A Comparison of J1939 & ISO15031

Jeff CraigVector CANtech, Inc.

Agenda

DiagnosticStandards PhysicalInterface Connectors Terminology ProtocolOverview FaultCodes

HistoryLesson

Whatisthis??

1980sAutomotiveDiagnosticTool

MajorDifferences

J1939(MD&HDTruck) ISO15031(PassCar&LDVehicles)

AllstandardsdefinedinSAEJ1939parts ISO15031isharmonizedwithseveralSAEstds.

29bitidentifiers 11bitidentifiers

Usedfornormalcommunications&diagnostics Usedonlyfordiagnostics

Faultstatusbroadcastregularly(e.g.DM1) Nobroadcastmessages

PrimaryfunctionalitydefinedusingDiagnosticMessages(DMs)

PrimaryfunctionalitydefinedusinguniquecommunicationServiceIDs(SIDs)

3bytefaultcodes+occurrencecounter 3bytefaultcodes

Fourwarninglampsdefined Onewarninglampdefined

250Kbpsbusspeed 500Kbpsbusspeed

Ninepindiagconnectorstandard

(J193913)

Sixteenpindiag connectorstandard(ISO150313/J1962)

DiagnosticStandards

DiagnosticStandards:Car/Truck SAE/ISOSAE ISO

PassCar&LDVeh

J1930 terms&defns

J1962 connector

J1978 scantool

J1979 diagservices

J2012 faultcodes

J2186 linksecurity

J2534 passthru

J1699 OBDconformance

ISO11898(5parts) CAN

ISO15765(4parts)DiagnosticsonCAN

ISO15031(7parts)LegislatedOBDonCAN

MD&HDVehJ1939(Multipleparts)

J2403 terms&defnsN/A

In some cases multiple standards will be mixed on the same vehicle

Apples to ApplesOSILayer

MD&HDStandards&OBDLegislated

PassCar&LDOBDLegislated

N/ADiagnostic

ConnectorSAEJ193913 ISO150313

7 ApplicationSAEJ193971/73

SAEJ193981ISO150315

(SAEJ1979)

6 Presentation ISO150315(SAEJ1979)

5 Session ISO157654

4Transport

ProtocolSAEJ193921 ISO157652

3Network

LayerSAEJ193931 ISO157654

2 DataLink SAEJ193921(ISO118981)

ISO157654(ISO118981)

1 PhysicalLayer SAEJ193911/15 ISO157654(ISO118982)

ISO15031MappingtoSAEStandards

H A R M O N I Z E D

ISO 15031

J1930Terms &

Definitions

SAE Recommended Practice

J1962Diagnostic Connector

J1978Diag Tool Reqmnts

J1979Diagnostic Services

J2012Fault Code Definitions

J2186Data Link Security

2 3 4 5 6 7

PhysicalInterface

PhysicalInterface

J1939 11or15ISO150313,ISO118982

&ISO157654250Kbps 500Kbps

TwistedShieldedPair(11)

TwistedUnshieldedPair(15)TwistedPair noshield

Max30ECUs(11)

Max10ECUs(15)NoMaxDefined

40mTotalNWLength40m@1Mbps Longerallowed

atlowerspeeds

1mStubLength(11)

3mStubLength(15).3m@1Mbps Longerallowedat

lowerspeeds

Connectors

Connectors

1 2 3 4 5 6 7 89 10 11 12 13 14 15 16ISO 15031 3

(J1962)

J1939 - 13AB

CD

E

FG

H

J

Terminology

Terminology JustaFewJ1939 ISO15031

ACL=AddressClaiming

BAM=BroadcastAnnounceMessage

DM=DiagnosticMessage

DP=DataPage

DTC=DiagnosticTroubleCode

ECU=ElectronicControlUnit

EDP=ExtendedDataPage

FMI=FailureModeIdentifier

NACK=NegativeAcknowledgement

PDU=ProtocolDataUnit

PG=ParameterGroup

PGN=ParameterGroupNumber

SLOT=Scaling,Limit,Offset&Transfer

SPN=SuspectParameterNumber

DLC=DataLengthCode

DTC=DiagnosticTroubleCode

ECM=EngineControlModule

ECU=ElectronicControlModule

FTB=FailureTypeByte

KWP=KeyWordProtocol(ISO14230)

MIL=MalfunctionIndicatorLamp

NRC=NegativeResponseCode

PCI=ProtocolControlInformation

PID=ParameterID(similartoDIDorLID)

