How to get data without arming(px4 only connected to PC and GPS)

hi everyone in new to this platform and i try to figure out some staff

1)in the ardupilot interface there was a nub for connection the px4 ,and from that point in time it started to log information (only the px4 without being connected to any drone)
, on the QGC i couldn’t fined this banner ( or couldn’t fined a way that the Px4 started to log information from a point that i commend.
2) when i downloaded the first log (really long one because it was recording from the time that i put the usb port in) i would like to fined a way to open the data in matlab file (like was the option in ardopilot)
any help will be highly would appropriated;


One of the SDLOG parameters allows you to choose when you’re logging. One of them is “from boot…”

thanks for the response
i saw that, but now every log that i want to record i need to disconnect the cable from the usb port, and connect it again (i wanted lazier solution from the program it self but i can handle disconnection cable if this is the case)
thanks a lot again!!!

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@mougly I’m on mobile atm so can’t check but iirc there is a python script to convert from ulog to csv (pyulog?) and from there you can easily import to Matlab the variables you want/need.

Feel free to ping me if you can’t figure it out. I’ll take a look at it if you need

I’m new to phyton , i just downloaded phyton i’m trying to connect it with the code that some one published here but i have a problem im getting an error from matlab with some problem of connecting to python … maybe i saved the log no in some python certain directory?

I think you are taking the wrong approach.

What I did was use Pyulog more precisely the ulog2csv command.

That way you convert your log from ULog format to CSV. Then you have a CSV log and you can easily import this to Matlab.

Hi, thanks now its working finally.
i have a new problem no in the files that i get i couldn’t fined the axis specification , in the log the headers are in 1,2,3 directions and not in Cartesian notation … more over … how the axis specified on the PX4 . The arrow on the boxs is the X direction and the Z axis is straight up? (the Z i assumed is up from the box because the sensor shows me -g in that direction so its make sense.