Hello everybody,

I just ran the latency test and the jitter of the servo thread was 800,000
ns!!!. Hopefully the machine is only used to position the grinding wheel
joint and the part joint, one axis at the time. I've never tried using the
parport to run the steppers, it was directly connected with the mesa 5i20.

As happened with Kirk, I think the latency increased with the upgrade to
ubuntu 10.04, since there was no latency error before, but I don't remember
quite well when the error started. I think I will try installing a video
card and then see what happens with the latency.

Unfortunately most of the new motherboards come with 1 pci connector, and
industrial range motherboards are very expensive. It's getting hard to find
suitable motherboards with enough pci connectors, because it's good to have
at least two to use a parport card.

I need to start looking for this, because the next machine that we are
planning to build is a 4 axis mill to make rough cutting of camshaft lobes,
and with this latency results I really doubt that the trajectory planner
could handle 3 axis at the time.

Thank you guys as always for your good help!

Leonardo.

2011/10/31 John Thornton <[email protected]>

> You will only get the message once per session even if you have latency
> problems all day long...
>
> John
>
> On 10/30/2011 6:53 PM, Leonardo Marsaglia wrote:
> > I have the same behaviour on a machine running steppers even with a mesa
> > 5i20 for the step generation. The problem anyway shows everytime I start
> > EMC, then it doesn't appear  all day long until the machine is turned
> off.
> >
> > I think it's a problem with my motherboard or processor. But, I remember
> > the problem not appearing when I use any other configuration, or even
> when
> > my present machine configuration was not so old and touched, since I've
> > been adding and trying things out.
> >
> > Anyway I hope my problem could help to fix yours!
> >
> > Regards.
> >
> > Leonardo.
> >
> > 2011/10/30 andy pugh<[email protected]>
> >
> >> On 30 October 2011 20:59,<[email protected]>  wrote:
> >>> Occasionally I get the "Unexpected real time error" that ruins a piece
> >> I don't think it is all that usual for a latency error to ruin the
> >> workpiece. Do the steppers stall when it happens, or something?
> >>
> >>> If I understand there are PCI MESA devices that will replace my buitlin
> >> parallel port
> >>> Will this solve the "Unexpected real time error"
> >> Maybe. Hardware step generation is likely to be a lot more reliable.
> >> What sort of stepper drives are you using?
> >>
> >> --
> >> atp
> >> "Torque wrenches are for the obedience of fools and the guidance of wise
> >> men"
> >>
> >>
> >>
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