Downloaded from SAE International by Joshua Jaffe, Thursday, December 01, 2016
`
`400 Commonwealth Drive, Warrendale, PA 15096-0001
`
`SURFACE
`VEHICLE
`STANDARD
`
`J1850
`
`REV.
`MAY2001
`
`Issued
`Revised
`
`1988-11
`2001-05
`
`Superseding J1850 MAR1998
`
`Class B Data Communications Network Interface
`
`TABLE OF CONTENTS
`
`Scope ...................................................................................................................................................... 4
`Objectives................................................................................................................................................. 4
`
`References ............................................................................................................................................... 4
`Applicable Documents.............................................................................................................................. 4
`SAE Publications...................................................................................................................................... 4
`CISPR Publication .................................................................................................................................... 5
`ISO Publications ....................................................................................................................................... 5
`Related Publication .................................................................................................................................. 5
`SAE Publication ........................................................................................................................................ 5
`
`Definitions................................................................................................................................................. 5
`
`Abbreviations/Acronyms.......................................................................................................................... 6
`
`Description of the Architecture ................................................................................................................. 7
`General..................................................................................................................................................... 7
`Network Topology .................................................................................................................................... 7
`Data Bus Topology................................................................................................................................... 7
`Data Bus Control...................................................................................................................................... 7
`References to the OSI Model ................................................................................................................... 7
`Application Layer ...................................................................................................................................... 8
`Data Link Layer ........................................................................................................................................ 9
`Physical Layer .......................................................................................................................................... 9
`Network Implementation ........................................................................................................................... 9
`
`Application Layer Details ........................................................................................................................ 10
`Normal Vehicle Operation (Down the Road) Messages ......................................................................... 10
`Diagnostic Messages ............................................................................................................................. 10
`Diagnostic Parametric Data.................................................................................................................... 10
`Diagnostic Malfunction Codes................................................................................................................ 11
`Frame Filtering ....................................................................................................................................... 11
`
`1.
`1.1
`
`2.
`2.1
`2.1.1
`2.1.2
`2.1.3
`2.2
`2.2.1
`
`3.
`
`4.
`
`5.
`5.1
`5.2
`5.2.1
`5.2.2
`5.3
`5.3.1
`5.3.2
`5.3.3
`5.4
`
`6.
`6.1
`6.2
`6.2.1
`6.2.2
`6.3
`
`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.
`
`Page 1 of 48
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`SAE J1850 Revised MAY2001
`
`7.
`7.1
`7.1.1
`7.1.2
`7.2
`7.2.1
`7.2.2
`7.3
`7.3.1
`7.3.2
`7.3.3
`7.3.4
`7.3.4.1
`7.3.4.2
`7.3.4.3
`7.3.4.4
`7.3.4.5
`7.3.4.6
`7.3.5
`7.3.6
`7.3.7
`7.3.7.1
`7.4
`7.4.1
`7.4.2
`7.4.3
`7.4.4
`7.4.4.1
`7.4.4.2
`7.5
`7.5.1
`7.5.2
`
`8.
`8.1
`8.1.1
`8.1.2
`8.1.3
`8.2
`8.3
`8.4
`8.4.1
`8.5
`8.6
`8.6.1
`8.6.1.1
`8.6.1.2
`8.6.1.3
`8.6.1.4
`8.6.1.5
`8.6.1.6
`8.6.1.7
`8.6.1.8
`
`Data Link Layer Details........................................................................................................................... 11
`Addressing Strategy ...............................................................................................................................11
`Physical Addressing ...............................................................................................................................11
`Functional Addressing ............................................................................................................................11
`Network Access and Data Synchronization ............................................................................................ 11
`Full Message Buffering........................................................................................................................... 11
`Byte Buffering ......................................................................................................................................... 11
`Network Elements and Structure ............................................................................................................ 12
`Frame Elements .....................................................................................................................................12
`Bit Ordering ............................................................................................................................................. 12
`Maximum Frame Length......................................................................................................................... 12
`Function of SOF, EOD, EOF, IFS, NB, and BRK ...................................................................................12
`Start of Frame (SOF) .............................................................................................................................. 12
`End of Data (EOD) ..................................................................................................................................12
`End of Frame (EOF) ...............................................................................................................................12
`Inter-Frame Separation (IFS).................................................................................................................. 12
`Normalization Bit (NB) ............................................................................................................................13
`Break (BRK)............................................................................................................................................13
`Idle Bus (Idle).......................................................................................................................................... 13
`Data Byte(s) ............................................................................................................................................13
`In-Frame Response (IFR)....................................................................................................................... 13
`Normalization Bit.....................................................................................................................................14
`Error Detection........................................................................................................................................ 14
`Cyclic Redundancy Check (CRC) ...........................................................................................................15
`Frame/Message Length.......................................................................................................................... 17
`Out-of-Range .......................................................................................................................................... 17
`Concept of Valid/Invalid Bit/Symbol Detection........................................................................................ 17
`Invalid Bit Detection ................................................................................................................................ 17
`Invalid Frame Structure Detection .......................................................................................................... 17
`Error Response....................................................................................................................................... 17
`Transmit.................................................................................................................................................. 17
`Receive ...................................................................................................................................................17
`
`Physical Layer Details ............................................................................................................................17
