IEC 61158-4-8:2007

IEC 61158-4-8
Edition 1.0 2007-12
INTERNATIONAL
STANDARD
Industrial communication networks – Fieldbus specifications –
Part 4-8: Data-link layer protocol specification – Type 8 elements

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IEC 61158-4-8
Edition 1.0 2007-12
INTERNATIONAL
STANDARD
Industrial communication networks – Fieldbus specifications –
Part 4-8: Data-link layer protocol specification – Type 8 elements

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
XF
ICS 35.100.20; 25.040.40 ISBN 2-8318-9435-2

– 2 – 61158-4-8 © IEC:2007(E)
CONTENTS
FOREWORD.7
INTRODUCTION.9
1 Scope.10
1.1 General .10
1.2 Specifications.10
1.3 Procedures.10
1.4 Applicability.10
1.5 Conformance.11
2 Normative references .11
3 Terms, definitions, symbols and abbreviations.11
3.1 Reference model terms and definitions.11
3.2 Service convention terms and definitions.12
3.3 Common terms and definitions .13
3.4 Additional Type 8 definitions.14
3.5 Symbols and abbreviations.15
4 DL-protocol .18
4.1 Overview .18
4.2 DL-service Interface (DLI) .18
4.3 Peripherals data link (PDL).22
4.4 Basic Link Layer (BLL) .58
4.5 Medium Access Control (MAC).74
4.6 Peripherals network management for layer 2 (PNM2) .108
4.7 Parameters and monitoring times of the DLL .116
Annex A (informative) – Implementation possibilities of definite PNM2 functions. 122
A.1 Acquiring the current configuration .122
A.2 Comparing the acquired and stored configurations prior to a DL-subnetwork
error .126
Bibliography.132

Figure 1 – Relationships of DLSAPs, DLSAP-addresses and group DL-addresses .13
Figure 2 – Data Link Layer Entity.18
Figure 3 – Location of the DLI in the DLL.18
Figure 4 – State transition diagram of DLI.20
Figure 5 – Location of the PDL in the DLL.22
Figure 6 – PDL connection between slave and master .23
Figure 7 – Interface between PDL-user (DLI) and PDL in the layer model .24
Figure 8 – Overview of the PDL services .24
Figure 9 – PDL_Data_Ack service between master and only one slave.26
Figure 10 – Parallel processing of PDL_Data_Ack services .26
Figure 11 – PSM and GSM service for buffer access .26
Figure 12 – Buffer_Received service to indicate successful data transfer.27
Figure 13 – Data flow between PDL-user, PDL and BLL of a PDL_Data_Ack service .30
Figure 14 – Interface between PDL and PNM2 in the layer model .30
Figure 15 – Reset, Set Value and Get Value PDL services .32

61158-4-8 © IEC:2007(E) – 3 –
Figure 16 – Event PDL service.32
Figure 17 – Transmit and receive FCBs on the master and slave sides.35
Figure 18 – Data transmission master → slave with SWA Message .36
Figure 19 – Time sequence of the data transmission master → slave with SWA
Message .36
Figure 20 – Data transmission slave → master with SWA/RWA Message.37
Figure 21 – Time sequence of the data transmission slave → master with SWA/RWA
Message .37
Figure 22 – Allocation of actions of the PDL protocol machines and data cycles .38
Figure 23 – Message transmission: master → slave.39
Figure 24 – Message transmission: slave → master.39
Figure 25 – Code octet of a PDLPDU.40
Figure 26 – Structure of a message with a size of one word.41
Figure 27 – Structure of a SPA Message .41
Figure 28 – Structure of a SVA Message .42
Figure 29 – Structure of a FCB_SET Message.42
Figure 30 – Structure of a RWA Message .42
Figure 31 – Structure of a SWA Message .43
Figure 32 – Structure of a confirmation for SPA or SVA Messages.43
Figure 33 – Structure of a FCB_SET as confirmation .43
Figure 34 – Structure of the data octet for FCB_SET as requests and confirmations.43
Figure 35 – Structure of a message with a size of more than one word .44
Figure 36 – PDL base protocol machine.45
Figure 37 – Locations of the PDL and the PDL protocol machines in the master and
slaves .48
Figure 38 – PDL protocol machine .49
Figure 39 – TRANSMIT protocol machine .52
Figure 40 – RECEIVE protocol machine.55
Figure 41 – Location of the BLL in the DLL .58
Figure 42 – Interface between PDL and BLL in the layer model .59
Figure 43 – BLL_Data service.60
Figure 44 – Interface between PNM2 and BLL in the layer model.62
Figure 45 – Reset, Set Value and Get Value BLL services .64
Figure 46 – Event BLL service .64
Figure 47 – BLL operating protocol machine of the master.68
Figure 48 – BLL-BAC protocol machine .70
Figure 49 – BLL operating protocol machine of the slave .73
Figure 50 – Location of the MAC in the DLL.74
Figure 51 – Model details of layers 1 and 2.75
Figure 52 – DLPDU cycle of a data sequence without errors .76
Figure 53 – DLPDU cycle of a data sequence with errors.76
Figure 54 – Data sequence DLPDU transmitted by the master .77
Figure 55 – Data sequence DLPDU received by the master .77
Figure 56 – Check sequence DLPDU .77

