Re: Motor record Jog feature

[lavender@sparky.csrri.iit.edu (Bill Lavender)]

> 
> On Tue, 28 Sep 1999, Ron Sluiter wrote:
> 
> > Hello motor record users,
> > 
> > The Jog feature has indeterminate latency.  Hence, we are
> > considering removing it from the motor record.
> > 
> > Do you use it?
> > 
> > Can you use something else?
> > 
> 
> I like the jog button for testing motors, drivers, and encoders.  I just
> tried jogging a motor (using an OMS VME58-8) and did not have a problem
> with soft limits.  The motor record version I'm using is 3.40 with EPICS
> vers. 3.13.0 beta12.
> 
> Kurt
> 
 
Well, currently I am using the jog feature for two different, but
related uses.  One is for powder diffraction, where the users want to
be able to continuously rotate their sample until told to stop so as to
average over the grains in their powder.  At present, the users in
question simply send a command to move the diffractometer phi axis like
'caput s10id:m12.JOGF 1' (wrapped in a shell script) and let the sample
rotate until they tell it to stop.  From testing, I have found that the
version of the motor record I am using does the right thing when the
position counter rolls over and allows the motor to keep rotating.
Thus, for this axis, if I set the soft limits to some huge value, they
are effectively ignored and the motor rotates until told to stop.

I am also using the jog feature in some quick scanning software for XAFS
that I am currently developing where, once again, I tell the motor
controller to move the motor until told to stop after all the scaler
measurements have been taken.

In the case of quick scans, I could probably replace the use of JOGF and
JOGR by commands to move to the current soft limit or commands to move
some long enough distance beyond the end of the expected quick scan
region.  However, for powder diffraction, my users need to be able to tell
the motor controller 'move this motor until I explicitly tell you to stop'.
They will complain mightily if told they can't do this.  The documentation
I have for the version of the motor record that I am using seems to only
give JOGF and JOGR as ways of accomplishing this effect, but if there is
an alternate way of telling the motor to 'move forever', I would be 
interested in hearing about it.

Bill Lavender