receive

Wait for new ROS message

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Syntax

msg = receive(sub)
msg = receive(sub,timeout)

Description

example

msg = receive(sub) waits for MATLAB® to receive a topic message from the specified subscriber, sub, and returns it as msg.

example

msg = receive(sub,timeout) specifies in timeout the number of seconds to wait for a message. If a message is not received within the timeout limit, the software produces an error.

Examples

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Open Live Script

Connect to a ROS network. Set up a sample ROS network. The '/scan' topic is being published on the network.

rosinit
Initializing ROS master on http://bat6346glnxa64:33423/.
Initializing global node /matlab_global_node_07536 with NodeURI http://bat6346glnxa64:35561/

exampleHelperROSCreateSampleNetwork

Create a subscriber for the '/scan' topic. Wait for the subscriber to register with the master.

sub = rossubscriber('/scan');
pause(1);

Receive data from the subscriber as a ROS message. Specify a 10-second timeout.

msg2 = receive(sub,10)
msg2 = 
  ROS LaserScan message with properties:

       MessageType: 'sensor_msgs/LaserScan'
            Header: [1x1 Header]
          AngleMin: -0.5216
          AngleMax: 0.5243
    AngleIncrement: 0.0016
     TimeIncrement: 0
          ScanTime: 0.0330
          RangeMin: 0.4500
          RangeMax: 10
            Ranges: [640x1 single]
       Intensities: [0x1 single]

  Use showdetails to show the contents of the message

Shutdown the timers used by sample network.

exampleHelperROSShutDownSampleNetwork

Shut down ROS network. 

rosshutdown
Shutting down global node /matlab_global_node_07536 with NodeURI http://bat6346glnxa64:35561/
Shutting down ROS master on http://bat6346glnxa64:33423/.
Open Live Script

Set up a publisher and subscriber to send and receive a message on a ROS network.

Connect to a ROS network.

rosinit
Initializing ROS master on http://bat6346glnxa64:43469/.
Initializing global node /matlab_global_node_09838 with NodeURI http://bat6346glnxa64:41509/

Create a publisher with a specific topic and message type. You can also return a default message to send using this publisher.

[pub,msg] = rospublisher('position','geometry_msgs/Point');

Modify the message before sending it over the network.

msg.X = 1;
msg.Y = 2;
send(pub,msg);

Create a subscriber and wait for the latest message. Verify the message is the one you sent.

sub = rossubscriber('position')
sub = 
  Subscriber with properties:

        TopicName: '/position'
      MessageType: 'geometry_msgs/Point'
    LatestMessage: [1x1 Point]
       BufferSize: 1
    NewMessageFcn: []


pause(1);
sub.LatestMessage
ans = 
  ROS Point message with properties:

    MessageType: 'geometry_msgs/Point'
              X: 1
              Y: 2
              Z: 0

  Use showdetails to show the contents of the message

Shut down the ROS network.

rosshutdown
Shutting down global node /matlab_global_node_09838 with NodeURI http://bat6346glnxa64:41509/
Shutting down ROS master on http://bat6346glnxa64:43469/.
Open Live Script

Load sample ROS messages including a ROS point cloud message, ptcloud.

exampleHelperROSLoadMessages

Read the 'x' field name available on the point cloud message.

x = readField(ptcloud,'x');

Input Arguments

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ROS subscriber, specified as a Subscriber object handle. You can create the subscriber using rossubscriber.

Timeout for receiving a message, specified as a scalar in seconds.

Output Arguments

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ROS message, returned as a Message object handle.

See Also

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Topics

Introduced in R2019b

ROS Toolbox Documentation
Support