Re: tach output

Hi,

Three points on this subject.

(1) You can always take the encoder signals back to the PC as well.
The drive uses the encoder to run the motor but that does not mean
you can't send them to the PC as well as a DRO input. You have the
encoder anyway, why not use it if the PC is set up to take the
inputs? It would give a reading even if the drive faults.

(2) The "send a step and hope it gets there" is the same with any
other servo as well. The only reason it wouldn't "get there" is if
the motor was overloaded. At that point the drive is pushing the
motor to 100% capacity. What would any other servo drive do? Find a
way to push it to 101% of capacity? It would also have to fault out
because the motor would have fallen to far behind.

(3) A linear encoder would only work if there is zero backlash. If
there is backlash, the motor will ping pong between the backlash
limits. You can still send the linear encoder back to the PC, and
based on its readings, output the required step / direction signals
to the drive. This takes out leadscrew error as well.

Mariss


--- In CAD_CAM_EDM_DRO@y..., "David Micklethwaite"
<d.micklethwaite@o...> wrote:

> "Jon Elson" <elson@p...> wrote:
>
> >
> > Well, I have a strong preference for real servos. The difference

with the

> > Gecko drives is that the CPU has no position feedback. It sends

step

> > pulses to the Gecko, and hopes it got there.
>
> Is it possible to use a linear encoder of some sort to provide the

feedback

> to the Gecko driver in place of a rotary encoder on the servo motor

shaft? I

> realise that this would still not provide position feedback to the

CPU but

> it might provide some compensation for backlash in the lead screw.
>
> Regards,
>
> Dave.
>