Re: [CAD_CAM_EDM_DRO] Controlling VFDs from your PC?

Doug Fortune wrote:

> audiomaker2000 wrote:
> >
> > Hi again!
> >
> > Could someone give me a quick rundown on how spindle speeds are
> > controlled from your PC via VFD or Spindle drive?
> > What are the components and what sort of signals are used
> > (step/direction?).
> > I'm getting ahead of myself in this Bridgeport conversion, but down
> > the road it would be nice to have the spindle motor under PC control.
>
> Depends on the VFD, but they might take any of the
> following:
> - analog 0 to 5V
> - analog 0 to 10V
> - analog -10 to +10V
> - digital (serial) control

Some just have a pot from 0-12 V from an internal supply, so they
really don't take an external signal source. Some have 4-20 mA
current loop control. Some have several speeds that can be user-
programmed, and the speeds are selected by a combination of
contact closures.

The isolated analog input would be the best, but this is usually an
extra cost factory option, not field-installable.

If you do have computer control of speed, and in general use on
machine tool spindles, you want to put in the braking resistor, too.

Jon