– 4 – 61158-4-8 © IEC:2007(E)
Figure 57 – Loopback word (LBW) .77
Figure 58 – Checksum status generated by the master .80
Figure 59 – Checksum status received by the master .80
Figure 60 – MAC protocol machine of a master: transmission of a message .81
Figure 61 – MAC protocol machine of a master: receipt of a message .84
Figure 62 – MAC sublayer of a master: data sequence identification.88
Figure 63 – Data sequence DLPDU received by a slave.91
Figure 64 – Data sequence DLPDU transmitted by a slave .91
Figure 65 – Checksum status received by the slave.91
Figure 66 – Checksum status generated by the slave .92
Figure 67 – State transitions of the MAC sublayer of a slave: data sequence.93
Figure 68 – State transitions of the MAC sublayer of a slave: check sequence .94
Figure 69 – Interface between MAC-user and MAC in the layer model .99
Figure 70 – Interactions at the MAC-user interface (master) .100
Figure 71 – Interactions at the MAC-user interface (slave).101
Figure 72 – Interface between MAC and PNM2 in the layer model .104
Figure 73 – Reset, Set Value and Get Value MAC services. 106
Figure 74 – Event MAC service.106
Figure 75 – Location of the PNM2 in the DLL.108
Figure 76 – Interface between PNM2-user and PNM2 in the layer model . 109
Figure 77 – Reset, Set Value, Get Value and Get Active Configuration services . 111
Figure 78 – Event PNM2 service.111
Figure 79 – Set Active Configuration, Get Current Configuration service. 111
Figure 80 – The active_configuration parameter . 115
Figure 81 – Device code structure .118
Figure 82 – Relations between data width, process data channel and parameter
channel .120
Figure 83 – Structure of the control code .121
Figure A.1 – DL-subnetwork configuration in the form of a tree structure . 122
Figure A.2 – State machine for the acquisition of the current configuration . 124
Figure A.3 – State machine for comparing two configurations . 128
Figure A.4 – State machine for comparing one line of two configuration matrices. 130

Table 1 – Primitives issued by DLS-/DLMS-user to DLI.19
Table 2 – Primitives issued by DLI to DLS-/DLMS-user.19
Table 3 – DLI state table – sender transactions .20
Table 4 – DLI state table – receiver transactions .21
Table 5 – Function GetOffset .22
Table 6 – Function GetLength.22
Table 7 – Function GetRemAdd .22
Table 8 – Function GetDlsUserId .22
Table 9 – PDL_Data_Ack.27
Table 10 – PDL_Data_Ack L_status values.27

