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Decode J1939 Data from BLF-Files

This example shows you how to import and decode J1939 data from BLF-files in MATLAB for analysis. The BLF-file used in this example was generated from Vector CANoe using the "System Configuration (J1939)" sample. This example also uses the CAN database file, Powertrain_J1939_BLF.dbc, provided with the Vector sample configuration.

Investigate the BLF-File

Retrieve and view information about the BLF-file. The blfinfo function parses general information about the format and contents of the Vector Binary Logging Format BLF-file and returns the information as a structure.

binf = blfinfo("LoggingBLF_J1939.blf")
binf = struct with fields:
                  Name: "LoggingBLF_J1939.blf"
                  Path: "C:\Users\michellw\OneDrive - MathWorks\Documents\MATLAB\Examples\vnt-ex52809946\LoggingBLF_J1939.blf"
           Application: "CANoe"
    ApplicationVersion: "12.0.167"
               Objects: 131119
             StartTime: 21-Apr-2021 10:05:13.232
               EndTime: 21-Apr-2021 10:09:14.344
           ChannelList: [2×3 table]

Notice the ChannelList property indicates there are 2 channels referenced in the BLF-file with ChannelID values of 1 and 2. The J1939 powertrain data of interest was logged from the CAN2 network, so this example focuses on ChannelID 2.

binf.ChannelList
ans=2×3 table
    ChannelID    Protocol    Objects
    _________    ________    _______

        1         "CAN"       92720 
        2         "CAN"       26054 

J1939 is a protocol built on top of the CAN protocol. A parameter group (PG) is a set of parameters belonging to the same topic and sharing the same transmission rate e.g. EngCoolantTemp, EngFuelTemp, EngTurboOilTemp, etc. of the ET1_EMS PG (see the ET1_EMS PG in signalTimetables below). Each parameter group is addressed via a unique number called the parameter group number (PGN). J1939 PGs are transmitted as CAN frames.

Read J1939 CAN Data Frames From the BLF-File

Read all data from channel 2 into a timetable using the blfread function. Each row of the timetable represents one raw CAN frame from the bus.

canData = blfread("LoggingBLF_J1939.blf", 2)
canData=26054×8 timetable
        Time           ID        Extended       Name                      Data                    Length      Signals       Error    Remote
    ____________    _________    ________    __________    ___________________________________    ______    ____________    _____    ______

    0.000568 sec    418316262     true       {0×0 char}    {[      105 52 169 232 0 131 0 16]}      8       {0×0 struct}    false    false 
    0.27057 sec     418383078     true       {0×0 char}    {[  255 255 255 208 7 255 255 255]}      8       {0×0 struct}    false    false 
    0.29057 sec     418383078     true       {0×0 char}    {[  255 255 255 208 7 255 255 255]}      8       {0×0 struct}    false    false 
    0.30058 sec     418382822     true       {0×0 char}    {[  255 0 255 255 255 255 255 255]}      8       {0×0 struct}    false    false 
    0.30116 sec     419327206     true       {0×0 char}    {[255 255 255 255 255 255 255 255]}      8       {0×0 struct}    false    false 
    0.31057 sec     418383078     true       {0×0 char}    {[  255 255 255 208 7 255 255 255]}      8       {0×0 struct}    false    false 
    0.33057 sec     418383078     true       {0×0 char}    {[  255 255 255 208 7 255 255 255]}      8       {0×0 struct}    false    false 
    0.35058 sec     418382822     true       {0×0 char}    {[  255 0 255 255 255 255 255 255]}      8       {0×0 struct}    false    false 
    0.35115 sec     418383078     true       {0×0 char}    {[  255 255 255 208 7 255 255 255]}      8       {0×0 struct}    false    false 
    0.35173 sec     419327206     true       {0×0 char}    {[255 255 255 255 255 255 255 255]}      8       {0×0 struct}    false    false 
    0.3523 sec      419361254     true       {0×0 char}    {[     255 0 0 12 255 255 224 255]}      8       {0×0 struct}    false    false 
    0.37057 sec     418383078     true       {0×0 char}    {[  255 255 255 208 7 255 255 255]}      8       {0×0 struct}    false    false 
    0.39057 sec     418383078     true       {0×0 char}    {[  255 255 255 208 7 255 255 255]}      8       {0×0 struct}    false    false 
    0.40058 sec     418382822     true       {0×0 char}    {[  255 0 255 255 255 255 255 255]}      8       {0×0 struct}    false    false 
    0.40116 sec     419327206     true       {0×0 char}    {[255 255 255 255 255 255 255 255]}      8       {0×0 struct}    false    false 
    0.41057 sec     418383078     true       {0×0 char}    {[  255 255 255 208 7 255 255 255]}      8       {0×0 struct}    false    false 
      ⋮

