SAE-J1850-2001.pdf

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 therefrom, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions. TO PLACE A DOCUMENT ORDER: +1 (724) 776-4970 FAX: +1 (724) 776-0790 SAE WEB ADDRESS http:/www.sae.org Copyright 2001 Society of Automotive Engineers, Inc. All rights reserved.Printed in U.S.A. SURFACE VEHICLE 400 Commonwealth Drive, Warrendale, PA 15096-0001 STANDARD J1850 REV. MAY2001 Issued1988-11 Revised2001-05 Superseding J1850 MAR1998 Class B Data Communications Network Interface TABLE OF CONTENTS 1.Scope 4 1.1Objectives.4 2.References. 4 2.1Applicable Documents4 2.1.1SAE Publications 4 2.1.2CISPR Publication 5 2.1.3ISO Publications.5 2.2Related Publication 5 2.2.1SAE Publication 5 3.Definitions.5 4.Abbreviations/Acronyms 6 5.Description of the Architecture . 7 5.1General.7 5.2Network Topology 7 5.2.1Data Bus Topology. 7 5.2.2Data Bus Control 7 5.3References to the OSI Model. 7 5.3.1Application Layer 8 5.3.2Data Link Layer 9 5.3.3Physical Layer 9 5.4Network Implementation. 9 6.Application Layer Details10 6.1Normal Vehicle Operation (Down the Road) Messages.10 6.2Diagnostic Messages . 10 6.2.1Diagnostic Parametric Data 10 6.2.2Diagnostic Malfunction Codes 11 6.3Frame Filtering . 11 Copyright SAE International Provided by IHS under license with SAE Not for ResaleNo reproduction or networking permitted without license from IHS -,- SAE J1850 Revised MAY2001 -2- 7.Data Link Layer Details.11 7.1Addressing Strategy .11 7.1.1Physical Addressing .11 7.1.2Functional Addressing 11 7.2Network Access and Data Synchronization11 7.2.1Full Message Buffering.11 7.2.2Byte Buffering .11 7.3Network Elements and Structure 12 7.3.1Frame Elements .12 7.3.2Bit Ordering.12 7.3.3Maximum Frame Length.12 7.3.4Function of SOF, EOD, EOF, IFS, NB, and BRK .12 7.3.4.1Start of Frame (SOF) 12 7.3.4.2End of Data (EOD)12 7.3.4.3End of Frame (EOF) .12 7.3.4.4Inter-Frame Separation (IFS)12 7.3.4.5Normalization Bit (NB) 13 7.3.4.6Break (BRK)13 7.3.5Idle Bus (Idle)13 7.3.6Data Byte(s)13 7.3.7In-Frame Response (IFR).13 7.3.7.1Normalization Bit.14 7.4Error Detection14 7.4.1Cyclic Redundancy Check (CRC).15 7.4.2Frame/Message Length17 7.4.3Out-of-Range 17 7.4.4Concept of Valid/Invalid Bit/Symbol Detection17 7.4.4.1Invalid Bit Detection 17 7.4.4.2Invalid Frame Structure Detection17 7.5Error Response.17 7.5.1Transmit17 7.5.2Receive .17 8.Physical Layer Details 17 8.1Physical Layer Media17 8.1.1Single Wire .17 8.1.2Dual Wires 17 8.1.3Routing .18 8.2Unit Load Specifications .18 8.3Maximum Number of Nodes .18 8.4Maximum Network Length18 8.4.1On-Vehicle/Off-Vehicle .18 8.5Media Characteristics .18 8.6Data Bit/Symbol Definition/Detection18 8.6.1Pulse Width Modulation (PWM) 18 8.6.1.1The One “1” and Zero “0” Bits.19 8.6.1.2Start of Frame (SOF) 19 8.6.1.3End of Data (EOD)20 8.6.1.4End of Frame (EOF) .20 8.6.1.5Inter-Frame Separation (IFS)21 8.6.1.6Break (BRK)21 8.6.1.7Idle Bus (Idle)21 8.6.1.8PWM Symbol Timing Requirements.22 Copyright SAE International Provided by IHS under license with SAE Not for ResaleNo reproduction or networking permitted without license from IHS -,- SAE J1850 Revised MAY2001 -3- 8.6.2Variable Pulse Width Modulation22 8.6.2.1The One “1” and Zero “0” Bits.22 8.6.2.2Start Of Frame (SOF) .22 8.6.2.3End Of Data (EOD).23 8.6.2.4End of Frame (EOF) .23 8.6.2.5In-Frame Response Byte(s)/Normalization Bit23 8.6.2.6Inter-Frame Separation (IFS)24 8.6.2.7Break (BRK)24 8.6.2.8Idle Bus (Idle)24 8.6.2.9VPW Symbol Timing Requirements25 8.7Contention/Arbitration/Priority.25 8.7.1Contention Detection25 8.7.2Bit-by-Bit Arbitration26 8.7.3Arbitration Area.26 8.7.4Frame Priority .26 8.8Node Wake-Up Via Physical Layer.27 8.8.1Network Media28 8.8.1.1Unbiased Network 28 8.8.1.2Biased Network.28 8.8.2Individual Nodes.28 8.8.2.1Unpowered Node28 8.8.2.2Sleeping Node28 8.8.2.3Awake/Operational .28 8.9Physical Layer Fault Considerations 28 8.9.1Required Fault Tolerant Modes 28 8.9.2Optional Fault Tolerant Modes .29 8.10EMC Requirements 29 9.Parameters .30 9.1Application Layer30 9.2Data Link Layer.30 9.2.1Pulse Width Modulation (PWM) at 41.6 Kbps.30 9.2.2Variable Pulse Width (VPW) at 10.4 Kbps30 9.3Physical Layer 30 9.3.1General Network Requirements .30 9.3.2Pulse Width Modulation (PWM) 30 9.3.2.1PWM Timing Requirements30 9.3.2.2PWM DC Parameters .32 9.3.3Variable Pulse Width Modulation (VPW)33 9.3.3.1VPW Timing Requirements 33 9.3.3.2VPW DC Parameters33 10.Notes 34 10.1Marginal Indicia.34 Appendix A Checklist Of Application-Specific Features .35 Appendix B I/O EMC Test Plan 37 Appendix C VPW Waveform Analysis40 Appendix D PWM Waveform Analysis .44 Copyright SAE International Provided by IHS under license with SAE Not for ResaleNo reproduction or networking permitted without license from IHS -,- SAE J1850 Revised MAY2001 -4- 1.ScopeThis SAE Standard