61158-4-8 © IEC:2007(E) – 5 –
Table 11 – PSM .28
Table 12 – GSM.28
Table 13 – PDL_Reset.32
Table 14 – PDL_Set_Value.32
Table 15 – PDL variables.33
Table 16 – PDL_Get_Value.33
Table 17 – PDL_Event .34
Table 18 – Events.34
Table 19 – Encoding of the L_status .40
Table 20 – FCT code (PDLPDU-Types) .40
Table 21 – State transitions of the PDL base protocol machine.46
Table 22 – Counters of the PDL protocol machines.48
Table 23 – Meaning of the "connection" flag .49
Table 24 – State transitions of the PDL protocol machine .50
Table 25 – State transitions of the TRANSMIT protocol machine .53
Table 26 – State transitions of the RECEIVE protocol machine .55
Table 27 – BLL_Data .61
Table 28 – BLL_Data .64
Table 29 – BLL_Reset .65
Table 30 – BLL_Set_Value .65
Table 31 – BLL variables .66
Table 32 – BLL_Get_Value .66
Table 33 – BLL_Event.66
Table 34 – BLL_Event.67
Table 35 – State transitions of the BLL operating protocol machine of the master.69
Table 36 – State transitions of the BLL-BAC protocol machine.71
Table 37 – State transitions of the BLL operating protocol machine of the slave .73
Table 38 – FCS length and polynomial.78
Table 39 – MAC_Reset .106
Table 40 – MAC_Set_Value .106
Table 41 – MAC variables.107
Table 42 – MAC_Get_Value.107
Table 43 – MAC_Event .107
Table 44 – MAC_Event .108
Table 45 – PNM2_Reset .112
Table 46 – M_status values of the PNM2_Reset .112
Table 47 – PNM2_Set_Value .112
Table 48 – M_status values of the PNM2_Set_Value .113
Table 49 – PNM2_Get_Value.113
Table 50 – M_status values of the PNM2_Get_Value. 113
Table 51 – PNM2_Event .114
Table 52 – MAC Events .114
Table 53 – PNM2_Get_Current_Configuration .114

– 6 – 61158-4-8 © IEC:2007(E)
Table 54 – PNM2_Get_Active_Configuration .115
Table 55 – PNM2_Set_Active_Configuration.116
Table 56 – Data direction.118
Table 57 – Number of the occupied octets in the parameter channel.119
Table 58 – Device class.119
Table 59 – Control data .119
Table 60 – Data width .120
Table 61 – Medium control.121
Table A.1 – DL-subnetwork configuration in the form of a matrix. 123
Table A.2 – Acquire_Configuration.123
Table A.3 – State transitions of the state machine for the acquisition of the current
configuration .125
Table A.4 – Check_Configuration.126
Table A.5 – Compare_Slave .127
Table A.6 – State transitions of the state machine for comparing two configurations . 129
Table A.7 – State transitions of the state machine for comparing one line of two
configuration matrixes .131

61158-4-8 © IEC:2007(E) – 7 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INDUSTRIAL COMMUNICATION NETWORKS –
FIELDBUS SPECIFICATIONS –
Part 4-8: Data-link layer protocol specification – Type 8 elements

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
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2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
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4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
NOTE  Use of some of the associated protocol types is restricted by their intellectual-property-right holders. In all
cases, the commitment to limited release of intellectual-property-rights made by the holders of those rights permits
a particular data-link layer protocol type to be used with physical layer and application layer protocols in Type
combinations as specified explicitly in the IEC 61784 series. Use of the various protocol types in other
combinations may require permission from their respective intellectual-property-right holders.
IEC draws attention to the fact that it is claimed that compliance with this standard may involve the use of patents
as follows, where the [xx] notation indicates the holder of the patent right:
Type 8 and possibly other Types:
DE 41 00 629 C1 [PxC] Steuer- und Datenübertragungsanlage
IEC takes no position concerning the evidence, validity and scope of these patent rights.
The holders of these patent rights have assured IEC that they are willing to negotiate licences under reasonable
and non-discriminatory terms and conditions with applicants throughout the world. In this respect, the statement of
the holders of these patent rights are registered with IEC. Information may be obtained from:
[PxC]: Phoenix Contact GmbH & Co. KG
Referat Patente / Patent Department
Postfach 1341
D-32819 Blomberg
Germany
Attention is drawn to the possibility that some of the elements of this standard may be the subject of patent rights
other than those identified above. IEC shall not be held responsible for identifying any or all such patent rights.

