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<== Date ==> <== Thread ==>
Subject: Re: Motion control failure at APS
From: Kurt Goetze <[email protected]>
To: Mark Rivers <[email protected]>
Cc: "Ronald L. Sluiter" <[email protected]>, Emmanuel Mayssat <[email protected]>, EPICS <[email protected]>, [email protected]
Date: Mon, 13 Nov 2006 16:55:31 -0600
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.






References:
RE: Motion control failure at APS Mark Rivers
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