SAE J 1939-14-2016 Physical Layer 500 Kbps.pdf

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1、_SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising theref

2、rom, is the sole responsibility of the user.”SAE reviews each technical report at least every five years at which time it may be revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions.Copyright 2016 SAE InternationalAll rights reserved. No part of this publi

3、cation may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE.TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada)Tel: +1 724-776-4970 (out

4、side USA)Fax: 724-776-0790Email: CustomerServicesae.orgSAE WEB ADDRESS: http:/www.sae.orgSAE values your input. To provide feedback on this Technical Report, please visitHTTP:/STANDARDS.SAE.ORG/J1939/14_201612SURFACE VEHICLERECOMMENDED PRACTICEJ1939-14 DEC2016Issued 2011-10Revised 2016-12Superseding

5、 J1939-14 OCT2011Physical Layer, 500 KbpsRATIONALEScope is revised to exclude the use of Flexible Data Rate Frame Format messages as described in ISO 11898-1:2015.FOREWORDThe set of SAE J1939 Recommended Practice documents define a high speed ISO 11898 CAN protocol based communications network that

6、can support real-time closed loop control functions, simple information exchanges, and diagnostic data exchanges between Electronic Control Units (ECUs) physically distributed throughout the vehicle.The SAE J1939 communications network is developed for use in heavy-duty environments and suitable for

7、 use in horizontally integrated vehicle industries. The physical layer aspects of SAE J1939 reflect its design goal for use in heavy-duty environments. Horizontally integrated vehicles involve the integration of different combinations of loose package components, such as engines and transmissions, w

8、hich are sourced from many different component suppliers. The SAE J1939 common communication architecture strives to offer an open interconnect system that allows the ECUs associated with different component manufacturers to communicate with each other.The SAE J1939 communications network is intende

9、d for light-duty, medium-duty, and heavy-duty vehicles used on-road or off-road, and for appropriate stationary applications which use vehicle derived components (e.g. generator sets). Vehicles of interest include, but are not limited to, on-highway and off-highway trucks and their trailers, constru

10、ction equipment, and agricultural equipment and implements.This set of SAE Recommended Practices has been developed by the SAE Truck and Bus Control and Communications Network Committee of the SAE Truck and Bus Electrical and Electronics Steering Committee. The SAE J1939 communications network is de

11、fined using a collection of individual SAE J1939 documents based upon the layers of the Open System Interconnect (OSI) model for computer communications architecture. These SAE J1939 documents are intended as a guide toward standard practice and are subject to change to keep pace with experience and

12、 technical advances.SAE INTERNATIONAL J1939-14 DEC2016 Page 2 of 13TABLE OF CONTENTS1. SCOPE. 21.1 Purpose 32. REFERENCES. 32.1 Applicable Documents . 32.1.1 SAE Publications 32.1.2 ISO Publications. 33. DEFINITIONS 34. NETWORK. 54.1 WIRE 54.1.1 Type . 54.1.2 Environmental Requirements. 54.1.3 Cable

13、 Properties 54.1.4 Color. 54.2 Topology 64.2.1 Stubs 64.2.2 Distance Between Nodes and Number of Nodes 64.3 Connectors. 74.3.1 Terminators 74.3.2 ECU Type 1 and Type II markings. 74.3.3 Diagnostic Connection . 75. ECU TRANSCEIVER REQUIREMENTS. 85.1 Impedance . 85.2 Transmitter . 85.2.1 Voltage Level

14、s 85.2.2 Symmetry . 85.3 Receiver . 95.4 Time Delay . 95.5 Protection . 96. BIT TIMING 106.1 Oscillator Tolerance . 106.2 Number of Time Quanta (Tq). 106.3 Synchronization Jump Width (SJW) 106.4 Number of Samples . 106.5 Sample Point 106.6 Examples . 107. NOTES. 117.1 Revision Indicator. 11APPENDIX

15、A EXAMPLE CIRCUITS 121. SCOPEThis document defines a physical layer having a higher bandwidth capacity than other physical layers defined for SAE J1939. Newer transceiver technologies are utilized to minimize EMI.CAN controllers are now available which support the Flexible Data Rate Frame Format. Th

16、ese controllers, when used on SAE J1939-14 networks, must be restricted to use only the Classical Frame Format compliant to ISO 11898-1:2015.This SAE Recommended Practice is intended for light- and heavy-duty vehicles on- or off-road as well as appropriate stationary applications which use vehicle d

17、erived components (e.g., generator sets). Vehicles of interest include but are not limited to: on- and off-highway trucks and their trailers; construction equipment; and agricultural equipment and implements.SAE INTERNATIONAL J1939-14 DEC2016 Page 3 of 131.1 PurposeImplementing a robust CAN network

18、involves many tradeoffs affecting both the network layout and ECU design. This document presents a standard by which ECUs, tools, and vehicle networks from different sources may be compatible. The document is intended to stand alone, yet borrows from the many existing standards and papers for its me

