Re: [CAD_CAM_EDM_DRO] Re: emc help

On Saturday 31 January 2004 01:07, Greg wrote:

> -
> Hello,
> Whoever wrote this doesnt know much about encoders.
> I use hiedhain encoders and they are expensive but they have a max
> encoder freq of 300khz which is double the normal spec of most other
> encoders.

well, you cant have looked very far ... most go to *at least* 10mhz or so ...
are you *sure* you know the diference between pulse rate and ppr?

> The only exception to this i have found is laser encoders made by
> canon.(Way to expensive)

see above

> Also if you check your specs on the STG board the max enoder freq is
> not 10 mhz but much lower.

not sure that is correct either ...

> And of course the parallel port could not run at these speed.

no, but you would not use a paralell port directly to read the encoders,
you'd use the paralell port to read a register that was constantly updated by
the encoders, that way the paralell port only needs to run at servo loop rate
(10 khz or so) which it can do easily ...

> And even the pico systems is limited to 300khz
>
> Regards,
> Greg
>
> -- In CAD_CAM_EDM_DRO@yahoogroups.com, Ray Henry <rehenry@u...> wrote:
> > > From: Jon Elson <elson@p...>
> >
> > <s>
> >
> > > Most encoder counters can handle 300,000 to 1 million encoder
> > > counts/second. So, that would be 30 to 100 inches a second, or
>
> 1800 to
>
> > > 6000 IPM. Is that enough for you?
> >
> > STG claims 10 MHz.. In theory you can multiply these values by 10
>
> so you
>
> > could be dealing in miles per minute.
> >
> > Ray
>
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