## Built-In Message Support

MATLAB® supports a large library of ROS message types. This topic covers how MATLAB works with ROS Messages by describing message structure, limitations for ROS messages, and supported ROS data types. Refer to the full list of built-in message types at the end of this article.

For information about ROS 2 messages, see Work with Basic ROS 2 Messages.

### ROS Message Structure

In MATLAB, ROS messages are stored as handle objects. Therefore, all the rules of handle objects apply, including copying, modifying, and other performance considerations. For more information on handle objects, see Handle Object Behavior. Each handle points to the object for that specific message, which contains the information relevant to that message type. The message type has a built-in structure for the data it contains.

ROS messages store the data relevant to that message type in a way similar to structure arrays. Each message type has a specific set of properties with their corresponding values that are individually stored and accessed. You can specifically point to and modify each property on its own. The `MessageType` property of each message contains the message type as a character vector. Also, you can use the `showdetails` function to view the contents of the message.

Here is a sample `'geometry_msgs/Point'`, created in MATLAB using `rosmessage`. It contains 3 properties corresponding to a 3-D point in XYZ coordinates.

`pointMsg = rosmessage('geometry_msgs/Point')`
```pointMsg = ROS Point message with properties: MessageType: 'geometry_msgs/Point' X: 0 Y: 0 Z: 0 Use showdetails to show the contents of the message```

You can access and modify each property by using the `pointMsg` handle.

`pointMsg.Y = 2`
```pointMsg = ROS Point message with properties: MessageType: 'geometry_msgs/Point' X: 0 Y: 2 Z: 0 Use showdetails to show the contents of the message```

For more information on the ROS message structure in MATLAB, see Work with Basic ROS Messages.

### Limitations of ROS Messages in MATLAB

Because ROS messages use independent properties, certain messages with multiple values cannot be validated. Because each value can be set separately, the message does not validate the properties as a whole entity. For example, a quaternion message contains w, x, y, and z properties, but the message does not enforce that the quaternion as a whole is valid. When modifying properties, you should ensure you are maintaining the rules required for that message.

Message properties can also have a variety of data types. MATLAB uses the rules set by ROS to determine what these data types are. However, if they are to be used in calculations, you might have to cast the data types to another value. The ROS data types do not convert directly to MATLAB data types. For a detailed list of ROS data types and their MATLAB equivalent, see ROS Data Type Conversions.

### ROS Data Type Conversions

ROS message types have predetermined properties and data types for the values of those properties. These data types must be mapped to MATLAB data types to be used in MATLAB. This table summarizes how ROS data types are converted to MATLAB data types.

ROS Data TypeDescription MATLAB

bool

Boolean / Unsigned 8-bit integer

`logical`

int8

Signed 8-bit integer

`int8`

uint8

Unsigned 8-bit integer

`uint8`

int16

Signed 16-bit integer

`int16`

uint16

Unsigned 16-bit integer

`uint16`

int32

Signed 32-bit integer

`int32`

uint32

Unsigned 32-bit integer

`uint32`

int64

Signed 64-bit integer

`int64`

uint64

Unsigned 64-bit integer

`uint64`

float32

32-bit IEEE floating point

`single`

float64

64-bit IEEE floating point

`double`

string

ASCII string (utf-8 only)

`char`

time

Seconds and nanoseconds as signed 32-bit integers

`Time` object (see `rostime`)

duration

Seconds and nanoseconds as signed 32-bit integers

`Duration` object (see `rosduration`)

### Supported Messages

Here is an alphabetized list of supported ROS packages. A package can contain message types, service types, or action types.

To get a full list of supported message types, call `rosmsg list` in the MATLAB Command Window.

ROS Toolbox supports ROS Indigo and Hydro platforms, but your own ROS installation may have different message versions. To overwrite our current message catalog, you can utilize the ROS Custom Message Support to generate new message definitions.

