1、 g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58Part 3: Low-speed, fault-tolerant, medium-dependent interfaceICS 43.040.15Road vehicles Controller
2、area network (CAN) BRITISH STANDARDBS ISO 11898-3:2006Incorporating corrigendum no. 1BS ISO 11898-3:2006This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 June 2006 BSI 2007ISBN 0 580 48694 XAmendments issued since publicationAmd. No. Date Co
3、mments16919 Corrigendum No. 128 February 2007 Replacement of figure 9Compliance with a British Standard cannot confer immunity from legal obligations.National forewordThis British Standard was published by BSI. It is the UK implementation of ISO 11898-3:2006, incorporating corrigendum December 2006.
4、The UK participation in its preparation was entrusted to Technical Committee AUE/16, Electrical and electronic equipment.A list of organizations represented on AUE/16 can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract.
5、Users are responsible for its correct application. Reference numberISO 11898-3:2006(E)INTERNATIONAL STANDARD ISO11898-3First edition2006-06-01Road vehicles Controller area network (CAN) Part 3: Low-speed, fault-tolerant, medium-dependent interface Vhicules routiers Gestionnaire de rseau de communica
6、tion (CAN) Partie 3: Interface basse vitesse, tolrant les pannes, dpendante du support BS ISO 11898-3:2006ii iiiContents Page Foreword iv Introduction v 1 Scope . 1 2 Terms and definitions. 1 3 Abbreviated terms 3 4 OSI reference model. 4 5 MDI specification 4 5.1 Physical medium. 4 5.2 Physical sig
7、nalling 8 5.3 Electrical specification. 10 5.4 Network specification. 12 6 Physical medium failure definition . 14 6.1 Physical failures 14 6.2 Failure events 15 7 PMA specification. 16 7.1 General. 16 7.2 Timing requirements 16 7.3 Failure management. 20 7.4 Operating modes 23 BS ISO 11898-3:2006iv
8、 Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a
9、technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matter
10、s of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulat
11、ed to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible
12、 for identifying any or all such patent rights. ISO 11898-3 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 3, Electrical and electronic equipment. This first edition of ISO 11898-3 cancels and replaces ISO 11519-2:1994, which has been technically revised. ISO 11898 con
13、sists of the following parts, under the general title Road vehicles Controller area network (CAN): Part 1: Data link layer and physical signalling Part 2: High-speed medium access unit Part 3: Low-speed, fault-tolerant, medium-dependent interface Part 4: Time triggered communication Part 5: High-spe
14、ed medium access unit with low-power mode BS ISO 11898-3:2006vIntroduction ISO 11898, first published in November 1993, covered the controller area network (CAN) data link layer as well as the high-speed physical layer. In the reviewed and restructured ISO 11898: ISO 11898-1 describes the data link
15、layer protocol as well as the medium access control; ISO 11898-2 specifies the high-speed medium access unit (MAU) as well as the medium dependent interface (MDI). ISO 11898-1:2003 and ISO 11898-2:2003 cancel and replace ISO 11898:1993. In addition to the high-speed CAN, the development of the low-s
16、peed CAN, which was originally covered by ISO 11519-2, gained new means such as fault tolerant behaviour. The subject of this part of ISO 11898 is the definition and description of requirements necessary to obtain a fault tolerant behaviour as well as the specification of fault tolerance itself. In
17、particular, it describes the medium dependent interface and parts of the medium access control. BS ISO 11898-3:2006blank1Road vehicles Controller area network (CAN) Part 3: Low-speed, fault-tolerant, medium-dependent interface 1 Scope This part of ISO 11898 specifies characteristics of setting up an
18、 interchange of digital information between electronic control units of road vehicles equipped with the controller area network (CAN) at transmission rates above 40 kBit/s up to 125 kBit/s. The CAN is a serial communication protocol which supports distributed control and multiplexing. This part of I
19、SO 11898 describes the fault tolerant behaviour of low-speed CAN applications, and parts of the physical layer according to the ISO/OSI layer model. The following parts of the physical layer are covered by this part of ISO 11898: medium dependent interface (MDI); physical medium attachment (PMA). In
20、 addition, parts of the physical layer signalling (PLS) and parts of the medium access control (MAC) are also affected by the definitions provided by this part of ISO 11898. All other layers of the OSI model either do not have counterparts within the CAN protocol and are part of the users level or d
21、o not affect the fault tolerant behaviour of the low speed CAN physical layer and therefore are not part of this part of ISO 11898. 2 Terms and definitions For the purposes of this document, the following terms and definitions apply. 2.1 bus topology of a communication network where all nodes are re
22、ached by passive links which allow transmission in both directions 2.2 bus failure failures caused by a malfunction of the physical bus such as interruption, short circuits 2.3 bus value one of two complementary logical values: dominant or recessive NOTE The dominant value represents a logical “0” t
23、he recessive represents a logical “1”. During simultaneous transmission of dominant and recessive bits, the resulting bus value will be dominant. 2.4 bus voltage voltage of the bus line wires CAN_L and CAN_H relative to ground of each individual CAN node NOTE VCAN_Land VCAN_Hdenote the bus voltage.
