Thanks Rempo! I am aware of it, and I was writing about spindle control itself.
If I use a spindle controller that needs 10V Analog for speed control, then what connection is recommended?
(In case later I want to use tapping when it becomes available... here I suppose that tapping / threading is solved by synchronizing feed to the spindle speed+rotation dir.)
1. I use e.g. a MODBUS device with PWM output, and a pwm-analog converter circuit, and feedback spindle index / encoder pulse to the SS
2. I use another step/dir output of the SS, and use a freq-analog converter circuit, and feedback spindle index / encoder pulse to the SS
3. SS already has PWM out? (some kHz)