Re: [CAD_CAM_EDM_DRO] BDI with DRO/Encoder Board

David Kryskowski wrote:

>
> I compiled the latest version from linuxcnc.org. dro.h and dro.c had to be updated from the latest fixes at sourceforge. The install script is much improved and made life much easier. Running with smdromod.o is much slower than using the original BDI code.

I think you turned down the P term to 5 to make the double-servo loop stable. You
will have to turn it back up for single servo.

> I am not sure what the problem is. It is really unusable when using the tk interface. The xwin interface is somewhat better and the mouse somewhat follows your hand movement. I did compare the .ini files and the timing parameters were the same. Could be compile optimizations but have not looked into it.

Oh, you are talking about CPU time available for non-RT tasks. If you are running out of
CPU resources, you need to reduce the RT load. If using one of the freqmod derivatives
(not sure whether smdromod.o is or isn't) then the PERIOD parameter can be made larger
to reduce the number of times a second that the pulse generating code is scheduled.
Default is 16 uS, which is pretty heavy!

> Our machinist and I will be using the computer control for the first time tomorrow. We went over the interface together today and it seems pretty simple.
>
> Finally since I can't use smdromod.o for week what is the best motordriver to use for my appication? Is it stepmod.o or freqmod.o? I have seen the new ppm code that you wrote at sourceforge (pulse position modulation?). Should we give that a go?

Are you talking about PPMC? That requires my special hardware, and for now is servo
only. I have demonstrated a stepper rate generator version of this, but it is not quite
ready, yet. I'm fighting problems integrating the digital I/O with the rest of it.
PPMC stands for Parallel Port Motion Control.

Otherwise, stepmod.o gives best steps/second performance on a given CPU.
But, if you have resonance or lost steps problems with it, then freqmod.o gives a
much smoother step pulse stream, which allows the motors to follow better.
It depends to some extent on the motors and stepper drivers used.

Jon