1、BSI Standards PublicationBS EN 14908-2:2014Open Data Communication inBuilding Automation, Controlsand Building Management Control Network ProtocolPart 2: Twisted Pair CommunicationBS EN 14908-2:2014 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of EN 14908-2:2014.It
2、 supersedes BS EN 14908-2:2005 which is withdrawn.The UK participation in its preparation was entrusted to TechnicalCommittee RHE/16, Performance requirements for control systems.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does no
3、t purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. The British Standards Institution 2014. Published by BSI StandardsLimited 2014ISBN 978 0 580 79425 4ICS 35.240.99; 91.140.01; 97.120Compliance with a British Standard cannot confer immun
4、ity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and Strategy Committee on 31 May 2014.Amendments issued since publicationDate Text affectedBS EN 14908-2:2014EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 14908-2 April 2014 ICS 35.240.99;
5、 91.140.01; 97.120 Supersedes EN 14908-2:2005English Version Open Data Communication in Building Automation, Controls and Building Management - Control Network Protocol - Part 2: Twisted Pair Communication Rseau ouvert de communication de donnes pour lautomatisation, la rgulation et la gestion techn
6、ique du btiment - Protocole de contrle du rseau - Partie 2 : Communication par paire torsade Offene Datenkommunikation fr die Gebudeautomation und Gebudemanagement - Gebude-Netzwerk-Protokoll -Teil 2: Kommunikation ber verdrillte Zweidrahtleitungen This European Standard was approved by CEN on 12 Ap
7、ril 2013. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obt
8、ained on application to the CEN-CENELEC Management Centre or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the C
9、EN-CENELEC Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Irelan
10、d, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG CEN-CENELEC Management Centr
11、e: Avenue Marnix 17, B-1000 Brussels 2014 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 14908-2:2014 EBS EN 14908-2:2014EN 14908-2:2014 (E) 2 Contents Foreword 3 Introduction . 4 1 Scope 5 2 Normative references 5 3 Network overv
12、iew 5 4 System specifications . 5 4.1 General aspects . 5 4.2 Cable . 5 4.3 Topology . 5 4.3.1 Free or bus topology . 5 4.3.2 Repeater 6 4.4 Cable termination. 6 4.4.1 Free-topology segment . 6 4.4.2 Bus topology segment 6 4.5 Segment configuration 6 4.6 Power specifications . 7 5 Link power 7 5.1 G
13、eneral 7 5.2 Source . 7 5.3 Power supply requirements 8 5.4 Passive coupler circuit 10 6 Node specifications . 12 6.1 Link power 12 6.2 Hot plugging . 12 6.3 Transmitter/receiver interface to the MAC sub-layer . 12 6.3.1 Physical layer protocol data unit . 12 6.3.2 Frame format 12 6.3.3 Transmit wav
14、eform 13 6.4 Impedance 15 7 Communication parameters . 16 Annex A (informative) Environmental specifications 18 Bibliography 19 BS EN 14908-2:2014EN 14908-2:2014 (E) 3 Foreword This document (EN 14908-2:2014) has been prepared by Technical Committee CEN/TC 247 “Building Automation, Controls and Buil
15、ding Management”, the secretariat of which is held by SNV. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by October 2014 and conflicting national standards shall be withdrawn at the latest by Octob
16、er 2014. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. This document supersedes EN 14908-2:2005. This European Standard is part of a
17、 series of standards for open data transmission in building automation, control and in building management systems. The content of this European Standard covers the data communications used for management, automation/control and field functions. EN 14908-2 is part of a series of European Standards u
18、nder the general title Control Network Protocol (CNP), which comprises the following parts: Part 1: Protocol stack; Part 2: Twisted pair communication; Part 3: Power line channel specification; Part 4: IP-Communication; Part 5: Implementation; Part 6: Application elements. According to the CEN-CENEL
19、EC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Ice
20、land, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. BS EN 14908-2:2014EN 14908-2:2014 (E) 4 Introduction This European Standard has been prepared to provide mechanis
