Blank Message

R2026b

Create blank ROS 2 message using specified message type

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Blank Message ROS 2 block

To add a block to a model, double-click the canvas and start typing the block name. Then, select the block from the list.

Libraries:
ROS Toolbox / ROS 2

Description

The Blank Message block creates a Simulink^® nonvirtual bus corresponding to the selected ROS message type. The block creates ROS message buses that work with Publish, Subscribe, Call Service and Send Action Goal blocks.

Examples

Call ROS 2 Service in Simulink

Call a service on the ROS 2 network in Simulink using the Call Service block and receive a response.

• Open Live Script

Ports

Output

Msg — Blank ROS 2 message

non-virtual bus

Blank ROS 2 message, returned as a non-virtual bus. To specify the type of ROS message, use the Type parameter. All elements of the bus are initialized to 0. The lengths of the variable-length arrays are also initialized to 0.

Data Types: bus

Parameters

Class — Class of ROS 2 message

Message (default) | Service Request | Service Response | Action Goal | Action Feedback | Action Result

Class of ROS 2 message, specified as Message, Service Request, Service Response, Action Goal, Action Feedback and Action Result.

For basic publishing and subscribing, use the Message class. To create a service request message for Call Service input, use the Service Request class. To create an action goal message for Goal input of Send Action Goal, use the Action Goal class. You can use the Action Feedback or Action Result classes to create an action feedback message or action result message of specific type respectively.

Message type — ROS 2 message type

'geometry_msgs/Point' (default) | character vector | dialog box selection

ROS 2 message type, specified as a character vector or a dialog box selection. Use Select to select from a list of supported ROS messages. The list of messages given depends on the Class of message you select.

Sample time — Interval between outputs

Inf (default) | positive numeric scalar

Interval between outputs, specified as a numeric scalar. The default value indicates that the block output never changes. Using this value speeds simulation by eliminating the need to recompute the block output. Otherwise, the block outputs a new blank message at each interval of Sample time.

For more information, see Specify Sample Time (Simulink).

Programmatic Use: Add Block

To add the block programmatically, use the add_block function with one of these library block paths as the source.

"ros2lib/Blank Message"

Example: add_block("ros2lib/Blank Message","myModel/myBlock",MakeNameUnique="on")

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2019b