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
    ___________    ___    ________    __________    ___________________    ______    ____________    _____    ______

    0.13217 sec    100     false      {0x0 char}    {1x0 uint8        }      0       {0x0 struct}    false    false 
    0.13218 sec    200     false      {0x0 char}    {[            0 0]}      2       {0x0 struct}    false    false 
    0.13221 sec    400     false      {0x0 char}    {[        0 0 0 0]}      4       {0x0 struct}    false    false 
    0.13222 sec    600     false      {0x0 char}    {[    0 0 0 0 0 0]}      6       {0x0 struct}    false    false 
    0.13222 sec    800     false      {0x0 char}    {[0 0 0 0 0 0 0 0]}      8       {0x0 struct}    false    false 
    0.15715 sec    800     false      {0x0 char}    {[1 1 1 1 1 1 1 1]}      8       {0x0 struct}    false    false 
    0.18216 sec    600     false      {0x0 char}    {[    1 1 1 1 1 1]}      6       {0x0 struct}    false    false 
    0.18216 sec    800     false      {0x0 char}    {[1 1 1 1 1 1 1 1]}      8       {0x0 struct}    false    false 
    0.20715 sec    800     false      {0x0 char}    {[1 1 1 1 1 1 1 1]}      8       {0x0 struct}    false    false 
    0.23214 sec    600     false      {0x0 char}    {[    1 1 1 1 1 1]}      6       {0x0 struct}    false    false 
    0.23215 sec    800     false      {0x0 char}    {[1 1 1 1 1 1 1 1]}      8       {0x0 struct}    false    false 
    0.25715 sec    400     false      {0x0 char}    {[        1 1 1 1]}      4       {0x0 struct}    false    false 
    0.25716 sec    800     false      {0x0 char}    {[1 1 1 1 1 1 1 1]}      8       {0x0 struct}    false    false 
    0.28216 sec    600     false      {0x0 char}    {[    1 1 1 1 1 1]}      6       {0x0 struct}    false    false 
    0.28216 sec    800     false      {0x0 char}    {[1 1 1 1 1 1 1 1]}      8       {0x0 struct}    false    false 
    0.30716 sec    800     false      {0x0 char}    {[1 1 1 1 1 1 1 1]}      8       {0x0 struct}    false    false 
    0.33224 sec    600     false      {0x0 char}    {[    2 2 2 2 2 2]}      6       {0x0 struct}    false    false 
    0.33225 sec    800     false      {0x0 char}    {[2 2 2 2 2 2 2 2]}      8       {0x0 struct}    false    false 
    0.35716 sec    800     false      {0x0 char}    {[2 2 2 2 2 2 2 2]}      8       {0x0 struct}    false    false 
    0.38216 sec    200     false      {0x0 char}    {[            2 2]}      2       {0x0 struct}    false    false 
    0.38217 sec    400     false      {0x0 char}    {[        2 2 2 2]}      4       {0x0 struct}    false    false 
    0.38217 sec    600     false      {0x0 char}    {[    2 2 2 2 2 2]}      6       {0x0 struct}    false    false 
    0.38217 sec    800     false      {0x0 char}    {[2 2 2 2 2 2 2 2]}      8       {0x0 struct}    false    false 
    0.40717 sec    800     false      {0x0 char}    {[2 2 2 2 2 2 2 2]}      8       {0x0 struct}    false    false 
    0.4322 sec     600     false      {0x0 char}    {[    2 2 2 2 2 2]}      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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