Create the CAN Channels

Create CAN channels for message transmission and reception.

txCh = canChannel("MathWorks", "Virtual 1", 1);
rxCh = canChannel("MathWorks", "Virtual 1", 2);

Open the DBC-file that contains message and signal definitions, and attach it to both CAN channels.

db = canDatabase("CANDatabaseEvent.dbc");
txCh.Database = db;
rxCh.Database = db;

Create the CAN Message

Create CAN message EngineMsg using the database information.

msgEngineMsg = canMessage(db, "EngineMsg")

msgEngineMsg = 
  Message with properties:

   Message Identification
    ProtocolMode: 'CAN'
              ID: 100
        Extended: 0
            Name: 'EngineMsg'

   Data Details
       Timestamp: 0
            Data: [0 0 0 0 0 0 0 0]
         Signals: [1x1 struct]
          Length: 8

   Protocol Flags
           Error: 0
          Remote: 0

   Other Information
        Database: [1x1 can.Database]
        UserData: []

Configure the Message for Event-Based Transmission

To enable a message for event-based transmission, use the transmitEvent command specifying the transmitting channel, the message to register on the channel, and a state value.

transmitEvent(txCh, msgEngineMsg, "On");

Start the Event-Based Transmission

Start the receiving and transmitting channels.

start(rxCh);
start(txCh);

Write new values to the Data property and directly to the VehicleSpeed signal to trigger automatic event-based transmission of the message onto the CAN bus.

msgEngineMsg.Data = [250 100 0 0 20 0 0 0];
pause(1);
msgEngineMsg.Signals.VehicleSpeed = 60;
pause(1);

Stop the transmitting and receiving channels.

stop(txCh);
stop(rxCh);

Analyze the Behavior of Event-Based Transmission

The receiving channel now has two messages available, corresponding to the two updates that resulted in two transmissions.

rxCh.MessagesAvailable

ans = 2

Receive the available messages. Inspect the messages and note that each has the data values set previously to the Data property.

msgRx = receive(rxCh, Inf, "OutputFormat", "timetable")

msgRx=2×8 timetable
        Time        ID     Extended        Name                   Data              Length      Signals       Error    Remote
    ____________    ___    ________    _____________    ________________________    ______    ____________    _____    ______

    0.032835 sec    100     false      {'EngineMsg'}    {[250 100 0 0 20 0 0 0]}      8       {1x1 struct}    false    false 
    1.0606 sec      100     false      {'EngineMsg'}    {[250 100 0 0 60 0 0 0]}      8       {1x1 struct}    false    false 

Inspect the signals and note that the second instance of VehicleSpeed has the data value set previously to the VehicleSpeed signal.

signals = canSignalTimetable(msgRx)

signals=2×2 timetable
        Time        VehicleSpeed    EngineRPM
    ____________    ____________    _________

    0.032835 sec         20           2835   
    1.0606 sec           60           2835   

View Messages Configured for Event-Based Transmission

To see messages configured on the transmitting channel for automatic transmission, use the transmitConfiguration command.

transmitConfiguration(txCh)

Periodic Messages

None


Event Messages

ID  Extended   Name            Data         
--- -------- --------- ---------------------
100 false    EngineMsg 250 100 0 0 60 0 0 0

Close the Channels and DBC-File

Close access to the channels and the DBC-file by clearing their variables from the workspace.

clear rxCh txCh
clear db