Thanks for the istructions ;-)
But I'm unshure abouth the cable, guess it's an "Delock Converter USB 2.0 Type-A male to Serial TTL 3.5 mm 3 pin", there is 3.3V and 5.0V. https://www.delock.com/produkte/G_83115/merkmale.html
Is this correct?
And, what voltage?