The problem:
When a user changes the velocity by writing to the VELO field,
but forgets to write to the ACCL field, the acceleration will
change and may be too high.
(Note: Many users are not aware of this side-effect).
Solution:
Introduce a field called ACCS, "Acceleration in seconds^2".
Once the field is written, the ACCL field is updated and the
acceleration is "locked".
It is locked for changes of VELO.
It can be be unlocked by writing to ACCL.
If the acceleration is locked (or not) is stored in the field ACCU,
which can be either "motorACCSused_Accl" or "motorACCSused_Accs".
And in this sense ACCU is not a lock, but just keeps track which
of the accelation fields ACCL or ACCS has been updated last, and
should be used in the next movement.
In any case an update to ACCS updated ACCL and the other way around.
Thanks to Mark Rivers for this nice idea.
Torsten Bögershausen