Experimental Physics and
Industrial Control System

"Reinhard Pahl" <[email protected]> · Mon, 13 Nov 2006 17:03:03 -0600

Kurt:  We had the same problem at BioCARS (APS) and fixed it in the same
way. It's a cheap fix, it works - and that's what really matters.

-Reinhard.

-----Original Message-----
From: Kurt Goetze [mailto:[email protected]] 
Sent: Monday, November 13, 2006 4:56 PM
To: Mark Rivers
Cc: Ronald L. Sluiter; Emmanuel Mayssat; EPICS;
[email protected]
Subject: Re: Motion control failure at APS

The only times we've had spurious limit switch problems that the
transition
board capacitors didn't solve were due to exceptionally noisy
chopper-type
microstepper drivers.  For this I designed a custom socket for the OMS
VME58
limit switch pals that puts caps right on the limit switch sense pins.  
Not pretty
but it works.

Kurt

Mark Rivers wrote:
> The transition cards that the APS BCDA group built to connect the
> OMS58/MAXv and the ACS Step-Pak drivers have on-board de-glitching
> capacitors.  These increase the time constant on the limit switch
lines
> so that we never see problems, even with very long lines from the
> controller to the driver.
>
> This is generally a simple and cheap solution.
>
> Mark
>  
>
>   
>> -----Original Message-----
>> From: Ronald L. Sluiter [mailto:[email protected]] 
>> Sent: Monday, November 13, 2006 2:15 PM
>> To: Emmanuel Mayssat
>> Cc: EPICS
>> Subject: Re: Motion control failure at APS
>>
>> The OMS VME58 is susceptible to noise on the limit switch lines.
>> This has been the most frequent problem that I have been called on
>> the diagnose.
>>
>> Kurt Goetze and I did some testing to see if this is a 
>> problem with the
>> MAXv.  Of course we can't quantify it, but it appears that OMS has
>> done a much better job with the MAXv on this issue.
>>
>> Ron
>>
>> Emmanuel Mayssat wrote:
>>
>>     
>>> I actually had the exact opposite problem.
>>> My motor controller would barely start a move.
>>> The limit switches were reported as not closed, and the 
>>>       
>> apparatus was in
>>     
>>> a safe position to operate. The problem was due to glitches 
>>>       
>> on the limit
>>     
>>> switch cables (we actually never observed those glitches). 
>>>       
>> The problem
>>     
>>> was reproducible in a controlled environment (engineering bench). 
>>> As of today, we think it was due to cable length and cross talking.
>>> We rebuild and shortened the cables. It immediately worked.
>>>
>>> Food for thoughts and... time for lunch,
>>>
>>> --
>>> Emmanuel
>>>
>>> On Mon, 2006-11-13 at 12:56 -0600, Mark Rivers wrote:
>>>  
>>>
>>>       
>>>> Folks,
>>>>
>>>> We have seen failures in the past where a motor moved 
>>>>         
>> constantly at a
>>     
>>>> slow rate right past limit switches on an OMS58.  It 
>>>>         
>> happened only on a
>>     
>>>> single axis, not on all 8 axes.
>>>>    
>>>>
>>>>         
>>>  
>>>
>>>       
>>
>>     

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System