More HANDWHEEL

I am having a flue, and lots of sinus pain, difficult to keep my
mind sharp. Sorry. I just thought about what Jon
Elson said again, and I am just going to make a remark:

There is a number of ways to do this, and I guess you could store
your new position as an offset. Maybe use something like the
backlash function. I think a lot depend on the actual machine and
the way you make your programs. I don't know how this would be on a
lathe, or on mill. Maybe you should try to define how you think it
could be implemented on each kind of machine. You could also have a
"user" home, or say that the machine will home in to the position
where you changed reference, then swap back with a predefined feed
rate. You could also have several display output, current and
actual. On the actual machine, it worked as a charm. It was a
plasma cutter, - so no need for tool changes. This had current and
actual position displayed. In a program this would change to
current and next or commanded value - as far as I recall.

Here is something else:

One feature I have seen, - was that each axis would run a predefined
distance. ( a few inches ) Then it would calculate a calibration
value for the DACs. This way each axis had a self calibration
option. I came to think of this, as Dan mentioned the game port
adapter, and temperature changes.

This feature corrected a lot of drifts, and was a handy test of the
machine. You got so used to how the servos should behave, - that you
noticed any changes immediately. It was very nice for trouble
shooting, as well as for doing the calibration.

//ARNE