Thank you for all answers.
I will use linuxcnc not mach3 because mach3 does not have the ability to make outer close loop (not real time kernel in windows).
The servos are for a lathe retrofit ( x & z axes) and the vfd is to control the spindle speed and direction (cc or ccw)
The servo has a mode position/speed and from an input signal you can select position or speed (step/dir or analog -10 to +10v).
I want to have the ability to override the speed manually outside from gcode so this is the reason why i want analog -10v to +10v.
Also i want to control vfd from gcode to have constant surface speed and i want to override this speed manually.
Because with parallel port hardware limit exits and i can't output 500khz pulse train (2500cpr encoder) i want a card to manage 500khz step/dir signals.
Do you know some card which can do this work in linux and cooperate with linuxcnc ?