establishes the requirements for a Class B Data Communication Network Interface applicable to all On- and Off-Road Land-Based Vehicles. It defines a minimum set of data communication requirements such that the resulting network is cost effective for simple applications and flexible enough to use in complex applications. Taken in total, the requirements contained in this document specify a data communications network that satisfies the needs of automotive manufacturers. This specification describes two specific implementations of the network, based on media/Physical Layer differences. One Physical Layer is optimized for a data rate of 10.4 Kbps while the other Physical Layer is optimized for a data rate of 41.6 Kbps (see Appendix A for a checklist of application-specific features). The Physical Layer parameters are specified as they would be detected on the network media, not within any particular module or integrated circuit implementation. Although devices may be constructed that can be configured to operate in either of the two primary implementations defined herein, it is expected that most manufacturers will focus specifically on either the 10.4 Kbps implementation or the 41.6 Kbps implementation depending on their specific application and corporate philosophy toward network usage. However, low-volume users of network-interface devices are expected to find it more effective to use a generic interface capable of handling either of the primary implementations specified in this document. This SAE document is under the control and maintenance of the Vehicle Networks for Multiplexing and Data Communications (Multiplex) Committee. This committee will periodically review and update this document as needs dictate. 1.1ObjectivesThis document constitutes the requirements for a vehicle-data communications network. These requirements are related to the lowest two layers of the ISO Open System Interconnect (OSI) model (Ref. ISO 7498). These layers are the Data Link Layer and the Physical Layer. This network has been described using the ISO conventions in ISO/TC 22/SC 3/WG1 N429 E, dated October, 1990. Both documents are intended to describe the same network requirements but using different descriptive styles. If any technical differences are identified, the very latest revision of these documents should be used. This document has been submitted as an American National Standard. As such, its format is somewhat different from the formal ISO description in that descriptions have been expanded, but are in no way less precise. A more textual format has been adopted herein to allow explanations to be included. The vehicle application for this class of data communication (Class B) network is defined (Reference SAE J1213 APR88) to allow the sharing of vehicle parametric information. Also per the definition, this Class B network shall be capable of performing Class A functions. 2.References 2.1Applicable PublicationsThe following publications form a part of this specification to the extent specified herein. The latest issue of SAE publications shall apply. 2.1.1SAE PUBLICATIONSAvailable from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001. SAE J1113Electromagnetic Susceptibility Measurements Procedures for Vehicle Components SAE J1211ARecommended Environmental Procedure for Electronic Equipment Design SAE J1213/1Glossary of Vehicle Networks for Multiplexing and Data Communications SAE J1547Electromagnetic Susceptibility Measurement Procedures for Common Mode Injection SAEJ1879General Qualification and Production Acceptance Criteria for Integrated Circuits in Automo- tive Applications SAE J1962Diagnostic Connector SAE J1979E/E Diagnostic Test Modes SAE J2012Diagnostic Codes/Messages Copyright SAE International Provided by IHS under license with SAE Not for ResaleNo reproduction or networking permitted without license from IHS -,- SAE J1850 Revised MAY2001 -5- SAE J2178Class B Data Communication Network Messages SAEJ2178/1Class B Data Communication Network Messages: Detailed Header Formats and Physical Address Assignment SAE J2190Enhanced E/E Diagnostic Test Modes 2.1.2CISPR PUBLICATIONAvailable from Kristi Hansen, SAE, Troy Office, 3001 West Big Beaver Road, Suite 320, Troy, MI 48084-3174. CISPR/D/WG2 (Secretariat) 19 Sept 1989Radiated Emissions Antenna and Probe Test 2.1.3ISO PUBLICATIONSAvailable from ANSI, 11 West 42nd Street, New York, NY 10036-8002. ISO/TC22/SC3/WG1 N429E OCT90Road vehiclesSerial data communication for automotive applica- tions, low speed (125 Kbps and below) ISO 7498Data processing systemsOpen systems interconnectionStandard reference model ISO7637/3Road vehiclesElectrical disturbance by conduction and couplingPart 3: Passenger cars and light commercial vehicles with nominal 12 V supply voltage and commercial vehicles with 24 V supply voltageElectrical transient transmission by capacitive and inductive coupling via lines other than supply lines 2.2Related PublicationsThe following publication is provided for information purposes only and is not a required part of this document. 