# px4 params flow to autopilot

Source: https://forum.modalai.com/topic/3949/px4-params-flow-to-autopilot
Category: VOXL SDK and Software (https://forum.modalai.com/category/47/voxl-sdk-and-software)
Tags: mpa
Posted: 2024-11-17 15:36:42 UTC by jacob yaacubov
Replies: 1 · Views: 1868

## jacob yaacubov · 2024-11-17 15:36:42 UTC

on the voxl2 qrb5165 there is this folder 
/data/px4/param

holding the PX4  parameters and calibration 

sometimes at bootup the QGC says all parameters lost 
seems that on each flight those params are being modified 

I want to solve this issue of calibration &  params loss  by the px4  
I will appreciate a short explanation of how the voxl-px4-params data is flowing on the device 
my guess is params shall be set and saved via QGC later the VOXL will pull them from the autopilot on each flight to /data/px4/params is this the case ? 

thank you !

## Reply by Zachary Lowell 0 · 2024-11-18 14:11:20 UTC

@jacob-yaacubov said in [px4 params flow to autopilot](/post/19752):
> sometimes at bootup the QGC says all parameters lost
> 

Hi Jacob - Unsure if I am fully following but this is the explanation for how parameters work on the voxl2:

Every boot of the voxl2 kick off the px4 instance if you have that service enabled - it will then grab the parameters from /data/px4/param (if a parameter file already exists) - if you save a file from QGC of edit a parameter, from their, it will update in this file as well. As for why the parameters are lost - I am assuming what you mean is the parameter file isnt fully loaded (AKA the green bar at the top of qgc never finishes because of a timeout) - if that is the case I would recommend trying another qgc instance on a different device like a phone or different os (mac vs linux vs windows) - and see if the problem persists.

Zach