Experimental Physics and
Industrial Control System

[email protected] (Hubert Yamada) · Mon, 30 Mar 1998 10:37:42 -1000

-- On Mar 27, 1998, [email protected] (Tim Mooney) wrote
> I should mention that glitches on the limit-switch lines can produce
> very similar behavior, and are by **far** the more common cause of it.
> So don't everybody with an intermittently jerky motor immediately assume
> their hardware is flakey.  You might just need some decoupling capacitors.

I'm not sure that this is true.  I've seen this behavior very regularly
(with the .27 release of the motor record, VME8-8 board).  I don't have
any limit switches in my system and limit-switch support has not been
enabled.

It's been a while since I examined this problem, but it appeared to me
to be a "feature" of the OMS board.  It seems that the OMS board
sometimes returns the wrong motion direction when queried, when it is
first starting to move.  I've tried more than one OMS board, with the
same results, so I doubt that it's due to a hardware problem.

My "solution" was to set the RTRY field to 3.  Obviously, this is a
kludge, and a real solution would be preferable, but it seems to have
eliminated the problem for my purposes.

-- 
Hubert Yamada, University of Hawaii, Institute for Astronomy
 phone: (808) 956-6648                 
e-mail: [email protected]
   WWW: http://ccd.ifa.hawaii.edu/~yamada/

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System