Quote Originally Posted by vre View Post
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 ?
I think you're still confusing analogue servo operation with step/direction.

You can use the servo
a) with analogue voltage control and encoder feedback for closed loop positioning OR
b) with step/direction pulse train open loop or closed loop with encoder feedback

You can't use step/direction AND analogue voltage together, they are different operating modes of the servo amplifier/driver. A CSMIO/IP motion control card will do what you need and works with Mach3 (it does closed loop control outside of Mach3), don't know about LinuxCNC: the CSMIO/IP-S will do step/direction, the CSMIO/IP-A will do +/-10v analogue. Both will provide the spindle VFD speed/direction output.