CAD CAM EDM DRO - Yahoo Group Archive

Re: [CAD_CAM_EDM_DRO] Re: PIC DRO Dreaming

Posted by D.F.S.
on 2000-03-14 08:16:01 UTC
>
> From: stratton@...
>
> > The only issues I can think of right off would be the floating point
> > math, even if nothing more than counting clicks, and multiplying by
> > .00045354, tracking everything to 5 or 6 digits, and rounding it off
> > to provide the current displayed value to .0001 or whatever.
>
> You don't have to do floating point math - simply multiply it by a
> binary fraction large enough to get whatever accuracy you want.
>
> For example, to do 1440 counts/inch and display in thousandths of an
> inch you multiply by 45511 and divide by 65536 or 2^16, which is
> easily accomplished by simply discarding the rightmost two bytes of
> the result. With this approximation, you will be off by 2 parts per
> million, which is far better than the temperature stability of the
> strip, machine, or workpiece. For ten thousandths, use 455111. For
> metric use 115598 and place the decimal point to be consistent with a
> reading in tens of micrometers (10^-5) with an error of 1.9 ppm.

That was why I was a bit iffy on the floating point routines.
I thought there were ways around it, but never had to bother with them.

Thanks.

Marc

Discussion Thread

Paul Devey 2000-03-13 12:39:33 UTC PIC DRO Dreaming D.F.S. 2000-03-13 13:22:04 UTC Re: [CAD_CAM_EDM_DRO] PIC DRO Dreaming stratton@m... 2000-03-13 13:46:18 UTC Re: [CAD_CAM_EDM_DRO] PIC DRO Dreaming William Scalione 2000-03-13 14:19:21 UTC Re: [CAD_CAM_EDM_DRO] PIC DRO Dreaming Paul Devey 2000-03-13 14:20:52 UTC Re: PIC DRO Dreaming Ken Lowther 2000-03-13 14:25:13 UTC Re: [CAD_CAM_EDM_DRO] PIC DRO Dreaming Paul Devey 2000-03-13 14:25:48 UTC Re: [CAD_CAM_EDM_DRO] PIC DRO Dreaming D.F.S. 2000-03-13 15:24:53 UTC Re: [CAD_CAM_EDM_DRO] Re: PIC DRO Dreaming Paul Devey 2000-03-13 16:04:03 UTC RE: [CAD_CAM_EDM_DRO] Re: PIC DRO Dreaming stratton@m... 2000-03-13 17:24:26 UTC Re: [CAD_CAM_EDM_DRO] Re: PIC DRO Dreaming D.F.S. 2000-03-14 08:16:01 UTC Re: [CAD_CAM_EDM_DRO] Re: PIC DRO Dreaming Ian Wright 2000-03-14 08:53:17 UTC Re: [CAD_CAM_EDM_DRO] PIC DRO Dreaming D.F.S. 2000-03-14 09:02:56 UTC Re: [CAD_CAM_EDM_DRO] Re: PIC DRO Dreaming Paul Corner 2000-03-14 14:57:11 UTC Re: [CAD_CAM_EDM_DRO] Re: PIC DRO Dreaming D.F.S. 2000-03-14 15:10:53 UTC Re: [CAD_CAM_EDM_DRO] Re: PIC DRO Dreaming