1、 Reference number ISO/IEC 14908-2:2012(E) ISO/IEC 2012INTERNATIONAL STANDARD ISO/IEC 14908-2 First edition 2012-02-15 Information technology Control network protocol Part 2: Twisted pair communication Technologies de linformation Protocole de rseau de contrle Partie 2: Communication de pair torsade
2、ISO/IEC 14908-2:2012(E) COPYRIGHT PROTECTED DOCUMENT ISO/IEC 2012 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
3、 either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO/IEC 2012 All rights reserved - 2 - Content
4、s Introduction .5 1 Scope.7 2 Normative references.7 3 Network overview .7 4 System specifications7 4.1 General aspects7 4.2 Cable8 4.3 Topology .8 4.3.1 Free or bus topology8 4.3.2 Repeater 8 4.4 Cable Termination 8 4.4.1 Free-topology segment8 4.4.2 Bus topology segment.8 4.5 Segment configuration
5、.9 4.6 Power specifications9 5 Link power 9 5.1 General 9 5.2 Source . 10 5.3 Power supply requirements. 10 5.4 Passive coupler circuit. 13 6 Node specifications 14 6.1 Link power 14 6.2 Hot plugging . 14 6.3 Transmitter/receiver interface to the MAC sub-layer. 14 6.3.1 Physical layer protocol data
6、unit. 14 6.3.2 Frame format. 15 6.3.3 Transmit waveform. 16 6.4 Impedance. 19 7 Communication parameters 20 Annex A (informative). 21 Environmental specifications. 21 Bibliography 22 Figures Figure 1 Termination8 Figure 2 Link Power Source.10 Figure 3 Power supply output ripple voltage requirement 1
7、1 Figure 4 Power supply startup interval behavior 12 Figure 5 Coupler circuit schematic.13 Figure 6 Physical layer protocol data unit 15 14908-2 ISO/IEC:2012 (E) - 3 - Figure 7 Frame format for compliant transmitter. .15 Figure 8 Idealised transmit waveform - zero bit16 Figure 9 Idealised transmit w
8、aveform - one bit.17 Figure 10 Maximum voltage spectrum over frequency relative to peak18 Figure 11 Minimum impedance powered and unpowered node19 Tables Table 1 Bus-Topology Distance Specifications 9 Table 2 Free-Topology distance specifications 9 Table 3 Power supply requirements.11 Table 4 Couple
9、r circuit bill of materials 14 Table 5 Link power requirements.14 Table 6 Communication parameters for interoperable transceiver.20 Table A. 1 Representative environmental specifications for nodes .21 14908-2 ISO/IEC:2012 (E) - 4 - Foreword ISO (the International Organization for Standardization) an
10、d IEC (the International Electrotechnical Commission) form the specialized system for worldwide standardization. National bodies that are members of ISO or IEC participate in the development of International Standards through technical committees established by the respective organization to deal wi
11、th particular fields of technical activity. ISO and IEC technical committees collaborate in fields of mutual interest. Other international organizations, governmental and non-governmental, in liaison with ISO and IEC, also take part in the work. In the field of information technology, ISO and IEC ha
12、ve established a joint technical committee, ISO/IEC JTC 1. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of the joint technical committee is to prepare International Standards. Draft International Standards adopted by the join
13、t technical committee are circulated to national bodies for voting. Publication as an International Standard requires approval by at least 75 % of the national bodies casting a vote. ISO/IEC 14908-2 was prepared by CEN/TC 247 and was adopted, under a special “fast-track procedure”, by Joint Technica
14、l Committee ISO/IEC JTC 1, Information technology, in parallel with its approval by the national bodies of ISO and IEC. ISO/IEC 14908 consists of the following parts, under the general title Information technology Control network protocol: Part 1: Protocol stack Part 2: Twisted pair communication Pa
15、rt 3: Power line channel specification Part 4: IP communication 14908-2 ISO/IEC:2012 (E) - 5 - Introduction This International Standard has been prepared to provide mechanisms through which various vendors of local area control networks may exchange information in a standardised way. It defines comm
16、unication capabilities. This International Standard is to be used by all involved in design, manufacture, engineering, installation and commissioning activities. Echelon Corporation, 4015 Meridian Avenue, San Jose, CA 94304, USA, phone +1-408- 938-5234, fax: +1-408-790-3800 http:/. Attention is draw
17、n to the possibility that some of the elements of this International Standard may be the subject of patent rights other than those identified above. ISO and IEC shall not be held responsible for identifying any or all such patent rights. 14908-2 ISO/IEC:2012 (E) The International Organization for St
18、andardization (ISO) and International Electrotechnical Commission (IEC) draw attention to the fact that it is claimed that compliance with this International Standard may involve the use of patents held by Echelon Corporation. The ISO and IEC take no position concerning the evidence, validity and sc
19、ope of this patent right. The holder of this putative patent right has assured the ISO and 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 holder of the putative p
20、atent rights is registered with the ISO and IEC. Information may be obtained from: - 7 - INFORMATION TECHNOLOGY CONTROL NETWORK PROTOCOL Part 2: Twisted pair communication 1 Scope This International Standard covers the complete physical layer (OSI Layer 1), including the interface to the Media Acces
21、s 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 referenced documents are indispensable for the application of this International Standard
22、. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO/IEC 14908-1:2012, Information technology Control network protocol Part 1: Protocol stack. ISO/IEC 15018, Information technology - Gene
23、ric cabling for homes. 3 Network overview 4 System specifications 4.1 General aspects 14908-2 ISO/IEC:2012 (E) This section specifies the cable type used, terminations required with bus or free topology, maximum node counts and distances for link and locally powered schemes, and the maximum steady s
