OMS VME-8 motor controllers:

[sullivan@oxygen.aps1.anl.gov (Joseph P. Sullivan)]

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From mooney Fri Jun 10 12:30:12 1994
To: sullivan@oxygen.aps1.anl.gov
Subject: Re: OMS VME-8 motor controllers:  PAL upgrades
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Joe, re...

> re...
> > I spoke with Steve Flego at OMS this morning (I called to get rev B of the PAL).
> > He is currently working on rev C, which modifies the interrupt acknowledge
> > timing slighty (~50nsec).  He is looking for some customers to test out rev C
> > with the MVME167's.  If anyone is considering modifying the driver code to
> > run in an interrupt driven rather than polling mode, Steve would be very
> > interested in working together to test the new PAL.  The phone number at
> > OMS is 503-629-8081.
> 
> Currently the OMS boards must be polled in order to provide dynamic motor 
> position readback. This would make using the 'operation complete' 
> interrupt redundant. The (as yet unavailable) OMS VME58 controller places
> the current motor position in dual ported RAM. The driver for this board
> could make effective use of the interrupt capability.

The current VME8 can generate an interrupt when a programmed sequence
of commands has completed, and the interrupt routine can get the same
information the polling routine gets, right?  The difficulty with
completely polled operation is that the polling rate (currently 10 Hz)
is the fastest rate at which data points can be acquired.  Although
some motors can make a small move and settle in a few msec, as we use
it the VME8 can't report 'done' in less than 100 msec.  If we increased
the polling rate to 60 Hz (max. for the VxWorks watchdog timer),
message traffic from a single motor in motion would use up 50% of the
CPU.  It would be nice to have 5Hz polling and quick response to small
moves.

Tim


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