On Wed, Jul 30, 2008 at 01:15:53PM -0400, Sergey Izvoztchikov wrote:
> - is it known to work with EMC2 ?
I don't have personal experience with these boards.
However, reading the TA8435H datasheet I see one thing that concerns me
greatly: fCK (the frequency of the "step" input) is limited to 5kHz
(page 11). In 1/8-step mode, 1.8 degree stepper motor, 20TPI leadscrew,
this limits the speed of rapids to only about 9 inches per minute
even if your motors have enough torque to go faster (in 1/2-step mode
you would be able to get 37.5 inches per minute before hitting the
driver limit)
> Is there EMC2 configuration already available for MDFly CNC system ?
No. However, you can use stepconf to create configuration files for any
"step and direction" system. In stepconf you would enter 1000 ns for
step length ("minimum clock pulse width 1.0 us", page 12). The correct
value for "step space" is 199000 ns, but stepconf won't presently accept
values that big. Instead, you must ensure on each axis page that the
computed value "pulse rate at max speed" is less than 5000Hz (5kHz).
The datasheet doesn't give any values from which "direction setup" and
"direction hold" can be computed, so enter the biggest value accepted,
50000 ns.
> - would be opto-isolated DB25 CNC Brakeout Board a better choice
> with only small increase in cost compare to their 3 axes kit ?
> >From auction info it looks like it'll support up to 6 axles and will
> protect PC circuitry via opto-isolation
Personally, I run without optoisolation -- the 24V motor supply bus I
use is only twice the 12V supply that is already everywhere inside the
PC without isolation. But this is a decision that I wouldn't make for
someone else.
> - are both unipolar and bipolar motors supported or only one of those
> types ?
This depends on the stepper board, not emc. According to the auction
and the datasheet, that stepper board accepts 4 and 6-wire motors (I
don't know why 8-wire motors would not also be supported!) and drives
them in bipolar fashion only.
Jeff
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