CLC/TS 50568-4:2015
(Main)Electricity metering data exchange - Part 4: Lower layer PLC profile using SMITP B-PSK modulation
Electricity metering data exchange - Part 4: Lower layer PLC profile using SMITP B-PSK modulation
This Technical Specification specifies the characteristics of the profile related to Physical and Data Link Layers for communications on LV distribution network between a Concentrator (master node) and one or more slave nodes. The following prescriptions are applied to groups of devices that communicate using low voltage network. Each section of the network is composed by one Concentrator (acting as the master of the section), and one or more primary nodes (A-Nodes). Every A-Node can optionally be associated to one secondary node (B-Node).
Izmenjava podatkov pri merjenju električne energije - Niz DLMS/COSEM - 4. del: Fizična plast, temelječa na modulaciji SMITP B-PSK in plasti SMITP za povezavo podatkov
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-junij-2015
,]PHQMDYDSRGDWNRYSULPHUMHQMXHOHNWULþQHHQHUJLMH1L]'/06&26(0GHO
)L]LþQDSODVWWHPHOMHþDQDPRGXODFLML60,73%36.LQSODVWL60,73]DSRYH]DYR
SRGDWNRY
Electricity metering data exchange - The DLMS/COSEM suite - Part 4: Physical Layer
based on SMITP B-PSK modulation and SMITP Data Link Layer
Ta slovenski standard je istoveten z: CLC/TS 50568-4:2015
ICS:
35.100.10 )L]LþQLVORM Physical layer
35.100.20 Podatkovni povezovalni sloj Data link layer
91.140.50 Sistemi za oskrbo z elektriko Electricity supply systems
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
TECHNICAL SPECIFICATION CLC/TS 50568-4
SPÉCIFICATION TECHNIQUE
TECHNISCHE SPEZIFIKATION
April 2015
ICS 35.240.60; 91.140.50
English Version
Electricity metering data exchange - Part 4: Lower layer PLC
profile using SMITP B-PSK modulation
This Technical Specification was approved by CENELEC on 2014-11-11.
CENELEC members are required to announce the existence of this TS in the same way as for an EN and to make the TS available promptly
at national level in an appropriate form. It is permissible to keep conflicting national standards in force.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2015 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. CLC/TS 50568-4:2015 E
CONTENTS
Foreword . 6
Introduction . 7
1 Scope . 8
2 Normative references . 8
3 Terms, definitions, acronyms and notations . 8
3.1 Terms and definitions . 8
3.2 Acronyms . 8
3.3 Notations . 9
4 Overview . 9
4.1 Communication characterization on LV network . 9
4.2 Communication architecture . 11
4.2.1 Overview . 11
4.2.2 LLC sub-layer . 11
4.2.3 MAC sub-layer . 11
4.2.4 Physical Layer . 12
4.2.4.1 Introduction . 12
4.2.4.2 Modulation and modes . 13
4.2.5 Protocol’s architecture for LV nodes communication . 13
4.3 Requests priority and slave nodes scanning . 14
4.4 Communication disciplines . 14
4.4.1 Service classes . 14
4.4.2 Timers . 15
4.4.3 Discipline types . 16
4.4.3.1 Disciplines of class S . 16
4.4.3.2 Disciplines of class R . 17
4.4.3.3 Disciplines of class RC. 19
5 LLC sub layer . 20
5.1 Primitives and services . 20
5.1.1 DL_Data.request . 20
5.1.1.1 Function . 20
5.1.1.2 Structure . 20
5.1.1.3 Use . 21
5.1.2 DL_Data.confirm . 21
5.1.2.1 Function . 21
5.1.2.2 Structure . 21
5.1.2.3 Use . 22
5.1.3 DL_DATA.indication . 22
5.1.3.1 Function . 22
5.1.3.2 Structure . 22
5.1.3.3 Use . 22
5.2 LLC protocol data unit structure . 22
5.2.1 LLC_PDU format . 22
5.2.2 Control field . 23
5.2.3 Address field . 23
- 3 - CLC/TS 50568-4:2015
5.2.4 Invalid L_PDU . 23
5.3 LLC procedures . 23
5.3.1 Procedure for addressing . 23
5.3.2 Information transmission. 23
5.3.3 Information Reception . 23
5.3.4 Length of an PDU . 23
6 MAC sub layer . 24
6.1 Primitives and services . 24
6.1.1 Primitives . 24
6.1.2 Service classes . 26
