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1、GMLANOverview andDiagnostic Test ModesGMLAN Training ObjectivesProvide information to facilitate an basic understanding of GMLAN data links and new functional Tech 2 diagnostic applications. GMLAN Training ContentGMLAN Network ConceptWhat is GMLAN?GMLAN Normal Vehicle CommunicationNode ManagementNet

2、work ManagementGMLAN and Tech 2 Functional DiagnosticsStrategyGMLAN DTC strategy (symptom value)Example screens (from Tech 2 User Interface Specification exerpt word documents)Additional Info included: GMLAN Diagnostic Test Mode Services (w/class 2 comparisons)GMLAN Training ContentGMLAN Network Con

3、ceptWhat Is GMLAN?General Motors In Vehicle Local Area NetworkGMLAN Is A Reliable, Cost Effective, Flexible, And Modular Way To Handle Information Sharing Between Different Electronic Control Units (ECUs) In The Vehicle Through The Means Of A Family Of Serial Communication Buses. GMLAN Communication

4、 Buses Use The Controller Area Network (CAN) ProtocolCAN Developed By Robert Bosch CorporationWhat Is GMLAN? (contd)GMLAN Supports 3 Separate Buses Low SpeedMid SpeedHigh SpeedGateways Between BusesGMLAN Low Speed BusTypically Used For Operator Controlled Functions Where The System Response Time Req

5、uirements Are On The Order Of 100 - 200 msec.Uses Single Wire Physical Media (Also Referred To As Single Wire CAN Or SWCAN)33.33kbps in normal mode, 83.33kbps in high speed programming modeWhat Is GMLAN? (contd)GMLAN Mid Speed BusIntended To Be Used For Infotainment Applications (e.g Graphics Displa

6、y) Where The System Response Time Demands Large Quantities Of Data To Be Transmitted In A Relatively Short Period Of TimeApproximately 95.2kbpsNot Defined At This TimeOpel Epsilon Has Mid Speed Bus Based Off Of IVLAN StrategyMost of the ECUs on this bus are diagnosed via KWP2000What Is GMLAN? (contd

7、)GMLAN High Speed BusTypically Used For Sharing Real Time Data (e.g. Driver Commanded Torque, Actual Engine Torque, Steering Angle, etc.)Primarily Powertrain And Chassis DevicesUses Two Wire Physical MediaWill Operate At 500 kbpsIn Process to e OBD Approved Data LinkWill most likely be the only appr

8、oved OBD data link beginning with MY 2007GMLAN Connector Pin AssignmentsSWCANMS DWCAN+361114HS DWCAN+MS DWCAN-HS DWCAN-GMLAN Communication Busses - contdWhy GM LAN?Common Architecture For GM Vehicles Developed In U.S.A And EuropePromotes Sharing Of Components Developed On Either Side Of The OceanCom

9、mon Communications Protocol On All Buses Easier To Transfer Data From One Bus To AnotherSemiconductor Industry Support Of CANMany Companies Designing uC With Integrated CAN HardwareCAN Protocol Supports Hardware Filtering Of MessagesAvailable On Some CAN ControllersLessens Burden On MicroprocessorWh

10、y GM LAN? (contd)CAN Supports Bus Speeds High Enough To Support Real Time Control FunctionsResults In Reduction Of Hard WiresHigher Bus Speeds Means Greater Bandwidth Which Translates Into More Features Without Additional System LatencySupport Of ECU Wake Up FeaturesAllows ECUs To Enter Low Power St

11、ate When Not Needed.GMLAN Normal Vehicle CommunicationGMLAN Node ManagementNode Management is the process of maintaining a single ECU in a set of predefined communication statesNode startupECU wakes up, initializes its communication and remains in a communication capable state for 8 secondsCommunica

12、tion startupECU monitors the bus for Network Management messages that indicate that other ECUs require the ECU to communicate.Network Management message are not the only method to determine that communication is necessary (can be based on shared hardwires)Node shutdownECU only shuts down when no con