– 8 – 61158-4-8 © IEC:2007(E)
International Standard IEC 61158-4-8 has been prepared by subcommittee 65C: Industrial
networks, of IEC technical committee 65: Industrial-process measurement, control and
automation.
This first edition and its companion parts of the IEC 61158-4 subseries cancel and replace
IEC 61158-4:2003. This edition of this part constitutes an editorial revision.
This edition of IEC 61158-4 includes the following significant changes from the previous
edition:
a) deletion of the former Type 6 fieldbus, and the placeholder for a Type 5 fieldbus data link
layer, for lack of market relevance;
b) addition of new types of fieldbuses;
c) division of this part into multiple parts numbered -4-1, -4-2, …, -4-19.
The text of this standard is based on the following documents:
FDIS Report on voting
65C/474/FDIS 65C/485/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 ISO/IEC Directives, Part 2.
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result 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.
NOTE  The revision of this standard will be synchronized with the other parts of the IEC 61158 series.
The list of all the parts of the IEC 61158 series, under the general title Industrial
communication networks – Fieldbus specifications, can be found on the IEC web site.

61158-4-8 © IEC:2007(E) – 9 –
INTRODUCTION
This part of IEC 61158 is one of a series produced to facilitate the interconnection of
automation system components. It is related to other standards in the set as defined by the
“three-layer” fieldbus reference model described in IEC/TR 61158-1.
The data-link protocol provides the data-link service by making use of the services available
from the physical layer. The primary aim of this standard is to provide a set of rules for
communication expressed in terms of the procedures to be carried out by peer data-link
entities (DLEs) at the time of communication. These rules for communication are intended to
provide a sound basis for development in order to serve a variety of purposes:
a) as a guide for implementors and designers;
b) for use in the testing and procurement of equipment;
c) as part of an agreement for the admittance of systems into the open systems environment;
d) as a refinement to the understanding of time-critical communications within OSI.
This standard is concerned, in particular, with the communication and interworking of sensors,
effectors and other automation devices. By using this standard together with other standards
positioned within the OSI or fieldbus reference models, otherwise incompatible systems may
work together in any combination.

– 10 – 61158-4-8 © IEC:2007(E)
INDUSTRIAL COMMUNICATION NETWORKS –
FIELDBUS SPECIFICATIONS –
Part 4-8: Data-link layer protocol specification – Type 8 elements

1 Scope
1.1 General
The data-link layer provides basic time-critical messaging communications between devices in
an automation environment.
This protocol provides a highly-optimized means of interchanging fixed-length input/output
data and variable-length segmented messages between a single master device and a set of
slave devices interconnected in a loop (ring) topology. The exchange of input/output data is
totally synchronous by configuration, and is unaffected by the messaging traffic.
Devices are addressed implicitly by their position on the loop. The determination of the
number, identity and characteristics of each device can be configured, or can be detected
automatically at start-up.
1.2 Specifications
This standard specifies
a) procedures for the timely transfer of data and control information from one data-link user
entity to a peer user entity, and among the data-link entities forming the distributed data-
link service provider;
b) the structure of the fieldbus DLPDUs used for the transfer of data and control information
by the protocol of this standard, and their representation as physical interface data units.
1.3 Procedures
The procedures are defined in terms of
a) the interactions between peer DL-entities (DLEs) through the exchange of fieldbus
DLPDUs;
b) the interactions between a DL-service (DLS) provider and a DLS-user in the same system
through the exchange of DLS primitives;
c) the interactions between a DLS-provider and a Ph-service provider in the same system
through the exchange of Ph-service primitives.
1.4 Applicability
These procedures are applicable to instances of communication between systems which
support time-critical communications services within the data-link layer of the OSI or fieldbus
reference models, and which require the ability to interconnect in an open systems
interconnection environment.
Profiles provide a simple multi-attribute means of summarizing an implementation’s
capabilities, and thus its applicability to various time-critical communications needs.