6.2 Frame Structure . 27
6.2.1 General . 27
6.2.2 Frame length (LT) . 28
6.2.3 Address (ADDR) . 28
6.2.4 Control (CTL) . 28
6.2.5 Repetition Parameters (RP) . 29
6.2.5.1 General . 29
6.2.5.2 RP field in RIP frames . 29
6.2.5.3 RP field in CRP frames . 30
6.2.6 Information (INF) . 30
6.2.7 Frame checking sequence (SVT) . 30
6.2.8 Example of frame types . 30
6.3 Procedures . 31
6.3.1 Frame filtering . 31
6.3.2 Phase detection . 32
6.3.3 Repetition . 32
6.3.3.1 General . 32
6.3.3.2 Example of repetition procedures . 32
6.3.3.3 Repetition control . 36
7 Physical Layer . 38
7.1 Overview . 38
7.2 P_frame Structure . 38
7.2.1 General . 38
7.2.2 Preamble (PRE) . 39
7.2.3 Unique word (UW) . 39
7.2.4 Mode . 39
7.2.5 P_payload . 39
7.3 Modulation . 39
7.4 Encoder . 40
7.4.1 General . 40
7.4.2 Convolutional Encoder . 40
7.4.3 Convolutional Interleaver . 41
7.5 P_Data services . 43
7.5.1 General . 43
7.5.2 P_Data.request . 43
7.5.3 P_Data.confirm . 43
7.5.4 P_Data.indication . 43
Annex A (informative) SCA address configuration . 44
A.1 Structure of the SCA and ACA addresses . 44
Annex B (informative) Disciplines . 46
B.1 Discipline timers configuration . 46
Annex C (informative) Details on message bit coding . 48
C.1 Example of bit coding . 48
Annex D (normative) SMITP-BPSK specific definitions . 49
D.1 Management of reserved elements . 49
D.2 ECTL (Extended control) structure . 49
List of figures
Figure 1 – Document structure of prTS 50568-4 . 7
Figure 2 – Communication section in a LV line . 10
Figure 3 – A sub-net . 10
Figure 4 – B sub-net . 11
Figure 5 – Data transfer on power line . 12
Figure 6 – Protocol’s architecture in the A sub-net . 13
Figure 7 – Protocol’s architecture in the B sub-net . 13
Figure 8 – Messages exchange in the SAx discipline . 17
Figure 9 – Messages exchange in the RAx discipline . 17
Figure 10 – Messages exchange in the RBx discipline . 18
Figure 11 – Messages exchange in the RCx discipline without repeaters . 19
Figure 12 – Messages exchange in the RCx discipline with repeaters . 20
Figure 13 – LLC frame structure . 23
Figure 14 – Control Field format . 23
Figure 15 – Messages exchange in the Sxx service class . 26
Figure 16 – Messages exchange in the Rxx service class with (b) or without (a) timeout
expiration along the chain, . 27
Figure 17 – MAC frame structure . 27
Figure 18 – RP field in MAC frame (ACA addresses) . 29
Figure 19 – RP field in MAC frame (short form SCA addresses) . 30
Figure 20 – RIP MAC frame . 31
Figure 21 – NOR1 MAC frame . 31
Figure 22 – NOR2 MAC frame . 31
Figure 23 – CRP MAC frame . 31
Figure 24 – Example of repetition procedure using ACA address . 33
Figure 25 – Example of repetition procedure using SCA address . 34
Figure 26 – Example of CRP repetition control procedure . 37
Figure 27 – Data transfer in Physical Layer . 38
Figure 28 – Physical frame (P_frame) structure . 39
Figure 29 – Convolutional encoding of the P_payload . 40
Figure 30 – Convolutional Encoder . 40
- 5 - CLC/TS 50568-4:2015
Figure 31 – Convolutional Interleaver . 41
Figure 32 – P_Data services . 43
Figure A.1 – SCA address structure . 44
Figure A.2 – ACA address structure . 44
Figure C.1 – Frames encapsulation example . 48
List of tables
Table 1 – Service classes in communication disciplines . 15
Table 2 – MA_EVENT.indication parameters . 26
Table 3 – CTL field coding in MAC frame . 28
Table 4 – Example of interleaving . 42
Table 5 – Shift registers initial condition. 43
Table B.1 – Subfield dddd and maximum number of received bytes in A and B subnets for
disciplines S, RA and RB. . 46
Table B.2 – Subfield ddd and number of time slots for RC disciplines. . 46
Foreword
This document (CLC/TS 50568-4:2015) has been prepared by CLC/TC 13, "Electrical energy measurement
and control".
