Hi,
I'm trying to read the midi values of the knobs on my keyboard when I start pd. At the moment I have to move every single knob first.
Is there any chance to do this?

it depends on your keyboard.

you'd need to send some message from pd TO the keyboard, to tell it to dump all its current knob positions. What message that is, or if it's even possible will depend on the keyboard, not pd.

read the keyboard's documentation and find out.

It's a cheap evolution mk-225C. There's nothing written down in the documentation about this... so maybe it's not possible?