# VOXL2 HITL Sim with Gazebo in Docker - gazebo/voxl2 communication

Source: https://forum.modalai.com/topic/4530/voxl2-hitl-sim-with-gazebo-in-docker-gazebo-voxl2-communication
Category: General Questions (https://forum.modalai.com/category/2/general-questions)
Posted: 2025-06-20 18:56:16 UTC by garret
Replies: 6 · Views: 1115

## garret · 2025-06-20 18:56:16 UTC

Good afternoon, 

I am a new user trying to setup a HITL simulation with gazebo for a standard VTOL. I did the bootcamp from the documentation and then followed VOXL PX4 steps from here: https://docs.modalai.com/voxl-px4/

In short, I get the following when run qshell dsp-hitl status
![f5f79e4d-7937-480f-a284-fcfb3b3e1a04-image.png](https://forum.modalai.com/assets/uploads/files/1750444618289-f5f79e4d-7937-480f-a284-fcfb3b3e1a04-image.png) 

As far as I understand, my J18 port is not receiving data from gazebo. I am using out of the box MCBL-00091-1 USB to Serial UART Cable from ModalAI, so I hope the chord is not an issue. 

Some of the troubleshooting that I have done:

1) checking output from:
    xhost +
    docker run --rm -it --net=host --privileged -e DISPLAY=$DISPLAY -v /dev/input:/dev/input:rw -v /tmp/.X11-unix:/tmp/.X11-unix:ro voxl-gazebo-docker ./run_gazebo.bash
![86af997e-3745-4d72-94b5-d3fb268ec66c-image.png](https://forum.modalai.com/assets/uploads/files/1750444803944-86af997e-3745-4d72-94b5-d3fb268ec66c-image-resized.png) 

Since my /ttyUSB0 is recognized, I assume gazebo is trying to send the data to the voxl2 board.

2) As for my services, I have the following:
![8be9fc25-2000-4e6a-9eae-17811d71df92-image.png](https://forum.modalai.com/assets/uploads/files/1750444876134-8be9fc25-2000-4e6a-9eae-17811d71df92-image.png) 

px4 and qvio are disabled by default and mavlink is running. 

3) trying to adjust latency via:

echo 1 | sudo tee /sys/bus/usb-serial/devices/ttyUSB0/latency_timer

===================================
none of the above produced favorable outcome. I was thinking of trying to set this up via old method in "Archivede instructions" from here: https://docs.modalai.com/voxl2-PX4-hitl/. however, i am using ubuntu 22.04 and as far as I understand gazebo classic is no longer supported on this version. hence, my only option is to use the docker. if anyone has any idea how I can troubleshoot further - it would be much appreciated.

## Reply by garret · 2025-06-20 19:45:42 UTC

@garret Note: this is my physical setup
![Untitled drawing.png](https://forum.modalai.com/assets/uploads/files/1750448734238-untitled-drawing.png)
![Untitled drawing(1).png](https://forum.modalai.com/assets/uploads/files/1750448829160-untitled-drawing-1.png)

## Reply by Eric Katzfey (ModalAI staff) · 2025-06-20 22:14:22 UTC (in reply to garret)

@garret I use the Sparkfun CAB-12977 and CAB-17240 for HITL and it works really well.

## Reply by garret · 2025-06-23 13:14:53 UTC (in reply to Eric Katzfey)

@Eric-Katzfey so you suspect it is a cable issue?

## Reply by Eric Katzfey (ModalAI staff) · 2025-06-23 15:10:59 UTC (in reply to garret)

@garret Very likely. But you also have some errors on gazebo launch that I have never seen before so that could be part of the problem as well.

## Reply by garret · 2025-06-23 16:09:52 UTC (in reply to Eric Katzfey)

@Eric-Katzfey are you referring to libgl errors?

## Reply by garret · 2025-06-23 18:48:12 UTC

RESOLVED

for those who come after:

it was indeed an ftdi cable issue. Keep in mind that MCBL-00091-1 USB to Serial UART Cable is not a proper cable (i tried two freshly out of the box, and none worked). Currently using this cable: https://www.amazon.sa/-/en/Moyina-Converter-Terminated-BeagleBone-Minnowboard/dp/B06ZYPLFNB