# how to access tflite_data published by voxl_mpa_to_ros from local machine?

Source: https://forum.modalai.com/topic/2388/how-to-access-tflite_data-published-by-voxl_mpa_to_ros-from-local-machine
Category: General Questions (https://forum.modalai.com/category/2/general-questions)
Posted: 2023-07-09 00:25:21 UTC by aashry
Replies: 5 · Views: 1573

## aashry · 2023-07-09 00:25:21 UTC

Hello! 
I'm trying to subscribe to `/tflite_data` publsihed by `voxl_mpa_to_ros` node on my local machine by using `rostopic echo /tflite_data` but I keep getting the following error 
```bash
ERROR: Cannot load message class for [voxl_mpa_to_ros/AiDetection]. Are your messages built?
```
I think this is happening because it's a custom message type that my computer doesn't know about, which means the message definition of `AiDetection` should be integrated somewhere, but I'm not sure what to do. 
The following is a screenshot showing the `voxl_mpa_to_ros` node running on `voxl`, and trying to echo the published topic from a `rosmelodic` docker container, installed onboard on the drone, which shows the same error message that I receive when I try to do that from my local machine as well. Please assist. 

  ![trouble_tflite_data.png](https://forum.modalai.com/assets/uploads/files/1688862287961-trouble_tflite_data.png) 
Thanks in advance for your help!

## Reply by aashry · 2023-07-10 20:08:55 UTC

@aashry If anyone has any insights or suggestions on how to solve this, please do share. Your help would be much appreciated.

## Reply by aashry · 2023-07-11 23:52:00 UTC (in reply to aashry)

@tom can you help me with that, or do you know someone who can help? Thank you so much in advance!

## Reply by tom (ModalAI staff) · 2023-07-12 00:06:06 UTC (in reply to aashry)

@aashry What hardware are you using and what software version are you using?: `voxl-version`

## Reply by jon · 2023-07-13 18:36:22 UTC

@aashry Follow this link: https://gitlab.com/voxl-public/voxl-sdk/utilities/voxl-mpa-to-ros. Catkin_ws -> src -> msg and you will find AiDetection.msg, which you can use to build a ros custom message package (ROS has a tutorial on it I believe). You can do that in whatever workspace you are working in in your docker container. Once that is built and you source devel/setup.bash, you should be able to echo the topic and if you want to subscribe to it in a node you will need to import the message header similarly to any other message type

## Reply by aashry · 2023-07-19 22:48:16 UTC (in reply to tom)

@tom sorry for the late reply, I've been distant from work for one week. I'm using m500 drone with the voxl flight deck. Below is the `voxl-version` output as you requested. I will probably try to follow what @jonathankampia mentioned and see if it works. I will update the thread here accordingly. Thank you guys for your help, appreciate it. 

```bash
--------------------------------------------------------------------------------
system-image: 4.0.0
kernel:       #1 SMP PREEMPT Thu Oct 13 17:57:05 UTC 2022 3.18.71-perf
--------------------------------------------------------------------------------
hw version:   VOXL
--------------------------------------------------------------------------------
voxl-suite:   0.9.4
--------------------------------------------------------------------------------
Packages:
Repo: http://voxl-packages.modalai.com/dists/apq8096/sdk-0.9/binary-arm64/
Last Updated: 1970-01-01 00:05:23
List:
	apq8096-dfs-server       0.3.1
	apq8096-imu-server       1.0.3
	apq8096-libpng           1.6.38-1
	apq8096-system-tweaks    0.1.3
	apq8096-tflite           2.8.3-1
	libapq8096-io            0.6.0
	libmodal-cv              0.2.3
	libmodal-exposure        0.0.7
	libmodal-journal         0.2.1
	libmodal-json            0.4.3
	libmodal-pipe            2.6.0
	libvoxl-cci-direct       0.1.5
	libvoxl-cutils           0.1.1
	voxl-camera-calibration  0.2.3
	voxl-camera-server       1.3.5
	voxl-cpu-monitor         0.3.0
	voxl-docker-support      1.2.4
	voxl-gphoto2-server      0.0.10
	voxl-jpeg-turbo          2.1.3-4
	voxl-libgphoto2          0.0.4
	voxl-libuvc              1.0.7
	voxl-logger              0.3.4
	voxl-mavlink             0.1.0
	voxl-mavlink-server      0.2.0
	voxl-modem               0.16.1
	voxl-mongoose            7.7.0-1
	voxl-mpa-to-ros          0.3.6
	voxl-mpa-tools           0.7.6
	voxl-opencv              4.5.5-1
	voxl-portal              0.4.2
	voxl-qvio-server         0.8.2
	voxl-streamer            0.4.1
	voxl-suite               0.9.4
	voxl-system-image        4.0-r0
	voxl-tag-detector        0.0.4
	voxl-tflite-server       0.3.1
	voxl-utils               1.2.2
	voxl-uvc-server          0.1.3
	voxl-vision-px4          1.4.0
	voxl-vpn                 0.0.6
--------------------------------------------------------------------------------

```