Re: [CAD_CAM_EDM_DRO] Limit and Homing switches

Hi Drew,

Thanks for the comments. If you can't latch the index until read, then
what about a vane or slotted disk, so that you could make the index as
wide as needed? Otherwise, no luck!

A JK F/F can be used to latch the index, and would be reset after being
read.

Alan KM6VV


Drew Rogge wrote:

>
> Hi Alan,
>
> Comments are scattered in your message.
>
> Alan Marconett KM6VV wrote:
> >
> > Hi Drew,
> >
> > You could be right, but as long as you just need the index to happen,
> > and not STAY valid, then it should be OK, IMO.
>
> If the index isn't latched after the step is issued then I'm afraid that
> the controller may not see it.
>
> > I'm not totally clear on
> > this, but essentially you can't "use" the uSteps as INCREASED
> > resolution, just "S M O O T H E R" motion.
> > Are you sure you need the index to stay on (not just the event)? And
> > also, how many encoder "steps" do you have?
>
> The encoders I'm using are 512 counts per rev. So that's 2048 in
> quadrature.
>
> > That has to figure in.
> > Isn't that the STEPS you command with? So I'm thinking you command 5X
> > (encoder) steps, and it moves. So you can stop on one encoder step,
> > right? Or am I all wet? The microstepping should be "inside" these
> > steps? No? Wouldn't you get an encoder step that is 5 microsteps
> > wide? I may not have this right, so we need to get clarification on
> > this!
>
> The G3x0's aren't what I would call a micro stepping drive. In the G320
> and
> G340 in 1X mode the servo turns one quadrature step for each pulse on
> the
> "Step" input. So in my case that would be 1/2048 revs per step. If I
> instead
> jumper the G340 to say 5X mode then the servo turns 5 quadrature steps
> for
> each pulse on the step input from the controller. This would be 5/2048
> revs
> per step or about 410 steps per rev. If as Mariss mentioned in another
> message,
> the index pulse is one line wide and there are, in my case, 512 lines
> per rev
> then it's possible that none of my 410 steps will stop at a point where
> the index pulse is asserted. In 10X mode it takes only ~205 controller
> steps
> per rev and I'm less likely to see the index. I guess if the controller
> is
> polling for the index often enough then it may not miss the index. But
> if for some reason it's not looking when the index goes by then I'm
> SOL.
>
> >
> > I think there is more to a G340 then I understand. Yeah, I KNOW there
> > is! That's why I want to try servos... although I have LOVED playing
> > with stepper motors sense first seeing them in about '77! They spin up
> > pretty fast you say? Humm...
> >
> > Alan KM6VV