Using Gecko with Flashcut - was Re: best servo drives

Hi,
I don't have experience using Flashcut with Geckos, but I do have
some testing Flashcut with my Xylotex drives.
First, I found that the 470 ohm resistors shown in the PDF
schematic were not installed. Not a biggie, it's easy to open the
case and find this out. I added my own external resistors to the
test circuit.
Second, under the Motor Signal Setup menu, Signal setup submenu,
there is an option to have the step pulse polarity HIGH or LOW. With
my Logic analyzer set to TTL mode, one setup (I think it was HIGH
pulse, but I don't remeber at this point) would not even trigger the
analyzer (or my board which is the reason I had the analyzer
attached). By changing the polarity (to LOW I beleive), the Logic
analyzer could pick up the signal, and so could the board. I didn't
have a scope hooked up so I don't know what the actual value the
voltages were getting to, but in one case, not enough to trigger the
logic analyzer.
I did see a diagram somewhere on how to replace the DIP optos on
the flashcut board with standard 2N39 type transistors. You lose
opto-isolation at the flashcut side, but if you are using Geckos, you
have that over on the Driver side anyway. This allows more current
drive, which might be just the ticket to get flashcut to work better
with the Geckos (or perhaps Xylotex too, but I didn't try the
transistor method).

Jeff
http://www.xylotex.com


--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Steve Stallings
<stevesng@n...>" <stevesng@n...> wrote:

> Interfacing issues are probably the cause of the
> problems here. Both the Gecko and Flashcut products
> are well respected, but have interface requirements
> that are sometimes not met when connected to other
> equipment.
>
> Gecko drives have a step/direction signal hold time
> requirement that may not be satisfied by the Flashcut
> system.
>
> Flashcut uses opto-isolators in their standard output
> configuration. This would likely cause problems if
> the standard configuration was used with a motor
> driver that also contained opto-isolation of its
> own. This is because opto-isolators are not well
> suited to driving other opto-isolators and signal
> rise time issues result. Some Flashcut users have
> bypassed the internal opto-isolators and reported
> success.
>
> There may also be issues with signal polarity and
> timing being set properly in the Flashcut configuration.
>
> I have been talking to a Flashcut user who is having
> this type of problem and hope to borrow his system
> in an effort to sort out the problems using a
> storage scope. If all goes well I will report on
> the results in a week or so.
>
> Regards,
> Steve Stallings
> www.pmdx.com
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "ironarbor2003
> <Ironarbor@u...>" <Ironarbor@u...> wrote:
> > Ive recently been looking to upgrade frome stepper to servo

motors

> on
> > my plasma table, does any one know wich is the best?
> >
> > Gecko
> > A guy from flash cut called me today and told me that geckos were
> not
> > accurate and that they missed steps? Is this true or a sales man
> > doing his duty to put down everyone else?
> >
> >
> > Rutex
> > Hows shipping, I see that they automatically tune themselves?
> >
> > Any other"lower cost" drives out there?