21、ms through which various vendors of building automation, control, and building management systems may exchange information in a standardised way. It defines communication capabilities. This European Standard will be used by all involved in design, manufacture, engineering, installation and commissio
22、ning activities. BS EN 14908-2:2014EN 14908-2:2014 (E) 5 1 Scope This European Standard specifies the control network protocol (CNP) free-topology twisted-pair channel for networked control systems in commercial Building Automation, Controls and Building Management and is used in conjunction with EN
23、 14908-1:2014. The channel supports communication at 78,125 kbit/s between multiple nodes, each of which consists of a transceiver, a protocol processor, an application processor, a power supply, and application electronics. This European Standard covers the complete physical layer (OSI Layer 1), in
24、cluding the interface to the Media Access Control (MAC) sub-layer and the interface to the medium. Parameters that are controlled by other layers but control the operation of the physical layer are also specified. 2 Normative references The following documents, in whole or in part, are normatively r
25、eferenced 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 14908-1:2014, Open Data Communication in Building Automation, Contr
26、ols and Building Management - Control Network Protocol - Part 1: Protocol Stack EN 50173-1, Information technology Generic cabling systems Part 1: General requirements 3 Network overview The CNP free-topology twisted-pair channel supports up to 128 nodes on a single network segment with an optional
27、link power source that supplies DC power to the nodes on the network. The channel is specified to support free-topology wiring, and will accommodate bus, star, loop, or any combination of these topologies. The total network length and number of nodes may be extended by use of CNP channel physical la
28、yer repeaters, or CNP compliant routers. The channel data rate is 78,125 kbit/s. Nodes can be either locally powered or link powered. A link-powered node derives its power from the network. The power is delivered on the same two conductors that carry data. Nodes are polarity-insensitive with respect
29、 to data as well as DC power. A locally powered node derives its power from a local source. The data is transmitted using Differential Manchester encoding, which is polarity-insensitive. 4 System specifications 4.1 General aspects This sub-clause specifies the cable type used, terminations required
30、with bus or free topology, maximum node counts and distances for link and locally powered schemes, and the maximum steady state power that can be drawn from the link power supply. 4.2 Cable The cable shall conform to EN 50173-1. 4.3 Topology 4.3.1 Free or bus topology The network may use either a si
31、ngly-terminated free topology or a doubly-terminated bus topology. BS EN 14908-2:2014EN 14908-2:2014 (E) 6 4.3.2 Repeater Two network segments may be interconnected with a channel physical layer repeater. No more than one physical layer repeater shall be in a path between any two nodes on a network.
32、 Physical layer repeaters shall not be interconnected in such a way as to create a loop. Each port of a physical layer repeater shall meet the specifications stated in 6.2, 6.3.3, and 6.4. The delay through the repeater shall not exceed 36 s. 4.4 Cable termination 4.4.1 Free-topology segment A free-
33、topology segment shall have a single termination. If the segment is locally powered, an RC network as shown in Figure 1 shall be used, with R1 = 52,3 1 %, 1/8 W. The termination may be located anywhere on the segment. If the segment is link-powered, the termination shall be provided by the link powe
34、r source. See Figure 5. The link power source and termination may be located anywhere on the segment. 4.4.2 Bus topology segment A bus topology segment shall have two terminations, one at each end of the bus. If the segment is locally powered, an RC network as shown in Figure 1 shall be used, with R
35、1 = 105 1 %, 1/8 W at each end. If the segment is link-powered, the link power source shall provide one termination. See Figure 5. The other termination shall be an RC network as shown in Figure 1, with R1 = 105 1 %, 1/8 W. Key 1 network connection Figure 1 Termination 4.5 Segment configuration A fr
