Re: [Emc-users] Spindle Encoder AEDR-8300 Encoder Ring

[Peter C. Wallace]

On Thu, 29 Nov 2018, Chris Albertson wrote:

Date: Thu, 29 Nov 2018 11:47:23 -0800
From: Chris Albertson <albertson.ch...@gmail.com>
Reply-To: "Enhanced Machine Controller (EMC)"
    <emc-users@lists.sourceforge.net>
To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net>
Subject: Re: [Emc-users] Spindle Encoder AEDR-8300 Encoder Ring
The effective pulse width is always zero if you look at the leading edge.
Pulse length does not matter.

If you care about being the same in each direction then look at the leading
edge when going in the normal direction and if running in reverse look at
the trailing edge of the index pulse.

The quadrature sensor will tell you the direction.  Look at the last data
from the A/B channel to determine direction then decide what index edge to
use.

The worst case is when a person turns the spindle by hand with the motor
powered off and moves the spindle back and forth many times triggering the
index from both directions.   The above should track this well.   But in
real life, you never see this worst case.   But still, it can be handled
with just a few lines of code.


Doesn't need any lines of code, its easily doable in hal, but as I said there 
is no application with normal LinuxCNC spindle sync-ed operations.




On Thu, Nov 29, 2018 at 11:13 AM Peter C. Wallace <p...@mesanet.com> wrote:

On Thu, 29 Nov 2018, David Berndt wrote:

Date: Thu, 29 Nov 2018 12:13:25 -0500
From: David Berndt <ber...@uberwin.com>
Reply-To: "Enhanced Machine Controller (EMC)"
    <emc-users@lists.sourceforge.net>
To: emc-users@lists.sourceforge.net, Peter Blodow <p.blo...@dreki.de>
Subject: Re: [Emc-users] Spindle Encoder AEDR-8300 Encoder Ring

Ok, thanks guys. I'll go with a seperate encoder to pickup a once per
rotation count. Are there any requirements about on/off span in relation
to
A/B. The "centering"  of the index pulse sounds like it could be a bit
fiddly, and getting the pulse perfect would probably be difficult as
well,
presumably linuxcnc won't be comparing A/B to index for any reason, just
needs that index pulse  (+A/B count scaled at 1RPS).

Mesa encoder hardware has the option of gateing index with the quadrature
state but thsi is currently unused

The only disadvantage I see from a wider index pulse is that the index
location would differ in different spindle directions. I dont think there
is
any circumstance in normal LinuxCNC machining operations where this makes
any
difference at all.

Peter Wallace
Mesa Electronics


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--

Chris Albertson
Redondo Beach, California

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Peter Wallace
Mesa Electronics

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