When specifying message types, input character vectors must match the character vector listed in `rosmsg list` exactly. To use custom message types, MATLAB also provides a custom message support package. For more information, see ROS Custom Message Support.

```ackermann_msgs actionlib actionlib_msgs actionlib_tutorials adhoc_communication app_manager applanix_msgs ar_track_alvar arbotix_msgs ardrone_autonomy asmach_tutorials audio_common_msgs axis_camera base_local_planner baxter_core_msgs baxter_maintenance_msgs bayesian_belief_networks blob bond brics_actuator bride_tutorials bwi_planning bwi_planning_common calibration_msgs capabilities clearpath_base cmvision cob_base_drive_chain cob_camera_sensors cob_footprint_observer cob_grasp_generation cob_kinematics cob_light cob_lookat_action cob_object_detection_msgs cob_perception_msgs cob_phidgets cob_pick_place_action cob_relayboard cob_script_server cob_sound cob_srvs cob_trajectory_controller concert_msgs control_msgs control_toolbox controller_manager_msgs costmap_2d create_node data_vis_msgs designator_integration_msgs diagnostic_msgs dna_extraction_msgs driver_base dynamic_reconfigure dynamic_tf_publisher dynamixel_controllers dynamixel_msgs epos_driver ethercat_hardware ethercat_trigger_controllers ethzasl_icp_mapper explorer face_detector fingertip_pressure frontier_exploration gateway_msgs gazebo_msgs geographic_msgs geometry_msgs gps_common graft graph_msgs grasp_stability_msgs grasping_msgs grizzly_msgs handle_detector hector_mapping hector_nav_msgs hector_uav_msgs hector_worldmodel_msgs household_objects_database_msgs hrpsys_gazebo_msgs humanoid_nav_msgs iai_content_msgs iai_kinematics_msgs iai_pancake_perception_action image_cb_detector image_exposure_msgs image_view2 industrial_msgs interaction_cursor_msgs interactive_marker_proxy interval_intersection jaco_msgs joint_states_settler jsk_footstep_controller jsk_footstep_msgs jsk_gui_msgs jsk_hark_msgs jsk_network_tools jsk_pcl_ros jsk_perception jsk_rviz_plugins jsk_topic_tools keyboard kingfisher_msgs kobuki_msgs kobuki_testsuite laser_assembler laser_cb_detector leap_motion linux_hardware lizi manipulation_msgs map_merger map_msgs map_store mavros microstrain_3dmgx2_imu ml_classifiers mln_robosherlock_msgs mongodb_store mongodb_store_msgs monocam_settler move_base_msgs moveit_msgs moveit_simple_grasps multimaster_msgs_fkie multisense_ros nao_interaction_msgs nao_msgs nav_msgs nav2d_msgs nav2d_navigator nav2d_operator navfn network_monitor_udp nmea_msgs nodelet object_recognition_msgs octomap_msgs p2os_driver pano_ros pcl_msgs pcl_ros pddl_msgs people_msgs play_motion_msgs polled_camera posedetection_msgs pr2_calibration_launch pr2_common_action_msgs pr2_controllers_msgs pr2_gazebo_plugins pr2_gripper_sensor_msgs pr2_mechanism_controllers pr2_mechanism_msgs pr2_msgs pr2_power_board pr2_precise_trajectory pr2_self_test_msgs pr2_tilt_laser_interface program_queue ptu_control qt_tutorials r2_msgs razer_hydra rmp_msgs robot_mechanism_controllers robot_pose_ekf roboteq_msgs robotnik_msgs rocon_app_manager_msgs rocon_service_pair_msgs rocon_std_msgs rosapi rosauth rosbridge_library roscpp roscpp_tutorials roseus rosgraph_msgs rospy_message_converter rospy_tutorials rosruby_tutorials rosserial_arduino rosserial_msgs rovio_shared rtt_ros_msgs s3000_laser saphari_msgs scanning_table_msgs scheduler_msgs schunk_sdh segbot_gui segbot_sensors segbot_simulation_apps segway_rmp sensor_msgs shape_msgs shared_serial sherlock_sim_msgs simple_robot_control smach_msgs sound_play speech_recognition_msgs sr_edc_ethercat_drivers sr_robot_msgs sr_ronex_msgs sr_utilities statistics_msgs std_msgs std_srvs stdr_msgs stereo_msgs stereo_wall_detection tf tf2_msgs theora_image_transport topic_proxy topic_tools trajectory_msgs turtle_actionlib turtlebot_actions turtlebot_calibration turtlebot_msgs turtlesim um6 underwater_sensor_msgs universal_teleop uuid_msgs velodyne_msgs view_controller_msgs visp_camera_calibration visp_hand2eye_calibration visp_tracker visualization_msgs wfov_camera_msgs wge100_camera wifi_ddwrt wireless_msgs yocs_msgs zeroconf_msgs ```