`Physical Layer Media.............................................................................................................................. 17
`Single Wire ............................................................................................................................................. 17
`Dual Wires .............................................................................................................................................. 17
`Routing ...................................................................................................................................................18
`Unit Load Specifications ......................................................................................................................... 18
`Maximum Number of Nodes ................................................................................................................... 18
`Maximum Network Length ...................................................................................................................... 18
`On-Vehicle/Off-Vehicle ........................................................................................................................... 18
`Media Characteristics ............................................................................................................................. 18
`Data Bit/Symbol Definition/Detection ...................................................................................................... 18
`Pulse Width Modulation (PWM) ..............................................................................................................18
`The One “1” and Zero “0” Bits................................................................................................................. 19
`Start of Frame (SOF) .............................................................................................................................. 19
`End of Data (EOD) ..................................................................................................................................20
`End of Frame (EOF) ...............................................................................................................................20
`Inter-Frame Separation (IFS).................................................................................................................. 21
`Break (BRK)............................................................................................................................................21
`Idle Bus (Idle).......................................................................................................................................... 21
`PWM Symbol Timing Requirements .......................................................................................................22
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`8.6.2
`8.6.2.1
`8.6.2.2
`8.6.2.3
`8.6.2.4
`8.6.2.5
`8.6.2.6
`8.6.2.7
`8.6.2.8
`8.6.2.9
`8.7
`8.7.1
`8.7.2
`8.7.3
`8.7.4
`8.8
`8.8.1
`8.8.1.1
`8.8.1.2
`8.8.2
`8.8.2.1
`8.8.2.2
`8.8.2.3
`8.9
`8.9.1
`8.9.2
`8.10
`
`9.
`9.1
`9.2
`9.2.1
`9.2.2
`9.3
`9.3.1
`9.3.2
`9.3.2.1
`9.3.2.2
`9.3.3
`9.3.3.1
`9.3.3.2
`
`10.
`10.1
`
`Variable Pulse Width Modulation............................................................................................................ 22
`The One “1” and Zero “0” Bits................................................................................................................. 22
`Start Of Frame (SOF) ............................................................................................................................. 22
`End Of Data (EOD)................................................................................................................................. 23
`End of Frame (EOF) ...............................................................................................................................23
`In-Frame Response Byte(s)/Normalization Bit........................................................................................ 23
`Inter-Frame Separation (IFS).................................................................................................................. 24
`Break (BRK)............................................................................................................................................24
`Idle Bus (Idle).......................................................................................................................................... 24
`VPW Symbol Timing Requirements........................................................................................................ 25
`Contention/Arbitration/Priority................................................................................................................. 25
`Contention Detection .............................................................................................................................. 25
`Bit-by-Bit Arbitration................................................................................................................................ 26
`Arbitration Area ....................................................................................................................................... 26
`Frame Priority ......................................................................................................................................... 26
`Node Wake-Up Via Physical Layer......................................................................................................... 27
`Network Media ........................................................................................................................................ 28
`Unbiased Network ..................................................................................................................................28
`Biased Network ....................................................................................................................................... 28
`Individual Nodes .....................................................................................................................................28
`Unpowered Node .................................................................................................................................... 28
`Sleeping Node ........................................................................................................................................ 28
`Awake/Operational ................................................................................................................................. 28
`Physical Layer Fault Considerations ...................................................................................................... 28
`Required Fault Tolerant Modes ..............................................................................................................28
`Optional Fault Tolerant Modes ............................................................................................................... 29
`EMC Requirements ................................................................................................................................ 29
`
`Parameters ............................................................................................................................................. 30
`Application Layer .................................................................................................................................... 30
`Data Link Layer....................................................................................................................................... 30
`Pulse Width Modulation (PWM) at 41.6 Kbps......................................................................................... 30
`Variable Pulse Width (VPW) at 10.4 Kbps .............................................................................................. 30
`Physical Layer ........................................................................................................................................ 30
`General Network Requirements ............................................................................................................. 30
`Pulse Width Modulation (PWM) ..............................................................................................................30
`PWM Timing Requirements.................................................................................................................... 30
`PWM DC Parameters ............................................................................................................................. 32
`Variable Pulse Width Modulation (VPW) ................................................................................................ 33
`VPW Timing Requirements .................................................................................................................... 33
`VPW DC Parameters .............................................................................................................................. 33
`
`Notes ......................................................................................................................................................34
`Marginal Indicia....................................................................................................................................... 34
`
`Appendix A Checklist Of Application-Specific Features .............................................................................................35
`Appendix B I/O EMC Test Plan ..................................................................................................................................37
`Appendix C VPW Waveform Analysis ........................................................................................................................40
`Appendix D PWM Waveform Analysis ....................................................................................................................... 44
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`SAE J1850 Revised MAY2001
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`1.
