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Transmit and Receive CAN Messages

This example shows you how to use CAN channels to transmit and receive CAN messages. It uses Vector 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('Vector', '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)
  General Settings:
	BusStatus = 'N/A'
	Database = []
	FilterHistory = 'Standard ID Filter: Allow All | Extended ID Filter: Allow All'
	InitializationAccess = 1
	MessageReceivedFcn = []
	MessageReceivedFcnCount = 1
	MessagesAvailable = 0
	MessagesReceived = 0
	MessagesTransmitted = 0
	ReceiveErrorCount = 0
	Running = 0
	SilentMode = 0
	TransmitErrorCount = 0

  Device Settings:
	Device = 'Virtual 1'
	DeviceChannelIndex = 2
	DeviceSerialNumber = 0
	DeviceVendor = 'Vector'

  Transceiver Settings:
	TransceiverName = ''
	TransceiverState = 0

  Bit Timing Settings:
	BusSpeed = 500000
	SJW = 1
	TSEG1 = 4
	TSEG2 = 3
	NumOfSamples = 1

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 2008-2010 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('Vector', '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)
rxMsg = 

  1x406 can.Message handle
  Package: can

  Properties:
    ID
    Extended
    Name
    Database
    Error
    Remote
    Timestamp
    Data
    Signals
    UserData


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

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