24、BS ISO 11898-3:20062 2.5 differential voltage Vdiffvoltage seen between the CAN_H and CAN_L lines NOTE Vdiff= VCAN_H VCAN_L2.6 fault free communication mode of operation without loss of information 2.7 fault tolerance ability to operate under specified bus failure conditions at least with a reduced
25、performance EXAMPLE Reduced signal to noise ratio. 2.8 transceiver loop time delay delay time from applying a logical signal to the input on the logical side of the transceiver until it is detected on the output on the logical side of the transceiver 2.9 low power mode operating mode with reduced po
26、wer consumption NOTE A node in low power mode does not disturb communication between other nodes. 2.10 node assembly, connected to the communication line, capable of communicating across the network according to the given communication protocol specification 2.11 normal mode operating mode of a tran
27、sceiver which is actively participating (transmitting and/or receiving) in network communication 2.12 operating capacitance COPoverall capacitance of bus wires and connectors seen by one or more nodes, depending on the topology and properties of the physical media 2.13 physical layer electrical circ
28、uit realization that connects an ECU to the bus 2.14 physical medium (of the bus) pair of wires, parallel or twisted, shielded or unshielded NOTE The individual wires are denoted as CAN_H and CAN_L. 2.15 receiver device that transforms physical signals used for the transmission back into logical inf
29、ormation or data signals BS ISO 11898-3:200632.16 transmitter device that transforms logical information or data signals to electrical signals so that these signals can be transmitted via the physical medium 2.17 transceiver device that adapts logical signals to the physical layer and vice versa 3 A
30、bbreviated terms ACK Acknowledge CAN Controller Area Network CRC Cyclic Redundancy Check CSMA Carrier Sense Multiple Access DLC Data Length Code ECU Electronic Control Unit EOF End of Frame FCE Fault Confinement Entity IC Integrated Circuit LAN Local Area Network LLC Logical Link Control LME Layer M
31、anagement Entity LPDU LLC Protocol Data Unit LSB Least Significant Bit LSDU LLC Service Data Unit LS-MAU Low-Speed Medium Access Unit MAC Medium Access Control MAU Medium Access Unit MDI Medium Dependent Interface MPDU MAC Protocol Data Unit MSB Most Significant Bit MSDU MAC Service Data Unit NRZ No
32、n-Return-to-Zero OSI Open System Interconnection PL Physical Layer PLS Physical Layer Signalling PMA Physical Medium Attachment RTR Remote Transmission Request SOF Start of Frame BS ISO 11898-3:20064 4 OSI reference model According to the OSI reference model shown in Figure 1, the CAN architecture r
33、epresents two layers: data link layer; physical layer. This part of ISO 11898 describes the physical layer of a fault tolerant low-speed CAN transceiver. Only a few influences to the data link layer are given. Figure 1 OSI reference model/CAN layered architecture 5 MDI specification 5.1 Physical med
34、ia 5.1.1 General The physical media used for the transmission of CAN broadcasts shall be a pair of parallel (or twisted) wires, shielded or unshielded, dependent on EMC requirements. The individual wires are denoted as CAN_H and CAN_L. In dominant state, CAN_L has a lower voltage level than in reces
35、sive state, and CAN_H has a higher voltage level than in recessive state. 5.1.2 Node bus connection The two wires CAN_H and CAN_L are terminated by a termination network, which shall be realized by the individual nodes themselves. The overall termination resistance of each line should be greater tha
36、n or equal to 100 . However, the termination resistors value of a designated node should not be below 500 , due to the semiconductor manufacturers constraints. To represent the recessive state CAN_L is terminated to VCCand CAN_H is terminated to GND. Figure 2 illustrates the normal termination of a
