motor record

[mooney@aps.anl.gov (Tim Mooney)]

I'd like to modify the way the motor record responds to changes in the
dial-value calibration.  If implemented, this modification could
require changes to BURT backup/restore scripts.

(So everybody knows what I'm talking about here, to change the
dial-value calibration manually, you push the 'Set' button and type in
a new dial value.  This writes the new dial value to the hardware without
moving the motor.)

Currently, changes in user and dial calibration are independent:
changes in .VAL's calibration don't affect .DVAL, and changes in
.DVAL's calibration don't affect .VAL.  As it turns out, this is not
what developers seem to want.  It makes more sense for changes in
.DVAL's calibration to also affect .VAL.  This will make it more convenient
to restore a motor's position after crate power has been recycled, or
an absolute encoder's output has been read, and it will allow client
software to set both user and dial coordinates without having to know
the equation relating them.  Generally, in my experience, if you're
changing .DVAL's calibration, you either want .VAL to follow the change,
or you don't care about it.

The problem with this change is that BURT snapshot files that mention
both .VAL and .DVAL will not work as they used to unless .VAL gets
written *after* .DVAL gets written.  (The BURT snapshot files distributed
on the Software Exchange, in 'xfdApp1_3.12.tar',  write to .VAL first.)
I'd suggest that .VAL not be saved at all, in BURT snapshot files, and
that .OFF and .DVAL be saved instead.

Please let me know if you care about this change one way or another.

Tim