it says it is a “4 CHANNEL 5V 10A RELAY MODULE” sold by ELEGOO
between the 230V netvoltage and the relay is a dc dc converter, which also pulls the voltage down to 24V.
so there is 230V netvolts, which go through two switches to the dc dc converter (24V) and afterwards to the relay… from the other side comes the arduino with 5 and 3.3V. i should be able to choose, with kind of a selector switch, the program… 0 is off, M manual, B flex, T torsion, V vibration. the three state switch (On-Off-On) for relay 1 & 2 is for manual usage and gives the information if relay 3 or 4 is triggert → direction of the engine.
maybe its not the best project to start with, but sadly its my bachelors thesis… so in the end it has to work out