13、trol operations require itGMLAN Network ManagementNetwork Management is the process of maintaining a distributed set of ECUs in predefined communication states.In GMLAN, some ECUs may be communicating while other ECUs are in low power state.Only necessary ECUs are required to communicate for a set o

14、f functionality.Communication between any collection of ECUs can be started or stopped independently of any other collection.These collection of ECUs may be considered “Virtual Networks”.Network Management Example #1Three Virtual Networks, five physical devices, five Virtual DevicesThree independent

15、ly startable sets of functionalityUnnecessary nodes may be powered down until neededNode containing “switch” activates the Virtual Network on demandSwitchSwitchSwitchCompact Disk Virtual Network TunerVirtual Network CassetteVirtual NetworkGMLANAmplifierBackliteAntenna AmpCassetteTuner CDNetwork Mana

16、gement Example #2Three Virtual Networks, four physical devices, five Virtual DevicesUp Integration reduces number of physical devicesUp integration doesnt change number of Virtual DevicesOther Virtual Networks (e.g. CD and Cassette) are unaffected by integrationNetwork Management is independent of p

17、artitioningSwitchSwitchSwitchCompact Disk Virtual Network TunerVirtual Network CassetteVirtual NetworkGMLAN BackliteAntenna AmpCassetteTuner CDAmpl.TunerGMLAN Network Management - contdVirtual Networks are managed using Virtual Network Management Frames (VNMFs) which communicate the Virtual Network

18、activation and initialization requirements of the transmitter.The trigger for the activation of a VN can either be a direct input in the form of an activated switch (e.g. ignition or radio switches), or an indirect input such as a change in a sensor input which is being monitored.One reason for the

19、Virtual Network design is to reduce the power consumption. The ECUs are only powered when a provided functionality is required (Virtual Network activated).It is not required to have the Virtual Network Management scheme implemented on all subnets. GMLAN Wake Up FeatureGMLAN Supports Selective Awake

20、FeatureNodes With Nothing To Do Can Remote Off (enter low power state)GMLAN Strategy Allows Devices To Remote Off After 8 Seconds With No Features ActiveWake Up Required To Bring Node Out Of Low Power StateWake Up Method Varies Based On Type Of GMLAN Bus SWCAN Uses High Voltage Wake Up ($100 CANId)D

21、WCAN Can Use Wake Up Wire, Wake Up On Bus TrafficGMLAN and Tech 2 Functional DiagnosticsGMLAN Diagnostic Message StrategyThe GMLAN Enhanced Diagnostic Test Mode Specification has been targeted to the following objectives:Functional Based Diagnostic Approach to meet distributed system functionality o

22、ver multiple ECUs and in-vehicle subnets.Harmonization of GM J2190 (Class 2) and GM KWP2000 services as One Global GM Corporate Standard.Reduction of total number of diagnostic services (test modes) and utilization of minimum amount of CAN Identifiers for Diagnostics.Optimized performance for testin

23、g and programming (e.g. Parallel testing of ECUs on multiple subnets).Clear split by concept between Dynamic Real-Time Data Retrieval and Multiple Frame Static Data Messages (non time critical data).GMLAN Diagnostic Services, or test modes are designed to provide functionality similar to Class 2, ho

24、wever GMLAN is not identical to Class 2.Mode by mode comparisons are provided at the end of this presentation.Tech 2 Configuration for CAN SupportTech 2 ConfigurationExisting Tech 2Existing VCIExisting DLC cableNew CANdi moduleExisting DLC AdaptersTech 2 Functional System DiagnosticsDecision made to

25、 migrate to strategy of Functional System based diagnostics.In order to support functional system diagnostics, it was requested to implement new features on the Tech 2.Provide navigation sequence which better corresponds to the service manual partitioning of systems. High level partioning into gener

26、al Service Category Types (SCT),Next level partitioning of each Service Category Type into specific systems or “Service Categories” (SC)Tech 2 Functional System DiagnosticsExample of SCT/SC partitioning:Tech 2 Functional System DiagnosticsOther features of Functional System Implementation:Read and d

