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Decoding CAN Data from BLF-Files

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

Open the Database File

Open the database file describing the source CAN network using the canDatabase function.

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

             Name: 'PowerTrain_BLF'
             Path: 'C:\Users\rschupba\OneDrive - MathWorks\Documents\MATLAB\Examples\vnt-ex06202590\PowerTrain_BLF.dbc'
            Nodes: {2×1 cell}
         NodeInfo: [2×1 struct]
         Messages: {12×1 cell}
      MessageInfo: [12×1 struct]
       Attributes: {11×1 cell}
    AttributeInfo: [11×1 struct]
         UserData: []

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("Logging_BLF.blf")
binf = struct with fields:
                  Name: "Logging_BLF.blf"
                  Path: "C:\Users\rschupba\OneDrive - MathWorks\Documents\MATLAB\Examples\vnt-ex06202590\Logging_BLF.blf"
           Application: "CANoe"
    ApplicationVersion: "11.0.55"
               Objects: 43344
             StartTime: 01-Jul-2020 14:47:34.427
               EndTime: 01-Jul-2020 14:48:33.487
           ChannelList: [2×3 table]

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

        1         "CAN"       8801  
        2         "CAN"       7575  

Read Data from BLF-File

The data of interest was logged from the powertrain bus which is stored in channel 2 of the BLF-file. Read the CAN data using the blfread function. You can also provide the DBC-file to the function call which will enable message name lookup and signal value decoding.

blfData = blfread("Logging_BLF.blf", 2, "Database", canDB)
blfData=7575×8 timetable
       Time        ID     Extended           Name              Data        Length      Signals       Error    Remote
    __________    ____    ________    __________________    ___________    ______    ____________    _____    ______

    2.2601 sec     103     false      {'Ignition_Info' }    {1×2 uint8}      2       {1×1 struct}    false    false 
    2.2801 sec     103     false      {'Ignition_Info' }    {1×2 uint8}      2       {1×1 struct}    false    false 
    2.3002 sec     100     false      {'EngineData'    }    {1×8 uint8}      8       {1×1 struct}    false    false 
    2.3005 sec     102     false      {'EngineDataIEEE'}    {1×8 uint8}      8       {1×1 struct}    false    false 
    2.3006 sec     103     false      {'Ignition_Info' }    {1×2 uint8}      2       {1×1 struct}    false    false 
    2.3008 sec     201     false      {'ABSdata'       }    {1×6 uint8}      6       {1×1 struct}    false    false 
    2.3009 sec    1020     false      {'GearBoxInfo'   }    {[      1]}      1       {1×1 struct}    false    false 
    2.3201 sec     103     false      {'Ignition_Info' }    {1×2 uint8}      2       {1×1 struct}    false    false 
    2.3401 sec     103     false      {'Ignition_Info' }    {1×2 uint8}      2       {1×1 struct}    false    false 
    2.3502 sec     100     false      {'EngineData'    }    {1×8 uint8}      8       {1×1 struct}    false    false 
    2.3505 sec     102     false      {'EngineDataIEEE'}    {1×8 uint8}      8       {1×1 struct}    false    false 
    2.3507 sec     201     false      {'ABSdata'       }    {1×6 uint8}      6       {1×1 struct}    false    false 
    2.3508 sec    1020     false      {'GearBoxInfo'   }    {[      1]}      1       {1×1 struct}    false    false 
    2.3601 sec     103     false      {'Ignition_Info' }    {1×2 uint8}      2       {1×1 struct}    false    false 
    2.3801 sec     103     false      {'Ignition_Info' }    {1×2 uint8}      2       {1×1 struct}    false    false 
    2.4002 sec     100     false      {'EngineData'    }    {1×8 uint8}      8       {1×1 struct}    false    false 
      ⋮

View signals from an "EngineData" message.

blfData.Signals{3}
ans = struct with fields:
    PetrolLevel: 1
       EngPower: 7.5000
       EngForce: 0
    IdleRunning: 0
        EngTemp: 0
       EngSpeed: 750

Repackage and Visualize Signal Values of Interest

Use the canSignalTimetable function to repackage signal data from each unique message on the bus into a signal timetable. This example creates three individual signal timetables for the three messages of interest, "ABSdata", "EngineData" and "GearBoxInfo", from the CAN message timetable.