The following date is fixed:
• latest date by which the existence of (doa) 2015-07-24
this document has to be announced
at national level
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such patent rights.
This document has been prepared under a mandate given to CENELEC by the European Commission and
the European Free Trade Association.
The European Committee for Electrotechnical Standardization (CENELEC) draws attention to the fact
that it is claimed that compliance with this International Standard may involve the use of a
maintenance service concerning the stack of protocols on which the present Technical Specification
CLC/TS 50568 is based.
The CENELEC takes no position concerning the evidence, validity and scope of this maintenance
service.
The provider of the maintenance service has assured the CENELEC that he is willing to provide
services under reasonable and non-discriminatory terms and conditions for applicants throughout the
world. In this respect, the statement of the provider of the maintenance service is registered with the
CENELEC. Information may be obtained from:
Meters and More Open Technologies
Brussels/Belgium
www.metersandmore.eu
- 7 - CLC/TS 50568-4:2015
Introduction
This Technical Specification is based on the results of the European OPEN Meter project, Topic
Energy 2008.7.1.1, Project no.: 226369, www.openmeter.com.
According to the structure of the CLC/TS 50568 documentation, this document is positioned as
highlighted in the following figure:
Figure 1 – Document structure of CLC/TS 50568-4
1 Scope
This Technical Specification specifies the characteristics of the profile related to Physical and Data
Link Layers for communications on LV distribution network between a Concentrator (master node)
and one or more slave nodes.
The following prescriptions are applied to groups of devices that communicate using low voltage
network. Each section of the network is composed by one Concentrator (acting as the master of the
section), and one or more primary nodes (A-Nodes). Every A-Node can optionally be associated to
one secondary node (B-Node).
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
EN 50065-1, Signalling on low-voltage electrical installations in the frequency range 3 kHz to
148,5 kHz – Part 1: General requirements, frequency band and electromagnetic disturbances
3 Terms, definitions, acronyms and notations
3.1 Terms and definitions
For the purpose of this document, the following terms and definitions apply:
3.1.1
concentrator section
identification code of the network managed by the concentrator
3.1.2
node subsection
identification code of the sub network within the network identified by concentrator section
3.1.3
node progressive
unique node ID within the node sub section
3.1.4
upper layers
every communication stack layer except PHY, MAC and LLC
3.2 Acronyms
For the purpose of this document, the following acronyms apply:
ACA: Absolute Communication Address
B-PSK: Binary Phase Shift Keying
CRC: Cyclic Redundancy Check
D-L: Data-Link
ECC: Encryption Coding Control
ECTL: Extended Control
HDLC: High-level data link control procedures
LLC: Logical Link Control
LSb: Least Significant bit
LSB: Least Significant Byte
LSDU: LLC Service Data Unit
LV: Low Voltage
- 9 - CLC/TS 50568-4:2015
MAC: Medium Access Control
MAU: Mains Attachment Unit
MSb: Most Significant bit
MSB: Most Significant Byte
NDM: Normal disconnect mode, one of the non-operational data link mode of HDLC
NM: Network Management
Ph: Physical
PLS: Physical Signalling
PRE: Preamble
PSK: Phase Shift Keying
SAP: Service Access Point
SCA: Section Communication Address
UL: Upper Layer
UW: Unique Word
3.3 Notations
For the purpose of this document, the following notations apply:
– 1 byte = 8 bits (or octet);
– byte/field name representation: capital letters;
– bit name representation: small letters;
– bits transmission sequence related to their representation: first bit on the left = first transmitted
bit;
– bit transmission order related to their weight: least significant bit = first transmitted bit;
– bytes transmission sequence related to their representation: first byte on the left = first
transmitted byte;
– bytes transmission order related to their weight: least significant byte = first transmitted byte;
– fields transmission sequence related to their representation: first field on the left = first
transmitted field;
– fields transmission order related to their weight: least significant field= first transmitted field;
– a frame/message is “upstream” if it is logically sent from centre to periphery;
– a frame/message is “downstream” if it is logically sent from periphery to centre.
