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

Sun Nov 26 17:37:07 CET 2006

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

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

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*   1. Re: X-Axis Display Problem (David Szakovits)
*   2. Re: X-Axis Display Problem (Paul)
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*----------------------------------------------------------------------
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*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
*>
*>
*>
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*------------------------------
*
*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"
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*
*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.
*
*
*
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