Adjustment of the tubular motor for roller shutters

Good day,

I am having problems with the setting of my roller shutters, which are connected via the bus system. Both run through an actuator. I still don't quite understand why the roller shutters behave the way they do. One actually runs quite nicely. I wanted to adjust the other one now and looked up something on the internet about the endpoints or how to set them. I have not yet hooked up the second roller shutter. Strangely, I can drive the motor down and it then stops with the already functioning roller shutter. Why? Is it because of the actuator? However, I can press the down button several times and each time the roller shutter continues to run down. Shouldn't it eventually stop when the endpoint is reached? Or is it perhaps because the actuator interrupts and then reconnects the power each time the button is pressed??

What exactly do you adjust with these set screws on the roller shutter? Is it only a ratio of the start and end position or do you enter some absolute position? But that is not very likely. Maybe it would shed some light for me if I technically knew what is set with the set screws.

Phew, hope someone can help me :)

Regards Marian

Which bus? Which motor? Which actuator?