4 Overview
4.1 Communication characterization on LV network
The Physical Layer configuration on LV network is considered as a multi-point connection of nodes
operating in half-duplex mode. So, access rules are required in order to avoid nodes transmission
collisions.
Furthermore, it has to be considered that LV network cannot be treated as a normal broadcast
medium, because standing-waves phenomena and most of all signal attenuation may make direct
communication between couple of nodes impossible.
In order to obtain a virtually direct communication, between any couple of nodes, the protocol
functionalities shall foresee the repetition technique. Figure 2 shows the reference scheme of a LV
line portion, which is identified as communication section. A LV network controlled by a Concentrator
is composed by a set of branch-connected sections of this kind:
Figure 2 – Communication section in a LV line
where:
– information exchanging is required either between Concentrator and any node, or between an A-
Node and the associated B-Node;
– message transferring shall always happen on the A-Node electric connection phase. In case of
polyphase meter, communication shall always happen through one of the three phases, the same
one for all communications;
– each A-Node and B-Node has its own unique address.
There are the following two types of sub-nets. Each one is unbalanced (the initiation of transmission
procedure is limited to a master or a sub-net master station), with one or more slave nodes.
A sub-net
Figure 3 – A sub-net
Within A sub-net, communications between Concentrator (master station for this sub-net) and any
node (slave), with single or group addressing, are defined. This sub-net can use repetition.
- 11 - CLC/TS 50568-4:2015
B sub-net
Figure 4 – B sub-net
Within B sub-net, communications between A-Node (master station for this sub-net) and the
associated B-Node (slave) are defined. This sub-net does not foresee repetition.
The profile of protocols to be used has to reach the following objectives:
– to satisfy application requirements in terms of efficiency and effectiveness;
– to reduce data amount to supply to equipment during network configuration stage as much as
possible;
– to make efficient use of the channel;
– to support all the group addressing performances, according with what is required by
applications, also in presence of a network with repetitions.
4.2 Communication architecture
4.2.1 Overview
This document describes a lower layer profile that includes the Logical Link Control, the Medium
Access Control and the Physical Layers.
The repetition functionality is inserted in the MAC sub-layer, in order to guarantee to LLC sub-layer
the direct exchange between Concentrator master node and each of the slave nodes.
4.2.2 LLC sub-layer
LLC sub-layer interfaces the Upper Layers on the upper side and the MAC sub-layer on the lower
side. It is required to support the following functions:
– it is responsible about the execution of end-to-end exchange procedures to guarantee a correct
access procedure that avoids any possible collision on the network (in any moment a single node
can ask a transmission request on MAC level); it manages access times to the LV communication
on the master node;
– it operates end-to-end between master nodes and all the slave nodes; it offers a connectionless-
type service to equipment applications, according with the kind of exchange procedure required;
– in master nodes, it indicates to Upper Layer the network availability; the transmission of another
message can be requested, upon reception of this indication;
– in master nodes, it manages re-transmissions (retry) on exchanges with expected answer.
The mechanisms to provide the above listed features are left to the implementers of the Master node
without any limitation on interoperability.
LLC sub-layer does not check the correctness of the used disciplines (see 4.4); it’s up to the upper
layer to select it properly.
4.2.3 MAC sub-layer
In this sub-layer, the repetition functionalities (MACre) are distinguished from the physical interfacing
functionalities (MACph).
