Transmit and Receive CAN Messages

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This example shows you how to use CAN channels to transmit and receive CAN messages. It uses MathWorks Virtual CAN channels connected in a loopback configuration.

Create a Receiving Channel

Create a CAN channel to receive messages by specifying the vendor name, device name, and device channel index.

rxCh = canChannel('MathWorks', 'Virtual 1', 2);

Inspect the Channel

Use the get command to obtain more detailed information on all of the channel's properties and their current values.

get(rxCh)

        ArbitrationBusSpeed: []
               DataBusSpeed: []
          ReceiveErrorCount: 0
         TransmitErrorCount: 0
       InitializationAccess: 1
           InitialTimestamp: [0x0 datetime]
                 SilentMode: 0
           TransceiverState: 'N/A'
                   BusSpeed: 500000
               NumOfSamples: []
                        SJW: []
                      TSEG1: []
                      TSEG2: []
                  BusStatus: 'N/A'
            TransceiverName: 'N/A'
                   Database: []
         MessageReceivedFcn: []
    MessageReceivedFcnCount: 1
                   UserData: []
              FilterHistory: 'Standard ID Filter: Allow All | Extended ID Filter: Allow All'
           MessagesReceived: 0
        MessagesTransmitted: 0
                    Running: 0
                     Device: 'Virtual 1'
         DeviceChannelIndex: 2
         DeviceSerialNumber: 0
               DeviceVendor: 'MathWorks'
               ProtocolMode: 'CAN'
          MessagesAvailable: 0

Start the Channel

Use the start command to set the channel online.

start(rxCh);

Transmit Messages

The example function generateMsgs creates CAN messages and transmits them at various periodic rates. It creates traffic on the CAN bus for example purposes and is not part of the Vehicle Network Toolbox™.

type generateMsgs

function generateMsgs()
% generateMsgs Creates and transmits CAN messages for demo purposes.
%
%   generateMsgs periodically transmits multiple CAN messages at various
%   periodic rates with changing message data.
%

% Copyright 2008-2016 The MathWorks, Inc.

    % Create the messages to send using the canMessage function. The 
    % identifier, an indication of standard or extended type, and the data
    % length is given for each message.
    msgTx100 = canMessage(100, false, 0);
    msgTx200 = canMessage(200, false, 2);
    msgTx400 = canMessage(400, false, 4);
    msgTx600 = canMessage(600, false, 6);
    msgTx800 = canMessage(800, false, 8); 

    % Create a CAN channel on which to transmit.
    txCh = canChannel('MathWorks', 'Virtual 1', 1);

    % Register each message on the channel at a specified periodic rate.
    transmitPeriodic(txCh, msgTx100, 'On', 0.500);
    transmitPeriodic(txCh, msgTx200, 'On', 0.250);
    transmitPeriodic(txCh, msgTx400, 'On', 0.125);
    transmitPeriodic(txCh, msgTx600, 'On', 0.050);
    transmitPeriodic(txCh, msgTx800, 'On', 0.025);
    
    % Start the CAN channel.
    start(txCh);
    
    % Run for several seconds incrementing the message data regularly.
    for ii = 1:50
        % Increment the message data bytes.
        msgTx200.Data = msgTx200.Data + 1;
        msgTx400.Data = msgTx400.Data + 1;
        msgTx600.Data = msgTx600.Data + 1;
        msgTx800.Data = msgTx800.Data + 1;
        
        % Wait for a time period.
        pause(0.100);
    end

    % Stop the CAN channel.
    stop(txCh);
end

Run the generateMsgs function to transmit messages for the example.

generateMsgs();

Receive Messages

Once generateMsgs completes, receive all of the available messages from the channel.

rxMsg = receive(rxCh, Inf, 'OutputFormat', 'timetable');
rxMsg(1:25, :)

ans =

  25x8 timetable

        Time         ID     Extended       Name          Data        Length      Signals       Error    Remote
    _____________    ___    ________    __________    ___________    ______    ____________    _____    ______

    0.0019373 sec    100     false      {0x0 char}    {1x0 uint8}      0       {0x0 struct}    false    false 
    0.0019488 sec    200     false      {0x0 char}    {1x2 uint8}      2       {0x0 struct}    false    false 
    0.0019744 sec    400     false      {0x0 char}    {1x4 uint8}      4       {0x0 struct}    false    false 
    0.0019827 sec    600     false      {0x0 char}    {1x6 uint8}      6       {0x0 struct}    false    false 
    0.0019863 sec    800     false      {0x0 char}    {1x8 uint8}      8       {0x0 struct}    false    false 
    0.025069 sec     800     false      {0x0 char}    {1x8 uint8}      8       {0x0 struct}    false    false 
    0.051911 sec     600     false      {0x0 char}    {1x6 uint8}      6       {0x0 struct}    false    false 
    0.051914 sec     800     false      {0x0 char}    {1x8 uint8}      8       {0x0 struct}    false    false 
    0.076913 sec     800     false      {0x0 char}    {1x8 uint8}      8       {0x0 struct}    false    false 
    0.10191 sec      600     false      {0x0 char}    {1x6 uint8}      6       {0x0 struct}    false    false 
    0.10191 sec      800     false      {0x0 char}    {1x8 uint8}      8       {0x0 struct}    false    false 
    0.12691 sec      400     false      {0x0 char}    {1x4 uint8}      4       {0x0 struct}    false    false 
    0.12691 sec      800     false      {0x0 char}    {1x8 uint8}      8       {0x0 struct}    false    false 
    0.15191 sec      600     false      {0x0 char}    {1x6 uint8}      6       {0x0 struct}    false    false 
    0.15191 sec      800     false      {0x0 char}    {1x8 uint8}      8       {0x0 struct}    false    false 
    0.17691 sec      800     false      {0x0 char}    {1x8 uint8}      8       {0x0 struct}    false    false 
    0.20191 sec      600     false      {0x0 char}    {1x6 uint8}      6       {0x0 struct}    false    false 
    0.20198 sec      800     false      {0x0 char}    {1x8 uint8}      8       {0x0 struct}    false    false 
    0.22691 sec      800     false      {0x0 char}    {1x8 uint8}      8       {0x0 struct}    false    false 
    0.25192 sec      200     false      {0x0 char}    {1x2 uint8}      2       {0x0 struct}    false    false 
    0.25192 sec      400     false      {0x0 char}    {1x4 uint8}      4       {0x0 struct}    false    false 
    0.25193 sec      600     false      {0x0 char}    {1x6 uint8}      6       {0x0 struct}    false    false 
    0.25193 sec      800     false      {0x0 char}    {1x8 uint8}      8       {0x0 struct}    false    false 
    0.27693 sec      800     false      {0x0 char}    {1x8 uint8}      8       {0x0 struct}    false    false 
    0.30193 sec      600     false      {0x0 char}    {1x6 uint8}      6       {0x0 struct}    false    false

Stop the Channel

Use the stop command to set the channel offline.

stop(rxCh);

Analyze Received Messages

MATLAB® provides a powerful environment for performing analysis on CAN messages. The plot command can create a scatter plot with message Timestamps and identifiers to provide an overview of when certain messages occurred on the network.

plot(rxMsg.Time, rxMsg.ID, 'x')
ylim([0 2047])
xlabel('Timestamp')
ylabel('CAN Identifier')

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