How to use SCPI to communicate with LibreVNA without opening LibreVNA-GUI

[pishuai1995]

Hello,
I am a little confused, if I write my own script to control LibreVNA, do I have to open LibreVNA-GUI? Currently, I cannot connect to LibreVNA when the Librevna-GUI is not open.

[jankae]

Hi, that is normal. The SCPI server is run by the LibreVNA-GUI. You always have to open the GUI, but you can start it with the "--no-gui" argument which prevents any windows from showing up (but the code for the windows is still running in the background)

[pishuai1995]

Thank you for your prompt reply. Sorry to bother you. I would like to ask, how can I start it with the "--no-gui" argument？

[pishuai1995]

Is this a cmd directive?

[jankae]

Yes, you need to add the argument to the program call on the command line: LibreVNA-GUI --no-gui should do the trick.

[pishuai1995]

Thank you ! I understand.

[ozzyys]

Hello if i start this command "LibreVNA-GUI --no-gui" from my console. It works no problem.

But if i start this command like this from python script, os.system("LibreVNA-GUI --no-gui") the program don't start. So python script also don't make nothing.

[jankae]

I am sure your python script will spit out some kind of error message if it can't start the GUI. This error message will be very helpful here.

In any case, this is my very minimal example to test this:
First, starting the GUI with visible windows:

import os
os.system("./LibreVNA-GUI")

And now with the --no-gui option:

import os
os.system("./LibreVNA-GUI --no-gui")

Both work as intended. The python script is located (and executed) in the same folder as the LibreVNA-GUI executable. Otherwise you might see something like this:

sh: 1: ./LibreVNA-GUI: not found