@o_lampe
Yes, you are right, my g-code is wrong, i only tried to show idea that for continues rotation distance does not matter, you need only speed and direction.
seem the most correct way will use new M code for that purpose for example:
Mxxx Xnnn; start to rotate axis X with speed xxx (non blocking command!)
Mxxx A-600; rotate axis A (setup A as continuesly rotation in config) with speed 600 counter-clockwise