MACre functions:
– it operates end-to-end between master node and all the network slave nodes offering a
connectionless service;
– it uses the services supplied by MACph to transfer frames with the limited goal to provide
necessary functions for the packet transfer between a master node and a slave final node on a
multi-point Data-Link with hidden stations (slave nodes that need one or more repeaters to
communicate with the master node);
– it manages the timers of busy network condition in master nodes and repeaters.
MACph functions:
– frames encapsulation;
– received frames filtering, on the basis of a single or grouped address;
– frame errors detection.
The access mode to the physical medium is half duplex. MACph is capable to distinguish correct
frames from not correct ones, but it does not handle error recovery. A wrong frame is rejected.
MACph also handles connection electric phase detection of LV: the correlation between frame and
LV phase shall happen:
– in transmitting mode on Concentrator and on A-Node repeater;
– in receiving mode on all the A-Nodes;
while the correlation shall happen in both mode types on B-Nodes.
NOTE The phase detection algorithm depends on the specific implementation adopted by manufacturers.
4.2.4 Physical Layer
4.2.4.1 Introduction
The Physical Layer (PHY) defines the method used to transfer data over the physical medium (power
line), by performing:
– encapsulation of data in a physical frame;
– modulation / demodulation of the physical frame using B-PSK scheme.
Figure 5 – Data transfer on power line
- 13 - CLC/TS 50568-4:2015
Additionally, the Physical Layer provides following services:
– bit and byte synchronization;
– Signal to noise ratio (SNR) estimation. When implemented, this functionality may be used for
Network Management purposes (out of the scope of this document).
4.2.4.2 Modulation and modes
The modulation is a B-PSK (Binary Phase Shift Keying) with a symbol rate equal to 9600 symbol/s.
To improve the robustness of the communication in noisy environments, an error correction
technique is implemented through the use of a convolutional code with rate ½ and an interleaver.
Therefore, the resulting bit-rate is 4800 bps.
4.2.5 Protocol’s architecture for LV nodes communication
Referring to LV sub-nets, the following figures show the protocol stack in each equipment:
in A sub-net:
Figure 6 – Protocol’s architecture in the A sub-net
in B sub-net:
Figure 7 – Protocol’s architecture in the B sub-net
Each node type shall own a protocol profile including all the sub-layers required by the sub-nets in
which the node works.
Sub-layers required to Concentrator:
– LLC manages LLC services as master for A sub-net;
– MAC manages MAC services as master for A sub-net.
Sub-layers required to a A-Node:
– LLC manages LLC services as slave for A sub-net, and LLC services as master for B sub-net;
– MAC manages MAC services as slave for A sub-net, and MAC services as master (without
repetition) for B sub-net.
These are the sub-layers requested to B-Node:
– LLC manages LLC services as slave for B sub-net;
– MAC manages MAC services as slave (without phase detection and repetition) for B sub-net.
4.3 Requests priority and slave nodes scanning
The LLC sublayer of concentrator receives and processes requests coming from UL in FIFO order
without priority handling.
NOTE Manufacturers can also implement procedures within concentrator in order to differently manage requests from
central system and messages towards slave nodes.
4.4 Communication disciplines
4.4.1 Service classes
The communication on LV network shall happen within the following three classes of basic services:
– S Class – Send/Noreply (Sxx):
message transmission without either response or acknowledge requiring.
– RA Class – Request/Respond (RAx):
message transmission requiring a response from an A Node. The layers above Data-Link that
receive a message belonging to this class shall always generate a response. The response is
never generated by remote node Data-Link Layer.
– RB Class – Request/Respond (RBx):
message transmission requiring a response from an B Node. The layers above Data-Link that
receive a message belonging to this class shall always generate a response. The response is
never generated by remote node Data-Link Layer.
– RC Class – Request/MultiRespond (RCx):
message transmission accepting several responses. The layers above Data-Link that receive a
message belonging to this class, if enabled, shall always generate a response. The response will
be delayed as defined in 4.4.2. So the sender having multiple addressed targets (multicast
address, or several targets which are entitled to answer to the same command), can receive
several responses.
- 15 - CLC/TS 50568-4:2015
Table 1 – Service classes in communication disciplines
Class Function Description
Send message without
S Send/Noreplay
response/ack
Send message with
RA Request/Respond response to a node in A
subnetwork.
