encoding
Phy_H  Phy_L  Phy_H   Phy_L  Phy_L  Phy_H  Phy_L   Phy_H  Phy_L   Phy_L  Phy_H  Phy_H
Phy_Symbols
Figure 2 - Bit rate for Manchester encoding
4.4 MAC to PLS interface
4.4.1 General
The MAC to PLS interface need not be exposed in the implementation of any Physical Layer variant. This interface
may be internal to the node and possibly internal to a semiconductor device. If, however, conformance to the MAC
to PLS interface is claimed, it shall conform to the requirements of subclause 4.4.
4.4.2 pls_lock_indication
pls_lock_indication shall provide an indication of either data lock or Phy_Symbol synchronisation by the
PLS sublayer. Valid states for pls_lock_indication shall be true and false. pls_lock_indication
shall be true whenever valid Phy_Symbols are present at the PMA to PLS interface and the PLS to MAC interface
timing of MAC_Symbols shall conform to the requirements in Table 1 (see Data Recovery). It shall be false
between frames (when no Phy_Symbols are present on the medium) or whenever data synchronisation is lost or the
timing fails to conform to the requirements in Table 1. pls_lock_indication shall be true prior to the
beginning of the start delimiter.
4.4.3 pls_frame_indication
pls_frame_indication shall provide an indication of a valid data frame from the PMA sublayer. Valid
states for pls_frame_indication shall be true and false. pls_frame_indication shall be true upon
pls_lock_indication = true and reception of the first valid start delimiter. pls_frame_indication
shall be false at reception of next MAC_ND symbol (following the start delimiter) or pls_lock_indication =
false.
NOTE This signal provides byte synchronisation to the Data Link Layer.

Page 21
EN 50170:1996/A3-2:2002
4.4.4 pls_carrier_indication
pls_carrier_indication shall represent the presence of a signal carrier on the medium. The
pls_carrier_indication shall be true if RxCarrier (RxCarrier = true) at the PLS to PMA interface
has been true during any of the last 4 MAC symbol times and it shall be false otherwise (see associated PMA
sublayer for definition of RxCarrier).
4.4.5 pls_data_indication
pls_data_indication shall represent the MAC_Symbols that are decoded from the PMA sublayer
Phy_Symbols as shown in Table 2. Valid symbols shall be MAC_0, MAC_1, MAC_ND+ or MAC_ND– (or
MAC_Symbols). The pls_data_indication shall represent the MAC_Symbols as decoded from the PMA
sublayer whenever pls_lock_indication is true.
4.4.6 pls_status_indication
pls_status_indication shall represent the status of the frame which was received from the PMA sublayer
as shown in Table 3. Valid symbols shall be Normal, Abort, and Invalid. pls_status_indication shall
indicate Normal after reception of a frame (pls_frame_indication = true) composed of a start delimiter,
valid Manchester encoded data (no MAC_ND symbols) and an end delimiter. pls_status_indication shall
indicate Abort after reception of a frame (pls_frame_indication = true) composed of a start delimiter, valid
Manchester encoded data, and a second start delimiter. pls_status_indication shall indicate Invalid after
reception of a frame (pls_frame_indication = true) composed of a start delimiter and the detection of any
MAC_ND symbol which was not part of a start or end delimiter.
Table 3 - pls_status_indication truth table
pls_status_indication pls_frame_indication
start delimiters in a end delimiter any non-delimiter
single frame detection Manchester violations
Normal true 1 true false
Abort true 2 don’t care false
Invalid true 1 don’t care true
4.4.7 pls_data_request
pls_data_request shall represent the MAC_Symbols to be transmitted. Valid symbols shall be MAC_0, MAC_1,
MAC_ND+ or MAC_ND– as shown in Table 2. pls_data_request shall indicate MAC_0 when no data is to
be transmitted (and pls_frame_request = false).
4.4.8 pls_frame_request
pls_frame_request shall be true when pls_data_request represents MAC_Symbols to be encoded to the
appropriate Phy_Symbols and transferred to the PMA sublayer, and shall be false when no valid MAC_Symbols are
to be transferred to the PMA sublayer.
4.4.9 jabber_indication
jabber_indication shall be true if the PLS to PMA interface detects a single frame
(pls_fra
...