Re: Interesting Xylotek stepper problem

["Lee & Chris studley" <indigo_red-at-qwest.net>]

Hi,
This is a similar problem with in timing incompatibility with the 
GeckoDrives especially with the PLL step multiplier.

I think a user definable timing setup should be included in a apropos 
section in the ini file. It should include a
setup and post step hold time for the direction signal with respect ot the 
step active edge. Also polarity definition
of the step and direction would be helpful.

-Lee


At 12:56 PM 4/15/03 -0400, you wrote:


>List
>
>Recently I was playing with a Sherline minimill with those laser engraved
>handwheels right on the motors and found an interesting problem with the
>Xylotek stepper driver cards.
>
>Steppermod causes a motor to move the direction it was going for one pulse
>after a direction change.  In the eternal scheme of things it will never be
>more than one step or microstep off and it always corrects itself after the
>next direction change.  It is just a bit disconcerting to watch the Sherline
>handwheel take a wrong step when you press the 0.0001 jog button.
>
>A recent post from Jeff Pollard, Xylotek's wizard says;
>
> > If you look at PDF page 3 in my datasheet at:
>
> > http://www.xylotex.com/XS35V.pdf
>
> > you can see the timing diagram of how the STEP/DIR signals need to be.  The
> > DIR line needs to be stable 200 ns BEFORE and AFTER the RISING edge of the
> > STEP signal.
>
> > Is is possible that you are using a FALLING edge to trigger the STEP
> > signal.  This would most likely be the case if you were used to using
> > Geckos that require a FALLING signal (which allows their optoisolator to
> > fire).
>
>Freqmod is fine with this.  Matt tells me that is because there is a one
>motion loop delay after a direction change.
>
>What are the possible fixes here?
>
>Ray