Re: [CAD_CAM_EDM_DRO] EMC, Was Re: CAD experiment entry

Jeffrey T. Birt wrote:

>> Another problem with the step/dir approach is you can't ever E-stop the
>> machine without having to rehome. I usually estop my machine whenever I
>> walk away from it, just click a button to bring it back online.
>>
>
>
>
> That sounds more like a 'disable' state than EStop. An Estop system
> generally MUST remove power from the bits that move, that is what it is
> there for.

Yes, and I do. But, if you remove power from a Gecko 320 servo drive,
then the encoder and encoder counter loses power, too, so there is no
longer a comparison between commanded and actual position. When you
power back up, you cannot be sure the machine didn't move any since the
last commanded movement. This is also the same with any stepper system,
if the drives are disabled, the motor can move a few steps due to small
forces in the mechanicals.

> If your servos/steppers/spindle motor/etc still have power applied you are
> NOT in an EStop state. Be safe the life you save may be your own.
>

When I E-stop my machines, the power to the servo amps is interrupted.
But, the power to the
encoders is NOT interrupted, so the computer can continue keeping track
of position.

Jon