Decode J1939 Parameter Groups Using the DBC-File

Open the database file using the canDatabase function.

canDB = canDatabase("Powertrain_J1939_BLF.dbc")
canDB = 
  Database with properties:

             Name: 'Powertrain_J1939_BLF'
             Path: 'C:\Users\michellw\OneDrive - MathWorks\Documents\MATLAB\Examples\vnt-ex52809946\Powertrain_J1939_BLF.dbc'
            Nodes: {12×1 cell}
         NodeInfo: [12×1 struct]
         Messages: {93×1 cell}
      MessageInfo: [93×1 struct]
       Attributes: {3×1 cell}
    AttributeInfo: [3×1 struct]
         UserData: []

The j1939ParameterGroupTimetable function uses the database to decode the raw CAN Data into PGs, PGNs and signals. The timetable of binary logging format data is converted into a Vehicle Network Toolbox™ J1939 parameter group timetable.

j1939PGTimetable = j1939ParameterGroupTimetable(canData, canDB)
j1939PGTimetable=26030×8 timetable
        Time          Name       PGN     Priority        PDUFormatType        SourceAddress    DestinationAddress                   Data                      Signals   
    ____________    ________    _____    ________    _____________________    _____________    __________________    ___________________________________    ____________

    0.000568 sec    ACL         60928       6        Peer-to-Peer (Type 1)         230                255            {[      105 52 169 232 0 131 0 16]}    {1×1 struct}
    0.27057 sec     EEC1_EMS    61444       6        Broadcast (Type 2)            230                255            {[  255 255 255 208 7 255 255 255]}    {1×1 struct}
    0.29057 sec     EEC1_EMS    61444       6        Broadcast (Type 2)            230                255            {[  255 255 255 208 7 255 255 255]}    {1×1 struct}
    0.30058 sec     EEC2_EMS    61443       6        Broadcast (Type 2)            230                255            {[  255 0 255 255 255 255 255 255]}    {1×1 struct}
    0.30116 sec     TCO1_TCO    65132       6        Broadcast (Type 2)            230                255            {[255 255 255 255 255 255 255 255]}    {1×1 struct}
    0.31057 sec     EEC1_EMS    61444       6        Broadcast (Type 2)            230                255            {[  255 255 255 208 7 255 255 255]}    {1×1 struct}
    0.33057 sec     EEC1_EMS    61444       6        Broadcast (Type 2)            230                255            {[  255 255 255 208 7 255 255 255]}    {1×1 struct}
    0.35058 sec     EEC2_EMS    61443       6        Broadcast (Type 2)            230                255            {[  255 0 255 255 255 255 255 255]}    {1×1 struct}
    0.35115 sec     EEC1_EMS    61444       6        Broadcast (Type 2)            230                255            {[  255 255 255 208 7 255 255 255]}    {1×1 struct}
    0.35173 sec     TCO1_TCO    65132       6        Broadcast (Type 2)            230                255            {[255 255 255 255 255 255 255 255]}    {1×1 struct}
    0.3523 sec      CCVS_EMS    65265       6        Broadcast (Type 2)            230                255            {[     255 0 0 12 255 255 224 255]}    {1×1 struct}
    0.37057 sec     EEC1_EMS    61444       6        Broadcast (Type 2)            230                255            {[  255 255 255 208 7 255 255 255]}    {1×1 struct}
    0.39057 sec     EEC1_EMS    61444       6        Broadcast (Type 2)            230                255            {[  255 255 255 208 7 255 255 255]}    {1×1 struct}
    0.40058 sec     EEC2_EMS    61443       6        Broadcast (Type 2)            230                255            {[  255 0 255 255 255 255 255 255]}    {1×1 struct}
    0.40116 sec     TCO1_TCO    65132       6        Broadcast (Type 2)            230                255            {[255 255 255 255 255 255 255 255]}    {1×1 struct}
    0.41057 sec     EEC1_EMS    61444       6        Broadcast (Type 2)            230                255            {[  255 255 255 208 7 255 255 255]}    {1×1 struct}
      ⋮