36、ee-topology twisted-pair channel shall support up to 128 link-powered or 64 locally-powered nodes at a maximum bit error rate of 1 in 100 000. Both types of nodes shall be supported on a given segment, provided the following constraint is met: 128 nodes) poweredlocally ofnumber (2 nodes) poweredlink
37、 ofnumber (1 + Table 1 shows the maximum bus length for a bus-topology segment. Table 2 shows the maximum node-to-node distance and maximum wire length for a free-topology segment. The distance from each node to each of the other nodes and to the link power source shall not exceed the maximum node-t
38、o-node distance. If multiple paths exist, e.g., a loop topology, then the longest path shall be used for the calculations. The maximum wire length is the total amount of wire connected to a network segment. BS EN 14908-2:2014EN 14908-2:2014 (E) 7 Table 1 Bus-topology distance specifications Maximum
39、Bus Length Maximum Stub Length Units 600 3 m Table 2 Free topology distance specifications Maximum Node-to-node Distance Maximum Total Wire length Units 250 450 m 4.6 Power specifications The sum of the steady-state power drawn by all nodes on a segment shall not exceed 36,5 watts. For each branch,
40、the sum of the products of each nodes distance multiplied by that nodes power shall not exceed a constant: + C . . . dP dP dP33 2211(1) where C is a constant, dependent on wire type, taking into account manufacturing tolerance and all other variations except wire temperature; C = 1,9 x 103Wm; Pi= No
41、de power, i.e., the maximum steady-state power drawn by node i from the network, in watts; di= Node distance, i.e., the distance of node i from the link power source, in meters; = 1/(1 + 0,00393 * (temp 25 C), accounting for average wire temperature. 5 Link power 5.1 General A link-powered node deri
42、ves its power from the network. The power is delivered on the same two conductors that carry data. 5.2 Source The link power source shall consist of a passive coupler together with a power supply having special attributes. The requirements for the power supply for proper system operation include its
43、 start-up behaviour, tolerance to direct shorts across its output, and output voltage regulation. A schematic for the coupler is also included. The combination coupler/power supply block diagram is shown in Figure 2. Any deviations from the power supply requirements and coupler schematic (Figure 5)
44、are allowed provided that the link power source design is electrically equivalent. BS EN 14908-2:2014EN 14908-2:2014 (E) 8 Key 1 power supply 7 vin + 2 coupler 8 vin 3 line 9 net + 4 input 10 net 5 neutral 11 network 6 earth 12 output Figure 2 Link Power Source The differential DC output voltage of
45、the link power source shall be 41,0 VDC 42,4 VDC over full operating conditions. Under normal (non-fault) conditions, the link power source shall “centre“ the output voltage with respect to earth ground, resulting in +21 V and 21 V outputs at “Net+“ and “Net-“ respectively. The link power source sha
46、ll recover after a continuous direct short across the output and shall properly restart the link powered network. An earth reference terminal is required if the coupler is not grounded via the power supply. 5.3 Power supply requirements Unless otherwise specified, the power supply specifications in
47、Table 3 shall be met over all combinations of the following conditions: specified coupling circuit connected; line input voltage over full range per specification; network output load = 0 to 1,5 DC amperes. BS EN 14908-2:2014EN 14908-2:2014 (E) 9 Table 3 Power supply requirements Description Conditi
48、ons Specification Line input voltage & indicator Measured at “A“ (see Figure 2) Line voltage as required by application environment. Input Power Applied indicator required - LED or equivalent. Output voltage Measured at “B“ (see Figure 2) 42,4 VDC maximum 42,08 VDC minimum Output voltage regulation
49、response Measured at “B“ 50 % step change in load Output voltage shall recover to within 1 % of its final value in less than 1ms of step change in load. Output reference Measured at “B“ Coupling circuit disconnected Floating with respect to earth. Output ripple voltage (Differential) Measured at “B“ Reference to Figure 2. Spike noise (Differential) Measured at “B“ 50 MHz bandwidth 400 mV peak-to-peak maximum. Output common-mode noise Measured at “B“ with respect to earth 100 m