Send message with
RB Request/Respond response to a node in B
subnetwork.
Send message with
RC Request/MultiRespond
(multiple) response
The communication disciplines are defined for each service class on the basis of service type
requested by Upper Layer to LLC, and then by LLC to MAC; these disciplines are further on
subdivided in sub-disciplines (see 4.4.3). Since the type of the request coming from the UL shall be
known to choose the proper communication discipline and so to compute the right value of the
timers, it is Upper Layer care to configure the discipline in the LLC and MAC sub layers (see 5.1.1
and 6.1.1).
Supervision timers (T) within master node and intermediate repeaters are defined for each class,
concerning:
– about master: maximum waiting time to recover the network access in case of no response
(because not expected or lost);
– about repeaters: response frame (when expected) waiting time.
Supervision timers are managed at MAC level, as soon as the supervision timer expires the
information is propagated by the MAC sublayer itself, along the repetition chain of the message, to
the Master node, which shall issue a MA_EVENT.indication primitive. At the reception of the
MA_EVENT.indication the Master node LLC sublayer shall generate an appropriate
DL_DATA.confirm with negative result.
Meaning of parameters that are in T function expressions is illustrated in the next subclause.
4.4.2 Timers
The next subclauses will use the parameters described below to define the timers:
T=Ta+Tb
where:
T is the total transaction time;
Ta is the A sub-net utilization time;
Tb is the B sub-net utilization time.
Ta and Tb take a different value according with procedure type.
The following variables are defined:
nbTXa is the number of bits to transmit on A sub-net;
nbRXa is the number of bits to receive on A sub-net;
nbTXb is the number of bits to transmit on B sub-net;
nbRXb is the number of bits to receive on B sub-net;
tbit is the one bit time;
nbadd is the address field bit number;
r is the number of subsequent repeaters.
In order to calculate the supervision timer, the node (Master or repeater) shall use as nbRXa and
nbRXb the maximum number of bytes allowed by the used discipline, as described in Tables B.1 and
B.2.
An additional value shall be added to Ta and Tb; this value depends on processing time of every
device involved in the transmission (Tel) and on other delays that are typical of particular scenario.
This additional value is needed to provide a safety margin to avoid collision in network accessing.
Tel is the processing time;
delay is the further delay for specific reasons.
The estimate of above-mentioned time shall also consider next hypothesis:
– nbadd parameter value can be equal to 12 or 48, depending on the adopted addressing policy
(see 6.2.5.2);
– Concentrator and repeaters know the size of all the messages involved in a transaction, or
however their maximum size;
– in case of a request with one or more possible response (by different sizes), the maximum size is
considered;
– in case of requests to a node that do not foresee response, the repeaters shall not activate timers
after the frame has been sent;
– delay introduced by each device for internal processing shall not be greater than 10 ms.
The repeaters shall be provided with a Tb and nbRXa value associated to current transaction.
The information about transaction type (or adopted discipline) is transmitted in the MAC frame
control field. For the adopted discipline coding, refer to Annex B.
Since a known maximum size for the reply message corresponds to each activity, also the maximum
waiting time for the busy network is known. So, the A-Node repeater is able to calculate its own
timer.
4.4.3 Discipline types
4.4.3.1 Disciplines of class S
SAx discipline.
This discipline involves the A sub-net:
- 17 - CLC/TS 50568-4:2015
Figure 8 – Messages exchange in the SAx discipline
The total transaction time has the following value:
T=[nbTX⋅(r+1)+nbadd⋅r⋅(r+1)/ 2]⋅tbit+Tel⋅r
Since no response is expected, repeaters do not have to activate a response-waiting timer.
This procedure foresees a supervision timeout T on the Concentrator. LLC notifies timeout expiry to
the Upper Layer and only at T expiry accepts the request to send a new message.
LLC of the involved A-Node delivers received message toUL, and refuses further transmission
requests.