61158-4-8 © IEC:2007(E) – 11 –
1.5 Conformance
This standard also specifies conformance requirements for systems implementing these
procedures. This standard does not contain tests to demonstrate compliance with such
requirements.
2 Normative references
The following referenced documents are indispensable for the application of this standard. For
dated references, only the edition cited applies. For undated references, the latest edition of
the referenced document (including any amendments) applies.
IEC 61158-2 (Ed.4.0), Industrial communication networks – Fieldbus specifications – Part 2:
Physical layer specification and service definition
IEC 61158-3-8, Digital data communications for measurement and control – Fieldbus for use
in industrial control systems – Part 3-8: Data link service definition – Type 8 elements
ISO/IEC 7498-1, Information technology – Open Systems Interconnection – Basic Reference
Model: The Basic Model
ISO/IEC 7498-3, Information technology – Open Systems Interconnection – Basic Reference
Model: Naming and addressing
ISO/IEC 10731, Information technology – Open Systems Interconnection – Basic Reference
Model – Conventions for the definition of OSI services
3 Terms, definitions, symbols and abbreviations
For the purposes of this standard, the following terms, definitions, symbols and abbreviations
apply.
3.1 Reference model terms and definitions
This standard is based in part on the concepts developed in ISO/IEC 7498-1 and ISO/IEC
7498-3, and makes use of the following terms defined therein.
3.1.1 DL-address [7498-3]
3.1.2 DL-address-mapping
[7498-1]
3.1.3 DL-connection [7498-1]
3.1.4 DL-connection-end-point [7498-1]
3.1.5 DL-connection-end-point-identifier [7498-1]
3.1.6 DL-data-source [7498-1]
3.1.7 DL-name [7498-3]
3.1.8 DL-protocol
[7498-1]
3.1.9 DL-protocol-connection-identifier [7498-1]
3.1.10 DL-protocol-control-information
[7498-1]
3.1.11 DL-protocol-data-unit [7498-1]

– 12 – 61158-4-8 © IEC:2007(E)
3.1.12 DL-service-connection-identifier [7498-1]
3.1.13 DL-service-data-unit [7498-1]
3.1.14 DL-user-data [7498-1]
3.1.15 layer-management [7498-1]
3.1.16 (N)-entity [7498-1]
DL-entity
Ph-entity
3.1.17 (N)-interface-data-unit [7498-1]
DL-service-data-unit  (N=2)
Ph-interface-data-unit  (N=1)
3.1.18 (N)-layer [7498-1]
DL-layer  (N=2)
Ph-layer  (N=1)
3.1.19 (N)-service [7498-1]
DL-service  (N=2)
Ph-service  (N=1)
3.1.20 (N)-service-access-point [7498-1]
DL-service-access-point  (N=2)
Ph-service-access-point  (N=1)
3.1.21 (N)-service-access-point-address [7498-1]
DL-service-access-point-address  (N=2)
Ph-service-access-point-address  (N=1)
3.1.22 Ph-interface-control-information [7498-1]
3.1.23 Ph-interface-data [7498-1]
3.1.24 primitive name [7498-3]
3.1.25 reset [7498-1]
3.1.26 systems-management [7498-1]

3.2 Service convention terms and definitions
This standard also makes use of the following terms defined in ISO/IEC 10731 as they apply
to the data-link layer:
3.2.1 confirm (primitive);
requestor.deliver (primitive)
3.2.2 DL-service-primitive;
primitive
3.2.3 DL-service-provider
3.2.4 DL-service-user
3.2.5 indication (primitive)
acceptor.deliver (primitive)
61158-4-8 © IEC:2007(E) – 13 –
3.2.6 request (primitive);
requestor.submit (primitive)
3.2.7 response (primitive);
acceptor.submit (primitive)
3.3 Common terms and definitions
NOTE  This subclause contains the common terms and definitions used by Type 8.
3.3.1
link, local link
single DL-subnetwork in which any of the connected DLEs may communicate directly, without
any intervening DL-relaying, whenever all of those DLEs that are participating in an instance
of communication are simultaneously attentive to the DL-subnetwork during the period(s) of
attempted communication
3.3.2
DLSAP
distinctive point at which DL-services are provided by a single DL-entity to a single higher-
layer entity.
NOTE  This definition, derived from ISO/IEC 7498-1, is repeated here to facilitate understanding of the critical
distinction between DLSAPs and their DL-addresses. (See Figure 1.)
DLS-user-entity
DLS-user-entity
DLS-users
DLSAP DLSAP DLSAP
DLSAP-
address DLSAP-
DLSAP-
group DL-
address
addresses
address
DL-layer
DL-entity
PhSA P PhSA P
Ph-layer
NOTE 1  DLSAPs and PhSAPs are depicted as ovals spanning the boundary between two adjacent layers.
NOTE 2  DL-addresses are depicted as designating small gaps (points of access) in the DLL portion of a DLSAP.
NOTE 3  A single DL-entity may have multiple DLSAP-addresses and group DL-addresses associated with a
single DLSAP.
Figure 1 – Relationships of DLSAPs, DLSAP-addresses and group DL-addresses
3.3.3
DL(SAP)-address
either an individual DLSAP-address, designating a single DLSAP of a single DLS-user, or a
group DL-address potentially designating multiple DLSAPs, each of a single DLS-user