27、isplay DTCs from all ECUs participating in a specific diagnostic functional system.Verify each ECU communication capability.Display a summary of the number of DTCs reported by each ECU.Provide a combined display of DTCs reported by all ECUs.Prioritize DTCs, and sort the display of DTCs by the priori

28、ty.Provide data display lists each ECU in a specific diagnostic functional system.Combine device control and special functions from multiple ECUs (as necessary for a given functional system).Implementation may have limitations for mixed communication protocols (e.g., a vehicle with both Class 2 and

29、GMLAN data links)Tech 2 Functional System Diagnostics (contd)It was further requested to design and implement a DTC test at a vehicle level (in other words, read DTCs from ALL ECUs on the vehicle in a single test application)Verify each ECU communication capability.Display a summary of the number of

30、 DTCs reported by each ECU.Provide a combined display of DTCs reported by all ECUs.Prioritize DTCs and sort the DTC display according to the priority.Identify the source of each DTC and the related general functional system area.The Functional Diagnostic applications are targeted for first implement

31、ation on Tech 2 to support the Cadillac XLR (2004MY)Note: Not all vehicles with GMLAN capability will have the functional diagnostic implementation on Tech 2 (e.g., Saturn Ion). Migration plan is being developed.Special Note on GMLAN DTC StrategyThe GMLAN DTC strategy is different from other systems

32、 (including Class 2):The GMLAN DTC includes a base DTC number. This is similar to Class 2 DTCs.In GMLAN, however, there is also attached a symptom value. This is a 2 digit hex number value. The GMLAN strategy generally assigns the base DTC number to a specific circuit or vehicle function, with the s

33、ymptom value defining the type of fault detected (e.g., short to ground, open, etc.). Each type of fault has a specific symptom value. The exception to this is for Powertrain DTCs, where a specific DTC base numer is assigned to each individual fault detected. In this case, Powertrain DTCs all have o

34、nly a symptom value of 00 (00 = no additional fault information).The Tech 2 will display the Base DTC number and the symptom value for each GMLAN DTC. (Reference Vehicle DTC Test example document provided)GMLAN Diagnostics ExampleAll Entertainment/Audio Virtual Networks are mapped into one Functiona

35、l System Compact Disk Virtual Network TunerVirtual Network CassetteVirtual NetworkGMLAN BackliteAntenna AmpCassetteCDAmpl.TunerEntertainmentFunctional SystemRefer to Tech 2 Functional System Examples:XLR Navigation example.docVehicle DTC test example.docGMLAN Diagnostic Test Mode Services Overview a

36、nd Class 2 ComparisonGMLAN Diagnostic Test Mode ServicesGMLAN Diagnostic servicesGMLAN Diagnostic Services (contd)Service $04 - Clear Diagnostic InformationCommands a node or nodes to clear diagnostic information.Clears DTC status byte, freeze frame data, failure record information and other DTC rel

37、ated data such as flags, counters, timers, etc. specific to DTCs.Class 2 Similar Service $14GMLAN Diagnostic Services (contd)Service $10 - Initiate Diagnostic OperationDisable the setting of all DTCs while the tester is present.Enable the setting of DTCs during device control.Request a gateway ECU t

38、o issue a wake up request.Class 2 Similar Service $10GMLAN Diagnostic Services (contd)Service $12 - Read Failure Record DataAllows access to failure record information stored as a result of a DTC being set.Supports PID or DPID format.Class 2 Similar Service $12GMLAN Diagnostic Services (contd)Servic

39、e $1A - Read Data By IdentifierAllows reading the content of pre-defined ECU data referenced by a Data Identifier (DID).The data read by this service is static (does not require real-time updates) such as ECU identification data.GMW 3110 Appendix C Contains List Of Corporate Defined Data Identifiers

40、Class 2 Similar Service $3CGMLAN Diagnostic Services (contd)Service $20 - Return to Normal OperationCancels all active diagnostic services and resets normal message communications.Services which do not require the tester present messages are unaffected by this service.This mode is simulated by a tes