SID=ServiceID

ProtocolOverview

CANMessageStructure11 bit or 29 bit

StandardCANFormat:11BitIdentifier

UsageforOBD:ECUIdentification FunctionalRequestIDforOBDdiagnosticrequests(sourceaddress

notrequiredsinceonlyonediagnostictesterisallowedonthebusatonetime)

SourceECUIDfordiagnosticresponsesMostOEMshavetheirownIDassignmentstandards

PresenterPresentation NotesJ1939 has a different construct to do CAN Remote Frame activity

J1939ExtendedCANFormat:29BitIdentifier

ThreeComponents asdefinedbyJ1939: MessagePriority ParameterGroupNumber(DefinesthedataintheDATAarea

SAEstandardized&proprietaryPGNspossible) SourceAddress

Interpretation of 29 Bit CAN Extended Identifier in J1939

PDU Format < 0xF0 defines message as Peer-to-Peer. PDU Specific will be a Destination Address

PDU Format => 0xF0 identifies message as broadcast. PDU Specific will be a Group Extension

EDP(1 Bit)

Priority(3 Bit)

DP(1 Bit)

PDU Format(8 Bit)

PDU Specific(8 Bit)

Source Address(8 Bit)

Bit 28Bit 0

PGN

J193929BitIdentifierDefined

PresenterPresentation NotesData page:The Data Page (DP) and the Extended Data Page (EDP) bit expand the value of available parameter groups. The SAE J1939 standard defines the following data pages:

EDPDPUsage00Default Data page. Used from SAEJ1939 and ISO11783 01Mostly used from NMEA2000.10Reserved for SAEJ1939.11Reserved for ISO.

Manufacturer specific communication:Some options are possible:Using the 11-Bit CAN IdentifierUsing reserved parameter group numbers

Optional PGNs:Only the 2 at present available data pages are used for the examples.

Tester ECU

Cyclic Diagnostic Messages (e.g. DM1)J1939

[[Prio + Request PGN + Dest Addr + Src Addr] [Requested PGN]]

- or -

ECUTester

ISO 15031

[[Target ID] [Requested Service + Requested Data]]

[[Source ID] [Requested Service ID + Requested Data]]

(Services can be data requests, fault code requests, output control, special test requests, security access, reprogramming requests, etc.)

[[Prio + Requested PGN + Dest Addr + Src Addr] [PGN Data]]

DiagnosticMessageStructureComparison

FaultCodes

8 7 6 5 4 3 2 18 7 6 5 4 3 2 1 8 7 6 5 4 3 2 1 8 7 6 5 4 3 2 1

DTC

Byte 1 Byte 2 Byte 3 Byte 4

SPN FMICM OC

MSB LSB

Low Byte SPN

Mid Byte SPN

MSB LSB

3 MSB of SPN

+FMI

Conversion Method

+Occurance

Count

Conversion Method Bit Affects the Interpretation of the Byte Ordering

of the SPN (0 since 1996)

J1939DiagnosticTroubleCode

PresenterPresentation NotesINTEL FORMAT! note the bit/byte ordering

ISO15031DiagnosticTroubleCode

8 7 6 5 4 3 2 1 8 7 6 5 4 3 2 1 8 7 6 5 4 3 2 1

DTC

Byte 1 Byte 2 Byte 3

SAE Code Number FTB

1st Character of SAE Code (P,C,B,U)

2nd Character of SAE Code (0,1,2,3)

3rd Character of SAE Code (0-F)

4th Character of SAE Code (0-F)

5th Character of SAE Code (0-F)

PresenterPresentation NotesINTEL FORMAT! note the bit/byte ordering

ThankYou

JeffCraigVectorCANtech

jeff.craig@vector.com

Slide Number 1AgendaHistory LessonMajor DifferencesSlide Number 5Diagnostic Standards: Car/Truck SAE/ISOApples to - ApplesISO 15031 Mapping to SAE StandardsSlide Number 9Physical InterfaceSlide Number 11ConnectorsTerminologyTerminology Just a FewProtocol OverviewCAN Message StructureStandard CAN Format: 11-Bit IdentifierJ1939 Extended CAN Format: 29-Bit IdentifierSlide Number 19Slide Number 20Fault CodesJ1939 Diagnostic Trouble CodeISO 15031 Diagnostic Trouble CodeThank YouJeff CraigVector CANtechjeff.craig@vector.com