View the signal data stored in the third PG of the timetable, which is one instance of the "EEC1_EMS" PG.

signalData = j1939PGTimetable.Signals{3}
signalData = struct with fields:
             EngDemandPercentTorque: 130
                     EngStarterMode: 15
    SrcAddrssOfCtrllngDvcForEngCtrl: 255
                           EngSpeed: 250
             ActualEngPercentTorque: 130
      DriversDemandEngPercentTorque: 130
                      EngTorqueMode: 15

Repackage and Visualize Signal Values of Interest

Use the j1939SignalTimetable function to repackage signal data from each unique PGN on the bus into a signal timetable. This example creates two individual signal timetables for the two PGs of interest, "EEC1_EMS" and "TCO1_TCO", from the J1939 PG timetable.

signalTimetable1 = j1939SignalTimetable(j1939PGTimetable, "ParameterGroups", "EEC1_EMS")
signalTimetable1=12043×7 timetable
       Time        EngDemandPercentTorque    EngStarterMode    SrcAddrssOfCtrllngDvcForEngCtrl    EngSpeed    ActualEngPercentTorque    DriversDemandEngPercentTorque    EngTorqueMode
    ___________    ______________________    ______________    _______________________________    ________    ______________________    _____________________________    _____________

    0.27057 sec             130                    15                        255                    250                130                           130                      15      
    0.29057 sec             130                    15                        255                    250                130                           130                      15      
    0.31057 sec             130                    15                        255                    250                130                           130                      15      
    0.33057 sec             130                    15                        255                    250                130                           130                      15      
    0.35115 sec             130                    15                        255                    250                130                           130                      15      
    0.37057 sec             130                    15                        255                    250                130                           130                      15      
    0.39057 sec             130                    15                        255                    250                130                           130                      15      
    0.41057 sec             130                    15                        255                    250                130                           130                      15      
    0.43057 sec             130                    15                        255                    250                130                           130                      15      
    0.45115 sec             130                    15                        255                    250                130                           130                      15      
    0.47057 sec             130                    15                        255                    250                130                           130                      15      
    0.49057 sec             130                    15                        255                    250                130                           130                      15      
    0.51057 sec             130                    15                        255                    250                130                           130                      15      
    0.53057 sec             130                    15                        255                    250                130                           130                      15      
    0.55115 sec             130                    15                        255                    250                130                           130                      15      
    0.57057 sec             130                    15                        255                    250                130                           130                      15      
      ⋮

signalTimetable2 = j1939SignalTimetable(j1939PGTimetable, "ParameterGroups", "TCO1_TCO")
signalTimetable2=4817×14 timetable
       Time        TachographVehicleSpeed    TachographOutputShaftSpeed    DirectionIndicator    TachographPerformance    HandlingInformation    SystemEvent    DriverCardDriver2    Driver2TimeRelatedStates    Overspeed    DriverCardDriver1    Driver1TimeRelatedStates    DriveRecognize    Driver2WorkingState    Driver1WorkingState
    ___________    ______________________    __________________________    __________________    _____________________    ___________________    ___________    _________________    ________________________    _________    _________________    ________________________    ______________    ___________________    ___________________

