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PX4 uORB Write

Write uORB data for the specified uORB topic

Add-On Required: This feature requires the UAV Toolbox Support Package for PX4 Autopilots add-on.

  • PX4 uORB Write block

UAV Toolbox Support Package for PX4 Autopilots / PX4 uORB Read and Write Blocks


The PX4 uORB Write block accepts a Simulink® nonvirtual bus that corresponds to the specified uORB topic and publishes the message to the uORB network.

On each sample hit, the block converts the Msg input from a Simulink bus signal to a uORB message and publishes it. The block does not distinguish whether the input is a new message; but, merely publishes it on every sample hit.

During Connected I/O simulation, this block writes data to the peripherals of the hardware.



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To specify the type of uORB message, use the parameter, Topic to Publish to.

Data Types: bus


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Main Tab

Select the name of the uORB topic that the block needs to publish to. Click Select to browse topic names available in the Firmware/msg folder of the px4 directory that you downloaded.

Select the instance of the uORB topic that the block needs needs to publish to.


This parameter appears only if you select a topic that supports multiple instances, in the Topic to publish to parameter.

For example, the actuator_controls topic supports multiple instances and you can select one instance from the drop-down.

Advanced Tab

Enter the maximum number of buffered elements in the publish queue. If the value is 1, no queuing is used to publish the data.

Version History

Introduced in R2018b