This Small Model shows how to setup Simulink Publishers and Subscribers inside Stateflow in the correct format in order to be able to properly communicate with a ROS Action Server.
In order to use the model, the following steps need to be performed:
1. Move the motion_controller directory into your ROS Catkin Workspace and compile with catkin build or catkin_make.
2. Add the motion_controller messages (motion_controller.action) to the matlab custom messages, using:
https://de.mathworks.com/help/ros/ug/ros-custom-message-support.html
3. Start up the motion_controller robot simulator in a linux terminal or Windows Sub-system for Linux Terminal with:
> rosrun motion_controller motion_controller_test_simulator
4. Start up the motion_controller action server with:
> rosrun motion_controller motion_controller
5. Start the Matlab Simulink Model, and see the robot move through the provided Goals in the workflow.

Note: Presently the waitForServer Command is not working, and is commented out. Anyone who has suggestions on an efficient way to code this is much appreciated.

For an example of using a ROS Action Client alone as a block see:
https://de.mathworks.com/matlabcentral/fileexchange/73602-ros-action-client-block