Re: [CAD_CAM_EDM_DRO] EMC as DRO?

Raymond Heckert wrote:

>My understanding is that the 'DRO' numbers you see on EMC's screen are
>generated by the program, corresponding to the signals 'sent' *to* the
>driver... not signals 'received' *from* the encoders. The driver is s'posed
>to make sure the servo (or stepper) has moved to the 'correct' position.
>.. But, I've been wrong before...
>
>

If you have real encoders on the machine (either rotary or linear) and these
feed back to the computer through some sort of interface, then these numbers
can be EITHER the commanded or the actual, measured, position. Some people
keep the display on commanded, because the flickering of digits on the
actual position display bothers them. You switch between these two modes
with the @ key, and a mark on the screen shows what mode that display is in.
Of course, if you don't have encoders at all, or your encoders only feed
back
to a step/dir driver like the Gecko 320, then the "actual" position
display is
a phoney, of course.

On any EMC system where encoders feed back to the computer, the actual
position is being read by the computer and used to calculate velocity for
the most accurate moves, even if you are not displaying the actual position
on the screen.

When I put my servo system in "manual" mode, and then move the machine
by hand, the numbers track that movement, and I can then go back to CNC
mode, and the correct axis alignment is kept.

Jon