41、ter present ($3E) time-out (5 seconds without receiving a $3E).Causes all ECUs to perform a software reset when used to conclude a programming eventClass 2 Similar Service $20GMLAN Diagnostic Services (contd)Service $23 - Read Memory by AddressAllows access to current data from a contiguous range of

42、 memory (RAM, Calibrations, and unprotected EEPROM and Flash) addresses. The range of addresses is specified by either a two, three, or four byte starting address and a two byte length.The CTS is required to specify the number of bytes needed for the address informationThis mode is intended to be us

43、ed during a devices development cycle to allow access to data that may not be available through another diagnostic service. (not intended for field diag.)Class 2 Similar Service $23 Except 4 Byte Addressing Is Now AllowedGMLAN Diagnostic Services (contd)Service $27 - Security AccessSeed & Key device

44、 security (algorithm must be external to device).Restricts unauthorized access to various data and diagnostic services within the device.Diagnostic services for downloading routines or data and reading specific memory locations from a device are examples which may require security access.Device Cont

45、rol Overrides Handled With $27Class 2 Similar Service $27, $A8GMLAN Diagnostic Services (contd)Service $28 - Disable Normal Comm. Prevents a device from transmitting or receiving all messages which are not the direct result of a diagnostic request.This service is primarily used to set up a programmi

46、ng event.This service disables the setting of all diagnostic trouble codes. A device receiving and complying with this request shall take failsoft action on all necessary parameters.Class 2 Similar Service $28GMLAN Diagnostic Services (contd)Service $2C - Dynamically Define Message Required to dynam

47、ically define diagnostic data packets (DPID) which are formatted as UUDT messages.The device shall retain the contents of dynamic DPIDs upon a $3E time-out or the receipt of a $20 service request message.Allows optimized diagnostic routines and bus bandwidth utilization. Single Request To Define DPI

48、DClass 2 Similar Service $2CGMLAN Diagnostic Services (contd)Service $34 - Request DownloadPrepares a node to receive a download of a block of data.Only a single $34 service request is required to initiate a download sequence of multiple software or calibration modules to a node.Class 2 Similar Serv

49、ice $34 Except 4 Byte Addressing Is Now AllowedGMLAN Diagnostic Services (contd)Service $36 - Transfer DataThis service is used to transfer and/or execute a block of data.Data blocks: maximum of (4093 - Address Size) bytes.Class 2 Similar Service $36 Except 4 Byte Addressing Is Now AllowedGMLAN Diag

50、nostic Services (contd)Service $3E - Tester PresentInforms a device or devices that a tester is still connected to the vehicle by resetting the diagnostic timer.Receipt of the $3E Tester Present message does not put a node in diagnostic modeNo Response If Requested via Functional AddressingResponse

51、Provided If Physically RequestedClass 2 Similar Service $3FGMLAN Diagnostic Services (contd)Service $7F - Negative ResponseOnly A Response MessageProvides Reason Why Request Message Was RejectedAllowed Negative Response Codes Documented In GMW 3110Also Used To Provide Response Code For Device Contro

52、l Limits Exceeded (This Is Different From Class 2)Only Service Id From Request Is KeptClass 2 Similar Service $7FGMLAN Diagnostic Services (contd)Service $A2 - Report Programming StateUsed to report which nodes on the link are programmable and the current programmed state of each of these nodes.Opti

53、on: can also report programmable memory fault conditionsUsed To Enable SPS Prime CANIdsMust Be Requested. In Class 2 This was An Unsolicited MessageSimilar Class 2 Service $A2GMLAN Diagnostic Services (contd)Service $A5 - Programming ModeVerifies that all criteria are met to enable the programming s

54、ervices for all receiving nodes.Enables the high speed mode of operation for all receiving nodes on Single Wire CAN.Enables the programming services for all receiving nodes.Class 2 Similar Service(s) $A0 & $A1GMLAN Diagnostic Services (contd)Service $A9 - Read Diagnostic InformationUses UUDT Response Message FormatRetrieve the sta