Can't publish message from Simulink to ROS

I am having trouble sending a message from Simulink to a ROS. The ROS master is running on a separate laptop which runs ROS kinetic on Ubuntu 16.04. When I echo the ROS topic on this laptop the message appears empty. The simulink model and empty message is attached below. Any help is much appreciated.

Answer 1

[Abhijeet Gadkari]

Hello Ben,

sensor_msgs/Joy is a ROS message that contains variable sized sub-messages.

There is a documented example for working with ROS messages of variable sizes from Simulink.

As shown in the Modify maximum Size of Variable-length Array section of that example, you need to set the correct array-size of the Axes and Buttons fields for sensors_msgs/Joy.

In above snapshot, I've updated the Simulink model with 'Probe Width' blocks and assigned the width to CurrentLength field. In PuTTy window, echo of /joy topic shows message published from MATLAB.

-Abhijeet

[Ben Locke]

Hi Abhijeet

Thank you for your response, the model now works.

Best regards

Ben

[Nupur]

Hi @Abhijeet Gadkari I want to publsih ros2 message trajectory_msgs/JointTrajectoryPoint with positions [x1...xn, y1....yn] at each time step for example at time(t1) publish [x1...xn,y1...yn], at time(t2) publish [x1...xn, y1...yn] and so on.

I tried your solution for my task however, as the positons with size [128*2] i am getting erros. I have attached the file. Thanks in advance.