19、thodology.2. REFERENCES2.1 Applicable DocumentsThe following publications form a part of this specification to the extent specified herein. Unless otherwise indicated, the latest issue of SAE publications shall apply.2.1.1 SAE PublicationsAvailable from SAE International, 400 Commonwealth Drive, War

20、rendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or +1 724-776-4970 (outside USA), www.sae.org.SAE J1128 Low Voltage Primary CableSAE J1939-11 Physical Layer, 250 Kbps, Twisted Shielded PairSAE J1939-13 Off-Board Diagnostic ConnectorSAE J1939-15 Physical Layer, 250 Kbps, Un-Shielded

21、 Twisted Pair (UTP)SAE J1939-16 Automatic Baud Rate Detection SAE J2030 Heavy-Duty Electrical Connector Performance Standard2.1.2 ISO PublicationsCopies of these documents are available online at http:/webstore.ansi.org/ISO 11898-1:2015 Road vehicles - Controller area network (CAN) - Part 1: Data li

22、nk layer and physical signallingISO 11898-2:2016 Road vehicles - Controller area network (CAN) - Part 2: High-speed medium access unit.3. DEFINITIONSMany of the definitions in this document can also be found in J1939-11, and in some cases paraphrase definitions given in ISO 11898-2:2016.3.1 TIME QUA

23、NTA (TQ)The interval of the CAN system clock. An integer multiple of the system clock period, the smallest division of a bit time used by the CAN controller.3.2 BIT TIMEThe nominal bit time, tB, (duration of one bit in the arbitration phase) and data bit time, tD, (duration of one bit in the data ph

24、ase) for this document is 2 s corresponding to 500 kbps. Bus management functions executed within this bit time, such as ECU synchronization behavior, network transmission delay compensation, and sample point positioning, are defined by the programmable bit timing logic of the CAN protocol IC (Integ

25、rated Circuit).3.3 BAUD RATE PRESCALER (BRP)A parameter of the CAN controller that determines a divisor by which the system clock frequency is reduced to produce the CAN system clock.SAE INTERNATIONAL J1939-14 DEC2016 Page 4 of 133.4 SYNCHRONIZATION JUMP WIDTH (SJW)The maximum interval by which PHAS

26、E_SEG1 and PHASE_SEG2 may be adjusted.3.5 SYNC_SEGThe first 1 Tq portion of a bit time. An edge is expected within this bit segment.3.6 PROP_SEGA part of the bit time used to compensate for the physical delay times within the network.3.7 PHASE_SEG1The first segment of the bit time used to compensate

27、 for phase errors. May be lengthened by an amount less than or equal to SJW.3.8 PHASE_SEG2The second segment of the bit time used to compensate for phase errors. May be shortened by an amount less than or equal to SJW.3.9 TSEG1Combination of the PROP_SEG and PHASE_SEG1.3.10 TSEG2Same as PHASE_SEG2.3

28、.11 SAMPLE POINTThe point of time at which the bus level is read and interpreted as the value of that respective bit. Its location is at the end of PHASE_SEG1.3.12 DIFFERENTIAL VOTAGEThe voltages of CAN_H and CAN_L relative to ground of each individual ECU are denoted by VCAN_H andVCAN_L. The differ

29、ential voltage between VCAN_H and VCAN_L is defined by Equation 1:L_CANH_CANdiff VVV (Eq. 1)3.13 COMMON-MODE BUS VOLTAGE RANGEThe common-mode bus voltage is defined as the boundary voltage levels of CAN_H and CAN_L, measured with respect to the individual ground of each ECU, for which proper operati

30、on is guaranteed when all ECUs are connected to the bus line.3.14 INTERNAL RESISTANCEThe internal resistance, RIN, of an ECU is defined as the resistance between CAN_H (or CAN_L) and ground during the recessive state, with the ECU disconnected from the bus line.3.15 DIFFERENTIAL INTERNAL RESISTANCET

31、he differential internal resistance, RDIFF, is defined as the resistance between CAN_H and CAN_L during the recessive state, with the ECU disconnected from the bus line.SAE INTERNATIONAL J1939-14 DEC2016 Page 5 of 133.16 INTERNAL CAPACITANCEThe internal capacitance, CIN, of an ECU is defined as the

32、capacitance between CAN_H (or CAN_L) and ground during the recessive state, with the ECU disconnected from the bus line3.17 DIFFERENTIAL INTERNAL CAPACITANCEThe differential internal capacitance, CDIFF, of an ECU is defined as the capacitance between CAN_H and CAN_L during the recessive state, with

33、the ECU disconnected from the bus line.3.18 TYPE I ECUAn ECU that does not contain bus line termination.3.19 TYPE II ECUAn ECU that includes a bus line termination resistor or split termination. Such an ECU, if used, shall be located at one or both ends of a network and shall be marked as specified