signalTimetable1 = canSignalTimetable(blfData, "ABSdata")
signalTimetable1=1136×4 timetable
       Time       AccelerationForce    Diagnostics    GearLock    CarSpeed
    __________    _________________    ___________    ________    ________

    2.3008 sec          -100                0            0            0   
    2.3507 sec           275                0            0            0   
    2.4008 sec           275                0            0            0   
    2.4507 sec           275                0            0            0   
    2.5008 sec           275                0            0            0   
    2.5507 sec           275                0            0            0   
    2.6008 sec           275                0            0            0   
    2.6507 sec           275                0            0            0   
    2.7008 sec           350                0            0            0   
    2.7507 sec           425                0            0          0.5   
    2.8008 sec           425                0            0          0.5   
    2.8507 sec           500                0            0          0.5   
    2.9008 sec           575                0            0          0.5   
    2.9507 sec           575                0            0          0.5   
    3.0008 sec           650                0            0          0.5   
    3.0507 sec           725                0            0          0.5   
      ⋮

signalTimetable2 = canSignalTimetable(blfData, "EngineData")
signalTimetable2=1136×6 timetable
       Time       PetrolLevel    EngPower    EngForce    IdleRunning    EngTemp    EngSpeed
    __________    ___________    ________    ________    ___________    _______    ________

    2.3002 sec         1            7.5          0            0            0         750   
    2.3502 sec         2            7.5        375            0            0           4   
    2.4002 sec         3            7.5        375            0            0          10   
    2.4502 sec         4            7.5        375            0            0          17   
    2.5002 sec         5            7.5        375            0            0          23   
    2.5502 sec         6            7.5        375            0            0          30   
    2.6002 sec         7            7.5        375            0            0          36   
    2.6502 sec         8            7.5        375            0            0          43   
    2.7002 sec         9              9        450            0            0          50   
    2.7502 sec        10           10.5        525            0            0          59   
    2.8002 sec        10           10.5        525            0            0          69   
    2.8502 sec        11             12        600            0            0          80   
    2.9002 sec        11           13.5        675            0            0          92   
    2.9502 sec        12           13.5        675            0            0         106   
    3.0002 sec        13             15        750            0            0         121   
    3.0502 sec        13           16.5        825            0            0         136   
      ⋮

signalTimetable3 = canSignalTimetable(blfData, "GearBoxInfo")
signalTimetable3=1136×3 timetable
       Time       EcoMode    ShiftRequest    Gear
    __________    _______    ____________    ____

    2.3009 sec       0            0           1  
    2.3508 sec       0            0           1  
    2.4009 sec       0            0           1  
    2.4508 sec       0            0           1  
    2.5009 sec       0            0           1  
    2.5508 sec       0            0           1  
    2.6009 sec       0            0           1  
    2.6508 sec       0            0           1  
    2.7009 sec       0            0           1  
    2.7508 sec       0            0           1  
    2.8009 sec       0            0           1  
    2.8508 sec       0            0           1  
    2.9009 sec       0            0           1  
    2.9508 sec       0            0           1  
    3.0009 sec       0            0           1  
    3.0508 sec       0            0           1  
      ⋮

To visualize the signals of interest, columns from the signal timetables can be plotted over time for further analysis.

subplot(3, 1, 1)
plot(signalTimetable1.Time, signalTimetable1.CarSpeed, 'r')
title('{\itCarSpeed} Signal from {\itABSdata} Message', 'FontWeight', 'bold')
xlabel('Timestamp')
ylabel('Car Speed')
subplot(3, 1, 2)
plot(signalTimetable2.Time, signalTimetable2.EngSpeed, 'b')
title('{\itEngSpeed} Signal from {\itEngData} Message', 'FontWeight', 'bold')
xlabel('Timestamp')
ylabel('Engine Speed')
subplot(3, 1, 3)
plot(signalTimetable3.Time, signalTimetable3.Gear, 'y')
title('{\itGear} Signal from {\itGearBoxInfo} Message', 'FontWeight', 'bold')
xlabel('Timestamp')
ylabel('Gear')