4.4.3.2 Disciplines of class R
RAx Discipline
This discipline involves only A sub-net:
Figure 9 – Messages exchange in the RAx discipline
The total transaction time has the following value:
T=[(nbTX+nbRX)⋅(r+1)+nbadd⋅r⋅(r+1)/ 2]⋅tbit+(2r+1)⋅Tel+delay
This procedure foresees a Concentrator supervision timeout T, which shall consider the response by
slave final node; so LLC accepts a new message from Upper Layer only at reception of reply frame
by slave final node or at temporization expiry. The temporization expiry is notified to the Upper
Layers through DL-DATA.confirm service, as explained in 5.1.2.
The duty of LLC is to pass over to UL the response message or the eventual signalling of expired
supervision timeout T.
The duty of MAC is to manage supervision timeout T.
LLC sub-layers of eventual repeaters are not involved.
MAC of repeaters will follow the procedures that are foreseen by repetition within this discipline, by
activating a supervision timer on repetition according with the defined expression.
LLC in slave final nodes delivers the received message to Upper Layer and prepares itself to satisfy
a request, from UL, to send a response on the network.
RBx Discipline
It involves A and B sub-nets.
Within B sub-net the discipline is Request/Respond type:
Figure 10 – Messages exchange in the RBx discipline
The total transaction time has the following value:
T=[(nbTXa+nbRXa)⋅(r+1)+nbadd⋅r⋅(r+1)/ 2+(nbTXb+nbRXb)]⋅tbit+(2r+1)⋅Tel+ 2⋅Tel+delay
The master supervision timeout T shall consider the message propagation, the response on B sub-
net and the response of A-Node to Concentrator.
LLC on Concentrator has the task to give UL the response or the eventual indication of supervision
timeout T expiry. It can accept a new message from Upper Layer only at reception of slave final node
LLC response frame or at T temporization expiry.
The LLC of eventual repeaters are not involved.
The repeaters MAC will follow the procedures foreseen by repetition within this discipline, by
activating a repetition supervision timer according with the defined expression.
The LLC sub-layer in slave final node delivers received message to Upper Layer, waits for response
message from Upper Layer and sends it on network.
Since B-Node should send a response, this discipline foresees a supervision timeout T even on A-
Node. If the response arrives, LLC (A-Node is master of B sub-net) delivers the response to UL,
otherwise it indicates timeout expiry.
- 19 - CLC/TS 50568-4:2015
4.4.3.3 Disciplines of class RC
RCx Discipline without repeaters
The sender sending a message with RCx discipline waits several responses. Typically the sender
sends a request to a multicast address.
To avoid that responses by several responders will collide, the target will respond in delayed mode.
The target calculates a random number between 1 and N and responds in the slot time identified by
the random number. The max number of the slots is N. The time of a slot (TSlot) is defined by a
parameter inside the target (starting default by manufacturer: 250 ms).
In this case the time out calculation is simpler. Assuming that TSlot is correctly calculated:
T= ExT=(N+1)⋅TSlot
where:
ExT is the ExtraTime;
N is the max number of the slots (as defined in Annex B: 8, 16, 32, 64);
TSlot is the time of a slot.
TSlot shall be:
TSlot>(nbTX+nbRX)⋅tbit+Tel+ST
where:
ST is the safe time.
EXAMPLE:
First default value used is 250 ms, considering that the used message is a short one (less than 20
bytes payload).
That time gives a 100 ms margin (ST) at 2400 baud.
Figure 11 – Messages exchange in the RCx discipline without repeaters
RCx discipline with repeaters
The target of the message sent by concentrator is a A node that has to send the message using the
above defined “Request/MultiRespond” discipline toward the meters below in the A subnet and sends
the response to the concentrator when the time out expires. During the time out expiring time, it
receives some responses by final targets.
To define the correct time out, the following disciplines are used:
– the discipline defined in the field dddd of CTL byte from the first until the last repeater;
– Request/MultiRespond discipline further down the last repeater.
Figure 12 – Messages exchange in the RCx discipline with repeaters
The total transaction time has the following value:
T=[(nbTXa+nbRXa)⋅(r+1)+nbadd⋅r⋅(r+1)/ 2]⋅tbit+ ExT+(2r+1)⋅Tel+ 2⋅Tel+delay
5 LLC sub layer
NOTE This section covers the SMITP Logical Link Control services, which are specified by describing the information flow
between the Upper Layers and the MAC sub layer, w
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.
Loading comments...