On Monday 22 June 2015 03:57:06 Steve Stallings wrote:
> Proceed with caution. This board uses slow opto-couplers
> in the data port output signals that are typically set
> up as step and direction outputs. Many users have reported
> problems due to the inability to pass fast signals.
>
> Additionally some variations of this board connect the
> ground on the output sides of the opto couplers to the
> same signal as the ground on the input sides and thus
> do not actually isolate the ground path.

That much is documented.  As for the slow opto's, that doesn't surprise 
me.  While it looks well made, its lack of docs, real docs that spec 
those speeds etc, makes me think its a $3.75 card in Kowloon.

Yesterday I ran stepconf on the normal parport, with my pocket scope 
watching the outputs, and I get good solid direction reversals on 
the "dir" pins, but zip on the step pins.  I suspect that without an 
adjustable reset time, its not going to work even if this box has 
horrible latency, restricting it to a 45u-s base thread or slower.

The docs tend to say both are open collector (OC) and show a pullup.  
This is with a 5v 1 amp supply connected to the 5 & gnd pins, and the 
jumpers on, which commons both grounds and 5 volt lines. I don't think 
the step pulses are wide enough to get thru those opto's, but will get 
out the big scope and check today.

I am in love with the C1G from cnc4pc as it has all these nice pretty 
leds to tell you whats going on, and the opto's are faster than stink 
too, so I guess I'll get me a 3rd one for this machine.

I also see the latest versions of the *542 and *860 drivers can now do 
51200 microsteps, which if combined with the correct currents should be 
able to move steppers as close to silently as they can be moved.

Unforch, while I can probably get steps out of a 5i25 fast enough to get 
decent speeds, the interfaces between them, and likely the opto's in the 
DM542 and DM860 drivers, are not fast enough to take full advantage of 
that.

That is likely one of the things I will do today since I am still waiting 
on the 5i25.  Set up one motor, a 470oz, on the 36v supply that came 
with the kit, and see if the DM542 is faster than the 2M542.  I doubt it 
unless the opto's are lasers.  At 200 per rev, *51200=10,240,000 steps 
per revolution.  As that would be a 1000% step forward in the "state of 
the art", I don't think so.

In my tests with a 2M542 a couple of months back, using a duty cycle 
tweakable function generator, I was able to spin a 425oz motor close to 
3000 revs in the /8 microstep mode, but ran out of opto speeds in the 
2M542 at about 2200 revs (not quite 340 kilohertz at the function 
generator output when trying the /16 step setting.  Most any divisor 
fell over at 330 to 340 kilohertz with the motor stalling silently.

They seem to need a 2 u-sec step, and a 3 to 4 u-sec resting period at 
best.  In this case, they were on & never turned off as the OC voiltage 
stayed within a few millivolts of ground.

Slow opto's on this thing would explain my lack of results.

One question though Steve, I had to put a power supply on it, I thought 
the parport had a 5 volt pin but don't have a pinout handy ATM.  Do I 
have a bad parport?  Or is my memory getting foggy?

> Steve Stallings
>
> > -----Original Message-----
> > From: Gene Heskett [mailto:[email protected]]
> > Sent: Sunday, June 21, 2015 4:56 PM
> > To: [email protected]
> > Subject: [Emc-developers] Next prob, zero docs on the BOB supplied
> >
> > Which is a db25-1205.  Google found it ok, but its a 17 megabyte
> > .exe.
> >
> > Whats the usual linux program to open this winders stuff?
> >
> > Cheers, Gene Heskett
> > --
> > "There are four boxes to be used in defense of liberty:
> >  soap, ballot, jury, and ammo. Please use in that order."
> > -Ed Howdershelt (Author)
> > Genes Web page <http://geneslinuxbox.net:6309/gene>
> >
> > --------------------------------------------------------------
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> > [email protected]
> > https://lists.sourceforge.net/lists/listinfo/emc-developers
>
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Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>

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