`
`Scope—This 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.
`
`1.1 Objectives—This 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
`
`2.1 Applicable Publications—The following publications form a part of this specification to the extent specified
`herein. The latest issue of SAE publications shall apply.
`
`2.1.1
`
`SAE PUBLIC ATIO NS—Available from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001.
`
`SAE J1113—Electromagnetic Susceptibility Measurements Procedures for Vehicle Components
`SAE J1211A—Recommended Environmental Procedure for Electronic Equipment Design
`SAE J1213/1—Glossary of Vehicle Networks for Multiplexing and Data Communications
`SAE J1547—Electromagnetic Susceptibility Measurement Procedures for Common Mode Injection
`SAEJ1879—General Qualification and Production Acceptance Criteria for Integrated Circuits in Automo-
`tive Applications
`SAE J1962—Diagnostic Connector
`SAE J1979—E/E Diagnostic Test Modes
`SAE J2012—Diagnostic Codes/Messages
`
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`SAE J1850 Revised MAY2001
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`SAE J2178—Class B Data Communication Network Messages
`SAEJ2178/1—Class B Data Communication Network Messages: Detailed Header Formats and Physical
`Address Assignment
`SAE J2190—Enhanced E/E Diagnostic Test Modes
`
`2.1.2 CISPR PUBLIC ATIO N—Available from Kristi Hansen, SAE, Troy Office, 3001 West Big Beaver Road, Suite
`320, Troy, MI 48084-3174.
`
`CISPR/D/WG2 (Secretariat) 19 Sept 1989—Radiated Emissions Antenna and Probe Test
`
`2.1.3
`
`ISO P UBLIC AT IONS—Available from ANSI, 11 West 42nd Street, New York, NY 10036-8002.
`
`ISO/TC22/SC3/WG1 N429E OCT90—Road vehicles—Serial data communication for automotive applica-
`tions, low speed (125 Kbps and below)
`ISO 7498—Data processing systems—Open systems interconnection—Standard reference model
`ISO7637/3—Road vehicles—Electrical disturbance by conduction and coupling—Part 3: Passenger cars
`and light commercial vehicles with nominal 12 V supply voltage and commercial vehicles with 24 V
`supply voltage—Electrical transient transmission by capacitive and inductive coupling via lines other
`than supply lines
`
`2.2 Related Publications—The following publication is provided for information purposes only and is not a
`required part of this document.
`
`2.2.1
`
`SAE PUBLIC ATIO N—Available from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001.
`
`SAE J1930—Electrical/Electronic Systems Diagnostic Terms, Definitions, Abbreviations, & Acronyms
`
`3.
`
`Definitions
`
`3.1 Active State—The state of a bus wire which results when one or more nodes have “turned on” their physical
`layer circuitry. This is Voh volts for Bus + (PWM and VPW) and Vol volts for Bus – (PWM only). Refer to
`9.3.2.2 (PWM DC Parameters) and 9.3.3.2 (VPW DC Parameters) for the values of Voh and V ol. The active
`state voltage level is determined by the source voltage of the physical layer drive circuitry.
`
`3.2 Arbitration—The process of resolving which frame, or In-Frame Response data, continues to be transmitted
`when two or more nodes begin transmitting frames, or In-Frame Response data, simultaneously.
`
`3.3 Class A Data Communications—A system whereby vehicle wiring is reduced by the transmission and
`reception of multiple signals over the same signal bus between nodes that would have been accomplished by
`individual wires in a conventionally wired vehicle. The nodes used to accomplish multiplexed body wiring
`typically did not exist in the same or similar form in a conventionally wired vehicle.
`
`3.4 Class B Data Communications—A system whereby data (e.g., parametric data values) is transferred
`between nodes to eliminate redundant sensors and other system elements. The nodes in this form of a
`multiplex system typically already existed as stand-alone modules in a conventionally wired vehicle. A Class B
`network shall also be capable of performing Class A functions.