2.2.1SAE PUBLICATIONAvailable from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001. SAE J1930Electrical/Electronic Systems Diagnostic Terms, Definitions, Abbreviations, see 7.1), the criteria for these filtering operations may include multiple byte comparisons occurring over the first several frame bytes. Regardless of the exact technique used for frame filtering, the objective is to reduce the software and processing burden associated with network operations by limiting the number of received frames to just those necessary for any given node. 7.Data Link Layer DetailsThis section defines the requirements on the following Data Link Layer attributes: a.Addressing Strategy b.Network Access and Data Synchronization c.Frame Elements and Structure d.Error Detection e.Error Response 7.1Addressing StrategyTwo types of addressing strategies are defined and can co-exist on this network. The two strategies serve different types of tasks and the flexibility to use both types on the same network provides a major benefit. 7.1.1PHYSICAL ADDRESSINGFrames are exchanged only between two devices based on their “Physical” address within the network. Each node must be assigned a unique physical address within the network. This type of addressing strategy is used when the communications involve specific nodes and not the others that may be on the network. Diagnostic access would be one case where identification of a specific module is important. 7.1.2FUNCTIONAL ADDRESSINGFrames can be transmitted between many devices based on the function of that frame on the network. Each node is assigned the set of functions that it cares about, either as transmitter or receiver, and can be located anywhere in the network. This type of addressing strategy is used when the physical location of the function is not important but could move around from one module to another. In the case of functional addressing, the function of the message is important and not the physical addresses of the nodes. 7.2Network Access and Data SynchronizationThe network interface shall implement a multiple access arbitration-based protocol using nondestructive bit-by-bit arbitration to transparently resolve simultaneous access to the bus. Network access is allowed after detection of an idle bus. The definition of an idle bus is contained in 8.6.1.7. Since a discrete clock wire is not used with this network, node synchronization can be derived from bit/symbol transitions on the bus. 7.2.1FULL MESSAGE BUFFERINGOne or more messages exist in their entirety in the interface device. This approach reduces software burden at the expense of hardware costs. Message filtering (or screening) is possible in such a device which reduces software burden even further. 7.2.2BYTE BUFFERINGEach byte of a received message (or transmit message) is stored individually in the interface device. The controlling device is responsible for the timely servicing of the interface device to keep up with frame traffic. Copyright SAE International Provided by IHS under license with SAE Not for ResaleNo reproduction or networking permitted without license from IHS -,- SAE J1850 Revised MAY2001 -12- 7.3Network Elements and StructureThe general format is: idle, SOF, DATA_0, ., DATA_N, CRC, EOD, NB, IFR_1, ., IFR_N, EOF, IFS, idle: The preceding acronyms are defined as follows: idle:Idle Bus (occurs before SOF and after IFS) SOF:Start of Frame DATA: Data bytes (each 8 bits long) EOD:End of Data (only when IFR is used) CRC:CRC Error Detection Byte (may occur in IFR as well) NB:Normalization Bit (10.4 Kbps only) IFR:In-Frame Response Byte(s) EOF:End of Frame IFS:Inter-Frame Separation NOTEBreak (BRK) can occur (be sent) on a network at any time. 7.3.1FRAME ELEMENTSThe frame elements other than the symbols SOF, EOD, NB, EOF, IFS, and BRK will be byte oriented and must end on byte boundaries. Each byte will be 8 bits in length. 7.3.2BIT ORDERINGThe first bit of each byte transmitted on the network shall be the most significant bit (i.e., MSB first). 7.3.3MAXIMUM FRAME LENGTHThe maximum number of continuous bit times that a single node is able to control the bus shall not exceed the value specified in 9.2. 7.3.4FUNCTION OF SOF, EOD, EOF, IFS, NB, AND BRKIn addition to actual data bytes (i.e., data, CRC, IFR) frame delimiter symbols are defined to allow the data bus to function properly in a multitude of different applications. An overview of these symbols is provided here. Detailed timing requirements on each symbol can be found in 9.3. 7.3.4.1Start of Frame (SOF)The SOF mark is used to u