– 14 – 61158-4-8 © IEC:2007(E)
NOTE  This terminology is chosen because ISO/IEC 7498-3 does not permit the use of the term DLSAP-address to
designate more than a single DLSAP at a single DLS-user.
3.3.4
extended link
DL-subnetwork, consisting of the maximal set of links interconnected by DL-relays, sharing a
single DL-name (DL-address) space, in which any of the connected DL-entities may
communicate, one with another, either directly or with the assistance of one or more of those
intervening DL-relay entities
NOTE  An extended link may be composed of just a single link.
3.3.5
frame
denigrated synonym for DLPDU
3.3.6
receiving DLS-user
DL-service user that acts as a recipient of DL-user-data
NOTE  A DL-service user can be concurrently both a sending and receiving DLS-user.
3.3.7
sending DLS-user
DL-service user that acts as a source of DL-user-data
3.4 Additional Type 8 definitions
3.4.1 bus coupler
PhL entity which includes or excludes Ph-segments into or from the network
3.4.2 device
slave or master
3.4.3 device code
two octets which characterize the properties of a slave
3.4.4 DLPDU cycle
transaction initiated from the master in which user data or identification/status information is
sent to all slaves and – within the same cycle - received from all slaves
3.4.5 IN data
data received by the master and sent by the slaves
3.4.6 master
DL-entity controlling the data transfer on the network and initiating the media access of the
slaves by starting the DLPDU cycle
3.4.7 OUT data
data sent by the master and received by the slaves
3.4.8 parameter channel
acyclic transmission path using a client/server communication model

61158-4-8 © IEC:2007(E) – 15 –
3.4.9 process data channel
conveyance path allowing a very efficient, high-speed and cyclic transmission of process-
relevant data, between slaves and master
3.4.10 receive update memory
memory area containing the data, which was received from the network
3.4.11 ring segment
group of slaves in consecutive order
3.4.12 ring segment level
nesting level number of a ring segment
3.4.13 slave
DL-entity accessing the medium only after being initiated by the preceding slave or master
3.4.14 transmit update memory
memory area containing the data to be sent across the network
3.4.15 update time
time which passes between two consecutive starts of DLPDU cycles used for data transfer
3.5 Symbols and abbreviations
3.5.1 Type 8 reference model terms
BLL basic link layer
BLLSDU BLL service data unit
BLL_TSDU BLL transmit service data unit
BLL_RSDU BLL receive service data unit
MACSDU MAC service data unit
PDL peripherals data link
PDLSDU PDL service data unit
PhMS Ph-management service
– 16 – 61158-4-8 © IEC:2007(E)
3.5.2 Local variables, timers, counters and queues
add_wait See Table 15
BLL_access_control See Table 31
bus_timeout See Table 31
Ccerr See Table 22
Cconf See Table 22
Ccycle See Table 22
Creq_retry See Table 22
Cswa See Table 22
configuration_valid See Table 31
loopback_word (LBW) See Table 41
max_dlsdu_size_from_req See Table 15
max_dlsdu_size_from_res See Table 15
max_receiving_queue_depth See Table 15
max_sending_queue_depth See Table 15
max_spa_retry See Table 15
max_swa_count See Table 15
start_bus_cycle See Table 15
time_timeout See Table 41
trigger_mode See Table 15
update_time See Table 31
3.5.3 DLPDU classes
DATA data See Table 20
FCB_SET Table 20
frame count bit See
IDL idle See Table 20
RWA read word again See Table 20
SPA send parameter with acknowledge See Table 20
SVA
send value with acknowledge See Table 20
SWA send word again See Table 20

3.5.4 Miscellaneous
AT application triggered
BAC basic access control
61158-4-8 © IEC:2007(E) – 17 –
CO confirmation
CRC cyclic redundancy check
DL-Ph Data Link-Physical (interface)
DLI DL-interface
DSAP destination service access point
FCB frame count bit
FCT function
FMS fieldbus message specification
GSM get shared memory
IN input
L_status link status
LBW loopback word
lsb least significant b
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