37、designated bus node. BS ISO 11898-3:20065Key aOptional. Figure 2 Termination of a single bus node In Figure 2, the termination resistors are denoted as optional. That means that under certain conditions not all nodes need an individual termination, if the requirements of proper overall termination a
38、re fulfilled. 5.1.3 Operating capacitance The following specifications are valid for a simple wiring model which in general is used in automotive applications. It consists of a pair of twisted copper cables which are connected in a topology described in 5.1.4. The following basic model shown in Figu
39、re 3 and 4 is used for the calculations. Key aDriver. bWire. Figure 3 Substitute circuit for bus line BS ISO 11898-3:20066 Key aSymmetric axis. bGround. Figure 4 Operating capacitance referring to network length l The operating capacitance is calculated using Equation 1. COP= l (C + 2C12) + n Cnode+
40、 k Cplug(1) where COPis the operating capacitance; C is the capacitance between the lines and ground referring to the wire length in metres (m); C12is the capacitance between the two wires (which is assumed to be symmetrical) referring to the wire length in metres (m); Cnode is the capacitance of an
41、 attached bus node seen from the bus side; Cplugis the capacitance of one connecting plug; l is the overall network cable length; n is the number of nodes; k is the number of plugs. EXAMPLE A typical value for the operating capacitance referring to the overall network cable length in respect to the
42、exemplary network described below is given by: ()122 120 pF/mCC+= 5.1.4 Medium timing The maximum allowed operating capacitance is limited by network inherent parameters such as: overall termination resistance Rterm; wiring model and topology; communication speed; sample point and voltage thresholds
43、; ground shift, etc. BS ISO 11898-3:20067The following equation provides a method to estimate the maximum allowed operating capacitance. plsyncbitterm OP C0GND th2In( ) lnsttfRCVV V=+(2) where Rtermis the overall network termination resistor (approx. 120 ); COPis the operating capacitance, specified
44、 in Equation (1); Cis the time constant of bus wire; spis the sampling point within a bit, in percent (%); bitis the bit frequency or physical communication speed in bits per second (bit/s); tlis the overall loop delay time of a transceiver device; tsyncis the maximum possible synchronization delay
45、between two nodes; V0is the maximum voltage level of a bus line (approx. 5 V); Vthis the sampling voltage threshold (approx. 1 M 7.2.4 Measurement circuit, GND shift capability Figure 11 illustrates the functional test circuit, which is used to check the ground shift requirements. The test circuit a
46、llows applying different failure cases in combination with a local GND shift in positive and negative direction. The wiring harness between the nodes shall stay as short as possible and shall not exceed 1 m in total. Depending on the applied failure case, the transceiver operates in three main state
47、s: differential driver and receiver; single line operation on CAN_L line; and single line operation on CAN_H line. According the set-up shown in Figure 11, the following bus failure cases shall be applied in combination with a GND shift of up to 1,5 V: no failure; CAN_L wire interrupted; CAN_H wire
48、interrupted; CAN_L shorted to VBat; CAN_H shorted to GND; CAN_L shorted to GND; CAN_H shorted to VBat; and CAN_L shorted to CAN_H. Independently from the applied bus failure and ground shift scenario, all Rx signals shall represent the driven Tx pattern correctly. BS ISO 11898-3:200619Key aSource no
49、de. bDestination node. cGround shift. dBus failure. f1Bus load. f2Bus load. f3Bus load. Figure 11 Test method for transceiver ground shift requirements BS ISO 11898-3:200620 7.3 Failure management 7.3.1 Failure detection To cope with the failures specified in Clause 6, the scheme listed in Tables 11 and 12 shall be used. Table 11 Normal mode event failure detection scheme Event aState bThreshold Timing eD CAN_H VthHxBAT_N 7 s CANH2UBATNcR CA
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