[Bdi4emc-help] RE:X-Axis Display Problems

Sun Nov 26 18:09:18 CET 2006

On Sunday 26 November 2006 11:37, elnerdo at cox.net wrote:
>Thanks for the help, guys.
>
>20,000 counts per revolution is in fact pretty high for an encoder. The
> "latest thing" however is the new sin/cos encoders which output counts
> in the millions.
>
>http://www.engineeringtalk.com/news/enc/enc109.html

Just one comment here.  Nice, but where do we hide, and get power for, the 
Cray SX1 it will take to do the a/d conversions and transcendentals of 
this things output in anything even remotely resembling real time?  
Particularly at its full speed of 12,000 rpm.

Methinks this is a solution looking for a problem.

>I originally thought the video card might be the problem source so I
> replaced it last week (and lowered the period to .0001) but the problem
> still remains.
>
>My next step is to make an attempt at recompiling without the debounce
> code.  I have *some programming experience but a duffer's guide on this
> would be great!  Really, any instructions or recommended reading you
> could suggest would be appreciated.
>
>Regards,
>
>Craig
>
>
>*-----Original Message-----
>*From: bdi4emc-help-bounces at lists.ourproject.org [mailto:bdi4emc-help-
> *bounces at lists.ourproject.org] On Behalf Of bdi4emc-help-
> *request at lists.ourproject.org *Sent: Friday, November 24, 2006 3:00 AM
>*To: bdi4emc-help at lists.ourproject.org
>*Subject: Bdi4emc-help Digest, Vol 10, Issue 4
>*
>*Send Bdi4emc-help mailing list submissions to
>*	bdi4emc-help at lists.ourproject.org
>*
>*To subscribe or unsubscribe via the World Wide Web, visit
>*	https://lists.ourproject.org/cgi-bin/mailman/listinfo/bdi4emc-help
>*or, via email, send a message with subject or body 'help' to
>*	bdi4emc-help-request at lists.ourproject.org
>*
>*You can reach the person managing the list at
>*	bdi4emc-help-owner at lists.ourproject.org
>*
>*When replying, please edit your Subject line so it is more specific
> *than "Re: Contents of Bdi4emc-help digest..." *
>*
>*Today's Topics:
>*
>*   1. Re: X-Axis Display Problem (David Szakovits)
>*   2. Re: X-Axis Display Problem (Paul)
>*
>*
>*----------------------------------------------------------------------
>*
>*Message: 1
>*Date: Thu, 23 Nov 2006 11:43:13 -0500
>*From: David Szakovits <dszakovits at cfl.rr.com>
>*Subject: Re: [Bdi4emc-help] X-Axis Display Problem
>*To: "Help and advice for BDI-4 users."
>*	<bdi4emc-help at lists.ourproject.org>
>*Message-ID: <4565CFA1.8070607 at cfl.rr.com>
>*Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>*
>*i am not sure that i am not seeing the same sort of thing.  i
> definitely *get some freezing. i have been warned about the on board
> video that i *have and i am going to buy an AGP card to see if that
> might fix the *symptom but being a emc-novice, i do not know what to
> expect or if it *will fix the problem or if at all related. *djs
>*
>*Craig Gadd wrote:
>*
>*>Hello Paul,
>*>
>*>I'm having a problem with my BDI setup and was hoping that you might
> have *>some advice on a problem I have.  I'm running BDI 4.51 with a
> Motenc Lite *>Card installed.  The card is connected through a 50 pin
> ribbon cable to a *>Vital Systems breakout board which in turn has been
> wired to a single *>encoder which has 20,000 quad/cts per revolution).
> *>
>*>When I launch the generic.run, or emc.run things seem to behave
> normally *>with the units showing for the axis which has the encoder on
> it.  The *units *>will update if I turn the motor slowly, and
> everything seems to work. *When
>*>I spin the motor quickly however, the unit display of the axis seems
> to *>"freeze" and will not recover.  The rest of the interface
> continues to *>function properly though.  Any ideas on what might cause
> this and how I *>might fix it?  I've tried Tkemc,Xemc, and mini but
> they all seem to behave *>the same. *>
>*>Thanks,
>*>
>*>Craig
>*>
>*>
>*>
>*>_______________________________________________
>*>Bdi4emc-help mailing list
>*>Bdi4emc-help at lists.ourproject.org
>*>https://lists.ourproject.org/cgi-bin/mailman/listinfo/bdi4emc-help
>*>
>*>
>*>
>*
>*
>*
>*------------------------------
>*
>*Message: 2
>*Date: Thu, 23 Nov 2006 17:51:41 +0000
>*From: Paul <bdi4emc at bulldoghome.com>
>*Subject: Re: [Bdi4emc-help] X-Axis Display Problem
>*To: bdi4emc-help at lists.ourproject.org
>*Message-ID: <200611231751.41344.bdi4emc at bulldoghome.com>
>*Content-Type: text/plain;  charset="iso-8859-1"
>*
>*
>*Hi Craig
>*
>*On Thursday 23 November 2006 06:52, Craig Gadd wrote:
>*> The card is connected through a 50 pin ribbon cable to a *> Vital
> Systems breakout board which in turn has been wired to a single *>
> encoder which has 20,000 quad/cts per revolution). *
>*That is a pretty high resolution encoder !
>*
>*> When I launch the generic.run, or emc.run things seem to behave
> normally *> with the units showing for the axis which has the encoder
> on it.  The *units *> will update if I turn the motor slowly, and
> everything seems to work. *When
>*> I spin the motor quickly however, the unit display of the axis seems
> to *> "freeze" and will not recover.  The rest of the interface
> continues to *> function properly though.  Any ideas on what might
> cause this and how I *> might fix it? *
>*Many years ago, Fred Proctor (as I recall) was having problems with
> erratic *encoder counts and added a routine to "debounce" the input -
> This is hard *coded with an arbitrary limit of 10 times the max
> velocity. When the rate *of *change per servo cycle ecceeds this limit,
> any further input is ignored and *a *following error *should be
> triggered. *
>*With a 20,000 count/rev encoder and a moderate max velocity, I would
> *imagine *it would be quite easy to trigger the debounce routine - When
> you come to *connect the servo amps up and tune the system, as long as
> you don't go over *the top on the acceleration settings, you shouldn't
> experience any *problems.. *If you do, we can disable the debounce
> routine easily enough by *adding -DSIMULATED_MOTORS to the RTFLAGS of
> src/Makefile.inc.in and *recompiling vitalmod.ko *
>*If you need a step by step duffer's guide to setting up a build
> environment *and recompiling the kernel modules, just ask. *
>*
>*BTW With any servo system there is nothing to be gained by setting the
> *BASE_PERIOD parameter anywhere near what you might use with a stepper
> *system. *0.00005 or 0.0001 should be fine.
>*
>*
>*Regards, Paul.
>*
>*
>*
>*------------------------------
>*
>*_______________________________________________
>*Bdi4emc-help mailing list
>*Bdi4emc-help at lists.ourproject.org
>*https://lists.ourproject.org/cgi-bin/mailman/listinfo/bdi4emc-help
>*
>*
>*End of Bdi4emc-help Digest, Vol 10, Issue 4
>********************************************
>
>
>_______________________________________________
>Bdi4emc-help mailing list
>Bdi4emc-help at lists.ourproject.org
>https://lists.ourproject.org/cgi-bin/mailman/listinfo/bdi4emc-help

-- 
Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Yahoo.com and AOL/TW attorneys please note, additions to the above
message by Gene Heskett are:
Copyright 2006 by Maurice Eugene Heskett, all rights reserved.