24、tate power that can be drawn from the link power supply. The CNP free-topology twisted-pair channel supports up to 128 nodes on a single network segment with an optional link power source that supplies DC power to the nodes on the network. The channel is specified to support free-topology wiring, an
25、d 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 layer repeaters, or CNP compliant routers. The channel data rate is 78,125 kbit/s. Nodes can be either locally powered or link power
26、ed. 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 to data as well as DC power. A locally powered node derives its power from a local source. The data is transmitted using Differen
27、tial Manchester encoding, which is polarity-insensitive. This International Standard specifies the control network protocol (CNP) free-topology twisted-pair channel for networked control systems in local area control networks and is used in conjunction with ISO/IEC 14908-1. The channel supports comm
28、unication 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. - 8 - 4.2 Cable The cable shall conform to 9.4 of ISO/IEC 15018:2004. 4.3 Topology 4.3.1 Free or bus topology The ne
29、twork may use either a singly-terminated free topology or a doubly-terminated bus topology. 4.3.2 Repeater 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-topolo
30、gy 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 R1 = 105 1 %, 1/8 W at each end. If the segment is link-powered, the link power source shall
31、 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 14908-2 ISO/IEC:2012 (E) A free-topology segment shall have a single termination. If the segment is locally powered, an R
32、C 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 power source. See Figure 5. The link power source and termination may be located anywhere on
33、the segment. 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. Physical layer repeaters shall not be interconnected in such a way as to create a loop. - 9 - 4.5 Segment co
34、nfiguration 128 nodes) powered locally of number (2 nodes) powered link of number (1 Table 1 shows the maximum bus length for a bus-topology segment. Table 1 Bus-Topology Distance Specifications Maximum bus length Maximum stub length Units 600 3 m Table 2 Free-Topology distance specifications Maximu
35、m node-to-node distance Maximum total wire length Units 250 450 m 4.6 Power specifications C . . . d P d P d P3 3 2 2 1 1(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 10 3Wm; P i= Node power,
36、 i.e., the maximum steady-state power drawn by node i f rom the network, in watts; d i= Node distance, i.e., the distance of node i from the link power source, in meters; = 1/(1 + 0,003 93 * (temp C- 25C), accounting for average wire temperature. 5 Link power 14908-2 ISO/IEC:2012 (E) 5.1 General A l
37、ink-powered node derives its power from the network. The power is delivered on the same two conductors that carry data. The sum of the steady-state power drawn by all nodes on a segment shall not exceed 36,5 W. For each branch, the sum of the products of each nodes distance multiplied by that nodes
38、power shall not exceed a constant: 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-to-node distance. If multiple paths exist, e.g
39、., 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. A free-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
40、100 000. Both types of nodes shall be supported on a given segment, provided the following constraint is met: - 10 - 5.2 Source Key 1 Power supply 2 Coupler 3 Line 4 Input 5 Neutral 6 Earth 7 Vin + 8 Vin 9 Net + 10 Net 11 Network 12 Output Figure 2 Link Power Source An earth reference terminal is re
41、quired if the coupler is not grounded via the power supply. 5.3 Power supply requirements Unless otherwise specified, the power supply specifications in Table 3 shall be met over all combinations of the following conditions: Specified coupling circuit connected Line input voltage over full range per
42、 specification Network output load = (0 to 1,5) A D.C. 14908-2 ISO/IEC:2012 (E) The differential DC output voltage of the link power source shall be 41,0 V DC 42,4 V DC over full operating conditions. Under normal (non-fault) conditions, the link power source shall “centre“ the output voltage with r
43、espect to earth ground, resulting in +21 V and 21 V outputs at “Net+“ and “Net-“ respectively. The link power source shall recover after a continuous direct short across the output and shall properly restart the link powered network. The link power source shall consist of a passive coupler together
44、with a power supply having special attributes. The requirements for the power supply for proper system operation include its 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 su
45、pply block diagram is shown in Figure 2. Any deviations from the power supply requirements and coupler schematic (Figure 5) are allowed provided that the link power source design is electrically equivalent. - 11 - Table 3 Power supply requirements Description Conditions Specification Line input volt
46、age & 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 V DC maximum 42,08 V DC minimum Output voltage regulation response Measured at “B“ 50 % s
47、tep change in load Output voltage must 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 Figure 2. Spike noise
48、 (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 mV peak-to-peak maximum. Continuous output current capability Measured at “B“ 0 to 1,5 A DC Output start-up interval behaviour Start-up or recovery from ou
49、tput short circuit or over- current fault Measured at “B“ Reference Figure 4. Short circuit output protection Continuous short circuit at output for any duration Must recover after fault is cleared according to “Output start-up interval behaviour“ specification. Single fault tolerance Any single component failure as open or short Measured at “B“ “Vin+“ - “Vin-“ 42,4 V. |
