Re: counting encoder holes ? BEST encoder range ?

Dave,
I'm no expert...but from what I have learned so far, here are the
factors involved that may have an adverse effect by using a high
encoder count:

1. Your choice of controller/software ~ depending on what you are
running, the program can only put out let's say 45,000 pulses per
second. If it has to output 8000 pulses per rev (in quadruture) then
you may hit a wall if it approaches the limit.

2. Your belt reduction ratio ~ if you have a high ratio reduction,
then it may take a lot of pulses from the software to move a
reasonable amount in reasonable amount of time.

3. Your servo driver ~ 2 issues ~ 1. a PID multiplier will
effectively reduce the number of pulses that the software needs to
output. IE- if you use a 4X mult. you would only have to output about
11,000 steps max from software to go the same as the max 45,000
listed earlier (using Mach2 as and example) 2. If running a high
count encoder & Gecko, you may have issues with error counts because
they are so small. In other words, depending on reduction etc, a few
encoder count errors may only total .00001" mechanical error...that's
just too small. You'll pull your hair out! The Rutex has a much
higher error count...but if used with low count encoders, can cause
the servo to hit an axis extent before it stops on it's own.

Hope that helps...as said, I'm no expert...

-Brady

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "turbulatordude"
<dave_mucha@y...> wrote:

>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, Jon Elson <elson@p...>

wrote:

> > turbulatordude wrote:
> >
> > >
> > >The main IC is one I cnnot identify. it is a National Semi, 8

pin

> > >DIP with M8528. I can't seem to cross reference that number.
> > >
> > >
> > 8528 sounds like the date code.
> >
> > >My main interest, of course, is to connect 5v and ground

properly.

> > >
> > >Gnd is (I assume on the ground plane) on pin 4 so I assume pwr

is

> on
> > >pin 8.
> > >
> > >
> > You'd be going out on a limb to make such an assumption. I'd try
> to trace
> > wiring back to obvious power supply connections, perhaps

decoupling

> > capacitors.
> >
> > Jon
>
> I have 4 of these and have not put power to any of them as yet. I
> did trace out to the one capacitor on board and it goes to pin 8.
> With ground on pin 4, I assume it is powered on pin 8 like other

IC's.

>
>
> My next question is...
>
> What is the BEST encoder range ?
>
> I read 800 (200 quadrature) often, but am not sure if that is the
> minimum or optimum.
>
> I have a 2,000 (2,000 quadrature-8,000 pulse) that was advised as

too

> sensitive.
>
> The encoders I have are 500 quadrature, 2,000 pulse.
>
>
> Dave