    0.30116 sec             256                        8191.9                      3                       3                       3                  3                 3                       15                   3                3                       15                     3                    7                      7         
    0.35173 sec             256                        8191.9                      3                       3                       3                  3                 3                       15                   3                3                       15                     3                    7                      7         
    0.40116 sec             256                        8191.9                      3                       3                       3                  3                 3                       15                   3                3                       15                     3                    7                      7         
    0.45173 sec             256                        8191.9                      3                       3                       3                  3                 3                       15                   3                3                       15                     3                    7                      7         
    0.50116 sec             256                        8191.9                      3                       3                       3                  3                 3                       15                   3                3                       15                     3                    7                      7         
    0.55173 sec             256                        8191.9                      3                       3                       3                  3                 3                       15                   3                3                       15                     3                    7                      7         
    0.60116 sec             256                        8191.9                      3                       3                       3                  3                 3                       15                   3                3                       15                     3                    7                      7         
    0.65173 sec             256                        8191.9                      3                       3                       3                  3                 3                       15                   3                3                       15                     3                    7                      7         
    0.70116 sec             256                        8191.9                      3                       3                       3                  3                 3                       15                   3                3                       15                     3                    7                      7         
    0.75173 sec             256                        8191.9                      3                       3                       3                  3                 3                       15                   3                3                       15                     3                    7                      7         
    0.80116 sec             256                        8191.9                      3                       3                       3                  3                 3                       15                   3                3                       15                     3                    7                      7         
    0.85173 sec             256                        8191.9                      3                       3                       3                  3                 3                       15                   3                3                       15                     3                    7                      7         
    0.90116 sec             256                        8191.9                      3                       3                       3                  3                 3                       15                   3                3                       15                     3                    7                      7         
    0.95173 sec             256                        8191.9                      3                       3                       3                  3                 3                       15                   3                3                       15                     3                    7                      7         
    1.0012 sec              256                        8191.9                      3                       3                       3                  3                 3                       15                   3                3                       15                     3                    7                      7         
    1.0517 sec              256                        8191.9                      3                       3                       3                  3                 3                       15                   3                3                       15                     3                    7                      7         
      ⋮

You can alternatively choose to convert the whole J1939 PG timetable into a struct containing multiple J1939 signal timetables for each individual PG, and index into it to get data for a particular PG.

signalTimetables = j1939SignalTimetable(j1939PGTimetable)
signalTimetables = struct with fields:
          ACL: [1×14 timetable]
     CCVS_EMS: [2408×19 timetable]
           DD: [240×5 timetable]
     EEC1_EMS: [12043×7 timetable]
     EEC2_EMS: [4817×10 timetable]
      ET1_EMS: [240×6 timetable]
    HOURS_EMS: [240×2 timetable]
      LFC_EMS: [480×2 timetable]
         SERV: [240×6 timetable]
     TCO1_TCO: [4817×14 timetable]
     VDHR_EMS: [240×2 timetable]
       VI_EMS: [24×1 timetable]
       VW_SSC: [240×4 timetable]

signalTimetables.EEC1_EMS
ans=12043×7 timetable
       Time        EngDemandPercentTorque    EngStarterMode    SrcAddrssOfCtrllngDvcForEngCtrl    EngSpeed    ActualEngPercentTorque    DriversDemandEngPercentTorque    EngTorqueMode
    ___________    ______________________    ______________    _______________________________    ________    ______________________    _____________________________    _____________

    0.27057 sec             130                    15                        255                    250                130                           130                      15      
    0.29057 sec             130                    15                        255                    250                130                           130                      15      
    0.31057 sec             130                    15                        255                    250                130                           130                      15      
    0.33057 sec             130                    15                        255                    250                130                           130                      15      
    0.35115 sec             130                    15                        255                    250                130                           130                      15      
    0.37057 sec             130                    15                        255                    250                130                           130                      15      
    0.39057 sec             130                    15                        255                    250                130                           130                      15      
    0.41057 sec             130                    15                        255                    250                130                           130                      15      
    0.43057 sec             130                    15                        255                    250                130                           130                      15      
    0.45115 sec             130                    15                        255                    250                130                           130                      15      
    0.47057 sec             130                    15                        255                    250                130                           130                      15      
    0.49057 sec             130                    15                        255                    250                130                           130                      15      
    0.51057 sec             130                    15                        255                    250                130                           130                      15      
    0.53057 sec             130                    15                        255                    250                130                           130                      15      
    0.55115 sec             130                    15                        255                    250                130                           130                      15      
    0.57057 sec             130                    15                        255                    250                130                           130                      15      
      ⋮

To visualize a signal of interest, variables from the signal timetables can be plotted over time for further analysis. For this example, look at the "EngineSpeed" signal from the "EEC1_EMS" PG.

plot(signalTimetable1.Time, signalTimetable1.EngSpeed, "r")
title("{\itEngineSpeed} signal from {\itEEC1\_EMS} PG", "FontWeight", "bold")
xlabel("Timestamp")
ylabel("Engine Speed")

Close the File

Close access to the DBC-file by clearing its variable from the workspace.

clear canDB