34、in Section 4.3.2.4. NETWORKPhysical wiring specifications for harness designers and wiring system manufacturers.4.1 WIRECables meeting SAE J1939-11 or SAE J1939-15 are acceptable.4.1.1 TypeShielded or unshielded twisted pair wire may be used. Maintaining the twist to the greatest extent possible is

35、critical to meeting radiated emissions and susceptibility requirements. The twist requirements are specified in table 1 and are controlled by the lay length specification Jacketed cable is recommended to maintain consistent twisting and impedance. When using shielded cable, it is especially importan

36、t to observe the minimum bend radius requirement to avoid internal damage to the shield.When shielded cable is used, shield should be terminated as described in SAE J1939-11. For mixed shielded/unshielded configurations, follow recommendations in SAE J1939-15.4.1.2 Environmental RequirementsCable sh

37、ould meet the environmental requirements of the application. Typically, cables for heavy truck applications will need to meet SAE J1128 requirements for SXL or GXL type wire.4.1.3 Cable PropertiesTable 1 - Cable propertiesParameter Symbol Min Nom Max UnitImpedance Z 108 120 132 :Specific Resistance

38、rb 0 25 50 m:/mSpecific Line Delay tp 5.0 5.5 ns/mLay Length 20 25 38 mmCable Bend Radius r 4x dia. of cable mm4.1.4 ColorThe CAN_H conductor should be yellow and the CAN_L conductor should be green.SAE INTERNATIONAL J1939-14 DEC2016 Page 6 of 134.2 TopologyThe network shall have a linear topology c

39、onsisting of a backbone and multiple stubs by which ECUs are connected. Stubs may have zero length, provided that the backbone is properly terminated at the ends.4.2.1 StubsThe maximum length of a stub shall be 1.67 meters. A stub may be left unconnected to an ECU, but this stub will count towards t

40、he maximum number of nodes on the network. It is recommended that the length of stubs be varied to reduce the likelihood of coincident reflections.4.2.2 Distance Between Nodes and Number of NodesThe minimum distance between stubs should be 30 cm to minimize impedance mismatch on the backbone due to

41、accumulated capacitive load.The maximum distance between the farthest nodes (including stubs) on the network is allowed to vary according to the number of nodes on the network. Each node connected to the network adds capacitive load and effectively slows the rate of signal propagation on the network

42、. The maximum number of nodes is 30. Table 2 Node count vs. distanceNumber of Nodes Maximum Distance Between Nodes2 56.4 m3 55.5 m4 54.7 m5 54.0 m6 53.3 m7 52.5 m8 51.8 m9 51.1 m10 50.5 m11 49.8 m12 49.2 m13 48.5 m14 48.0 m15 47.4 m16 46.8 m17 46.3 m18 45.7 m19 45.2 m20 44.6 m21 44.1 m22 43.6 m23 43

43、.2 m24 42.6 m25 42.2 m26 41.7 m27 41.3 m28 40.5 m29 40.1 m30 40.0 mSAE INTERNATIONAL J1939-14 DEC2016 Page 7 of 134.3 ConnectorsEither splices or connectors may be used to connect stubs to the backbone. Splice methodologies and connectors should be chosen to minimize the untwisted length of wire. Co

44、nnectors should meet performance specifications of SAE J2030 for “signal level circuits”. Circuits of this type are defined in SAE J2030 as a circuit in which open circuit voltage is typically less than 5 V and current is typically less than 0.05 A.4.3.1 TerminatorsEach of the two endpoints of the b

45、ackbone must be terminated across the CAN_H and CAN_L conductors with a resistance equal to the characteristic impedance of the cable. These terminators suppress signal reflections. Also, without these resistors, the proper differential voltage is not produced between the conductors.4.3.1.1 Terminat

46、ion resistanceTermination resistance may be included within an ECU connected at the end of the network. If so, it shall be clearly identified in the device documentation or on the device itself.Table 3 - Terminating resistor parametersParameter Symbol Min Nom Max UnitResistance RL 110 120 130 :4.3.1

47、.2 Split termination of backboneOne or both ends of the backbone may be terminated with split termination in which RL is divided into two well matching resistors. In order to achieve good electro-magnetic emission performance, it is recommended not to exceed +/- 1 % tolerance between the two identic

48、al resistors of the split termination locally. Reference ISO 11898-2:2016.The center tap between the resistors should be connected to ground through a 4.7 nF capacitor, CL.4.3.1.3 Node terminationImpedance characteristics of the CAN connections at the ECU specified within this document preclude the

49、use of termination at the node. Providing termination at nodes (excepting those that terminate the backbone) would reduce the number of nodes capable of being supported on the network.4.3.2 ECU Type 1 and Type II markingsAn ECU that does not contain an internal Load Resistor (RL) shall be designated as a Type I ECU and does not require a marking. An ECU that contains an internal RL shall be designated as a Type II ECU. The T