CAD CAM EDM DRO - Yahoo Group Archive

Re: Manual Control

Posted by roboticscnc
on 2005-12-19 07:41:44 UTC
--- In CAD_CAM_EDM_DRO@yahoogroups.com, Stephen Wille Padnos
<spadnos@s...> wrote:
>
> roboticscnc wrote:
>
> >--- In CAD_CAM_EDM_DRO@yahoogroups.com, "James Peck" <jamesgpeck@y...>
> >wrote:
> >
> >
> >>Thanks James, a schematic is exactly what I'm after. What I had in
> >>
> >>
> >mind was somehow converting the quad signal from the encoders to a
> >step / direction signal ( using a switch to select either manual or
> >cnc control ). Maybe there is a simple circuit to do this. This way
> >the computer doesn't have to be switched on. Any information anyone
> >can send me would be greatly appreciated.
> >Thanks, Glen.
> >
> >
> Actually, an encoder is already step/direction, as long as you don't
> spin it too fast (which you can't by hand ;) )
>
> Just connect phase A to the direction input, and phase B to the step
> input. If it runs backwards, switch the two wires.
>
> Here's why it works. This is the pattern of phase signals from an
> encoder (note that they always specify whether it's for clockwise or
> counterclockwise rotation in the datashets):
>
> A B
> 0 0
> 0 1
> 1 1
> 1 0
>
> The stepper drive will only be looking for one edge of the step
signal -
> let's pick the negative-going edge.
> If you apply the sequence above (dir=A, step=B) to the drive, then
it'll
> see a 1 on DIR when the negative step edge appears.
> If you spin it backwards, you get the reverse sequence:
>
> A B
> 1 0
> 1 1
> 0 1
> 0 0
>
> Now, every time the step pulse goes to 0, there's a 0 on the DIR pin.
>
> The disadvantage is that you get only one pulse per full cycle -
there's
> no "resolution multiplication" that we're used to.
>
> Oh - and the speed limit is due to changing the direction line during a
> step. With 1000 CPR encoders, you'd have to spin it at about 12000 RPM
> to have a problem ;)
>
> - Steve
>
Thanks guys, I'll try it out ( after the Christmas rush at work ).
I'll let you know how it goes.
Regards, Glen.

Discussion Thread

roboticscnc 2005-04-13 07:25:12 UTC Manual Control Mike 2005-04-13 08:11:26 UTC Re: Manual Control roboticscnc 2005-12-16 04:50:36 UTC Manual Control roboticscnc 2005-12-18 00:37:12 UTC Manual Control alphawolf45 2005-12-18 05:25:58 UTC Re: Manual Control R Rogers 2005-12-18 07:06:24 UTC Re: [CAD_CAM_EDM_DRO] Manual Control James Peck 2005-12-19 05:04:20 UTC RE: [CAD_CAM_EDM_DRO] Manual Control roboticscnc 2005-12-19 07:05:29 UTC Re: Manual Control Stephen Wille Padnos 2005-12-19 07:22:28 UTC Re: [CAD_CAM_EDM_DRO] Re: Manual Control Derek Brodeur 2005-12-19 07:22:32 UTC Re: Manual Control roboticscnc 2005-12-19 07:41:44 UTC Re: Manual Control vrsculptor 2005-12-19 08:32:08 UTC Re: Manual Control Derek Brodeur 2005-12-19 08:42:03 UTC Re: Manual Control Alan Marconett 2005-12-19 12:28:06 UTC RE: [CAD_CAM_EDM_DRO] Re: Manual Control vrsculptor 2005-12-19 16:09:45 UTC Re: Manual Control roboticscnc 2005-12-27 00:17:13 UTC Re: Manual Control Les Newell 2005-12-27 00:35:59 UTC Re: [CAD_CAM_EDM_DRO] Re: Manual Control roboticscnc 2005-12-27 00:50:13 UTC Re: Manual Control Steve Haushahn 2005-12-27 04:39:20 UTC Re: [CAD_CAM_EDM_DRO] Re: Manual Control Dan Mauch 2005-12-27 08:31:53 UTC Re: [CAD_CAM_EDM_DRO] Re: Manual Control Les Newell 2005-12-28 05:13:12 UTC Re: [CAD_CAM_EDM_DRO] Re: Manual Control roboticscnc 2005-12-28 06:56:35 UTC Re: Manual Control Les Newell 2005-12-28 07:26:32 UTC Re: [CAD_CAM_EDM_DRO] Re: Manual Control