When you try to deploy a Simulink model created using UAV Toolbox Support Package for PX4® Autopilots to the selected Pixhawk® Series flight controller using the USB cable, a pop-up dialog box appears with the instruction to disconnect and reconnect the flight controller. The deployment of the model may not happen even though you click OK in that dialog box.
To resolve the issue:
Ensure that you click OK within 5 seconds after disconnecting and reconnecting the USB cable connected between the host computer and the Pixhawk Series flight controller.
The 5-seconds limit applies only to the time after reconnection. Therefore, you can first disconnect the USB port from the host computer without worrying about the time limit; but, ensure that you click OK within 5 seconds after reconnecting the cable to the USB port of the host computer.
After you click OK, verify the progress in the Diagnostic Viewer in Simulink. The Diagnostic Viewer displays the following lines that indicate the start of a successful deployment.
If you do not see the progress of deployment in the Diagnostic Viewer (as shown in the above image), try the process again (disconnect and reconnect the USB cable), and then click OK within 5 seconds.