Argonne National Laboratory

Experimental Physics and
Industrial Control System

1994  1995  1996  1997  1998  1999  2000  2001  2002  <20032004  2005  2006  2007  2008  2009  2010  2011  2012  2013  2014  2015  2016  2017  2018  2019  Index 1994  1995  1996  1997  1998  1999  2000  2001  2002  <20032004  2005  2006  2007  2008  2009  2010  2011  2012  2013  2014  2015  2016  2017  2018  2019 
<== Date ==> <== Thread ==>

Subject: Motor record bug report
From: Rok.Sabjan@ijs.si
To: sluiter@aps.anl.gov
Cc: tech-talk@aps.anl.gov
Date: Thu, 11 Sep 2003 17:35:18 +0200 (CEST)
Hi!

I have experienced a very subtle bug, which I believe to be a wrong doing
of the motor record. I have seen problems, when moving the stepper motor
with an encoder after VME crate hardware reset (power-down and back up) if
I set the ERES field to a value less than 0.

I use OMS VME58-4E card with an incremental encoder wired to the IO58
board. Everything work very well, but for this problem. Unfortunatelly for
me the wiring has been such that the motor movement direction and encoder
readout direction had different signs. I tried to compensate that with
ERES<0 and everything worked really good.

The problem occurs at hardware reset (as already stated). When I set the
target position (e.g. 1mm) the motor starts but stops much earlier
(typically at around 0.1mm). Subsequent identical commands (go to 1mmm)
move the motor a little further, but it still does not reach the final
position. I ran out of retries as well. This is mended if JOG the motor
just for a bit (direction irrelevant). Once this is done, the motor obeys
commands and moves to the positions I set.

I spent a lot of time debugging the encoder for hardware problems and
nothing helped. But when I set the ERES field back to >0, I couldn't
reproduce this behaviour (the motor went in the wrong direction, of
course). For the final touch, we changed the signal wires of the encoder
(ERES>0) and now everything is as should be.

Some facts:
- this has not occured on software resets
- only little jog solved the problem
- motor record version 4.42 (as seen from medm screen)

Hope this helps you. Please ask for more info, if needed.


Best regards

Rok

Navigate by Date:
Prev: Re: stale data monitor Bob Dalesio
Next: Symb loadable object Geoff Savage
Index: 1994  1995  1996  1997  1998  1999  2000  2001  2002  <20032004  2005  2006  2007  2008  2009  2010  2011  2012  2013  2014  2015  2016  2017  2018  2019 
Navigate by Thread:
Prev: Re: Epics / OS-X Burkhard Kolb
Next: Symb loadable object Geoff Savage
Index: 1994  1995  1996  1997  1998  1999  2000  2001  2002  <20032004  2005  2006  2007  2008  2009  2010  2011  2012  2013  2014  2015  2016  2017  2018  2019 
ANJ, 10 Aug 2010 Valid HTML 4.01! · Home · News · About · Base · Modules · Extensions · Distributions · Download ·
· Search · EPICS V4 · IRMIS · Talk · Bugs · Documents · Links · Licensing ·