RE: [CAD_CAM_EDM_DRO] Re: QBasic code for Kulaga/Mauch DRO card

> Tim - I had a thought while looking at your program. I see that
> it writes out a data file. Is this a way to collect say a
> series of scanned points? If this was set up with a contact
> sensing probe in the spindle, could a little variation on your
> software be made to actually reverse engineer or scan a 2 axis
> contour or even a 3D surface?

It could be a starting point, but you would need to develop code to actually
drive a table. This could be done by writing out the parallel port and just
slowly driving the Z axis down until a signal is received back through the
parallel port. Then the program would run the encoder reading routine and
capture the point. The program would then retract the Z axis and move to the
next point and repeat the process. It does seem to me that if you are
setting the program up to drive steppers to move the table you could
dispense with the encoder reading part and just calculate the position from
the steps. The advantage of using the encoders is that lost steps are not an
issue, the disadvantage is increased complexity. I am sure it could be made
to work either way.

> Also if it was written in PB, it would probably work in windows
> too, as PB is almost word for word a super set of QB, or am I
> missing the point that the counts have to be done in realtime and
> Windows won't let you do that?

Actually, it will run just fine in Windows (3.X, 9.X, not NT or 2000) just
fine as is. All you need to do is load the QBasic program if using a 9.X
version as it does not install by default, but it is on the install CD. The
encoders do not have to be read realtime. The way they work is you send a
command to the encoder chip and it latches the data. Then you read the count
as 3 sequential bytes per axis and put it back together. If using 3 axis's
it would probably be better to send the latch command to both encoder chips
one after the other and then go and read the 3 axis's instead of latching
one chip and reading it then latching the other and reading it. Obviously if
you look at the code I am ignoring the 2nd chip for my needs.

OTOH, if it was ported to PB it would probably run faster as I think PB has
the ability to create a compiled .exe I have used QBasic 4.5 which also can
create an .exe and it does increase the execution speed.

Tim
[Denver, CO]

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