`
`3.5 Class C Data Communications—A system whereby high data rate signals typically associated with real-time
`control systems, such as engine controls and anti-lock brakes, are sent over the signal bus to facilitate
`distributed control and to further reduce vehicle wiring. A Class C network shall also be capable of performing
`Class A and Class B functions.
`
`3.6 Dominant Bit—A bit which wins arbitration when contending for the bus. For SAE J1850, a logic “0” is the
`dominant bit.
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`3.7 Dual Wire—Two wires that are routed adjacently throughout the network and can be either a twisted or a
`parallel pair of wires.
`
`3.8
`
`3.9
`
`Fault Tolerance—The ability of a system to survive a certain number of failures with allowance for possible
`downgraded performance while maintaining message transmission capability at the specified data rate.
`
`Frame—One complete transmission of information, which may or may not include an “in-frame response.” For
`this network, each frame contains one and only one message. A frame is delineated by the Start of Frame
`(SOF) and End of Frame (EOF) symbols.
`
`3.10 Functional Addressing—Labeling of messages based on their operation code or data content. See 7.1.2 for
`an example of the typical usage for functional addressing.
`
`3.11 Message—All of the data bytes contained in a frame. The message is what is left after the frame symbols
`have been removed from the frame. As such, the message is the sequence of bytes contained in the frame.
`
`3.12 Passive State—The state of a bus wire which results when all nodes have “turned off” their physical layer
`circuitry. This is Vol volts for Bus + (PWM and VPW) and Voh volts for Bus – (PWM only). Refer to 9.3.2.2
`(PWM DC Parameters) and 9.3.3.2 (VPW DC Parameters) for the values of Voh and Vol. The passive state
`voltage level is determined by the reference voltage of the bus wire termination resistor(s).
`
`3.13 Physical Addressing—Labeling of messages for the physical location of their source and/or destination(s).
`See 7.1.1 for an example of the typical usage for physical addressing.
`
`3.14 Pulse Width Modulation (PWM)— A data bit format, where the width of a pulse of constant voltage or current
`determines the value (typically one or zero) of the data transmitted.
`
`3.15 Recessive Bit—A bit which loses arbitration when contending for the bus with a dominant bit. For SAE J1850,
`a logic “1” is the recessive bit.
`
`3.16 Sleep-Mode—Node behavior in a low power consumption standby state waiting to be switched on by a frame
`or other activity. This is distinct from an off-mode where the node is disconnected from the power supply.
`
`3.17 Variable Pulse Width (VPW) Modulation—A method of using both the state of the bus and the width of the
`pulse to encode bit information. This encoding technique is used to reduce the number of bus transitions for a
`given bit rate. One embodiment would define a “ONE” (1) as a short active pulse or a long passive pulse while
`a “ZERO” (0) would be defined as a long active pulse or a short passive pulse. Since a frame is comprised of
`random 1's and 0's, general byte or frame times cannot be predicted in advance.
`
`4.
`
`Abbreviations/Acronyms
`
`BRK: Break
`CRC: Cyclic Redundancy Check
`E/E:
`Electrical and Electronic
`EMC: Electromagnetic Compatibility
`EMI:
`Electromagnetic Interference
`EOD: End of Data
`EOF: End of Frame
`IFR:
`In-Frame Response (Byte/Bytes)
`IFS:
`Inter-Frame Separation
`ISO:
`International Standards Organization
`Kbps: Kilo bits per second
`NA:
`Not Applicable
`NB:
`Normalization Bit
`
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`SAE J1850 Revised MAY2001
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`Open System Interconnect
`OSI:
`SOF: Start of Frame
`
`5.
`
`Description of the Architecture
`
`5.1 General— It is the intent of this network to interconnect different electronic modules on the vehicle using an
`“Open Architecture” approach. An open architecture network is one in which the addition or deletion of one or
`more modules (data nodes) has minimal hardware and/or software impact on the remaining modules.
`
`In order to support an open architecture approach, the Class B network utilizes the concept of Carrier Sense
`Multiple Access (CSMA) with nondestructive contention resolution. Additionally this network supports the
`prioritization of frames such that, in the case of contention, the higher priority frames will always win arbitration
`and be completed.
`
`5.2 Network Topology
`
`5.2.1 DATA BU S T OPOLO GY—Data bus topology is the map of physical connections of the data bus nodes to the
`data bus. It includes all nodes and data buses involved in the data bus integration of the vehicle. A single-
`level bus topology, the simplest bus topology, is currently being used in several automotive applications. In
`a single-level bus topology, all nodes are interconnected via the same data bus. The redundancy
`requirements of a particular application may require a single-level topology to be implemented using multiple
`interconnecting cables operating