Re: ethernet flaky with servos?

[Steve White <steve.white-at-lomar.com>]

Group,

    I've been lurking & learning for some time, but I think I might be able to
offer some help here with this one.
    I just happen to have a bunch of Cabletron 10BaseT to 10BaseFL transceivers
unused still in boxes that I would be willing to sell cheap if anyone in the
group wants to use them for noise isolation.  I know they work - they're new and
I've used several of them, but you'll still have a short segment of CAT5 between
your NIC and the transceiver that might be susceptible to noise.  As long as the
wall transformer that powers the transceiver is plugged in to the same place as
the EMC computer, I think you would achieve noise immunity.  Connecting two of
these back-to-back through a patch cable might be a good cheap way to get the
isolation and noise immunity you need without having to replace the existing NIC
and switch with fiber units.
    I don't have an EMC set up and running on a real CNC machine yet, but I have
used several of these transceivers on my network here at home (including a P166
BDI machine) to provide electrical isolation on the underground connection
between house and pole barn after losing a hub and a NIC to a lightning strike a
while back.
    If anyone is interested, you can email me directly.

Thank you,
Steve

Pete Cook wrote:

> I have some related expirience - I work for a company that build plasma &
> oxy/Fuel cutting machines - We use a 3com 10baseFL fiber NIC for the same
> reason - One customer thought they knew better and tried to use 10baseT
> instead and watched their whole network turn to molasses. You might check
> the grounding of all components in you system. Ground the machine, the
> motors, all encoder cables to an outside ground rod. What may be happening
> is that there is enough noise generated and the only ground path is through
> the computer and thus everything attached to that computer is also having to
> deal with noise. Also check the routing of all your cables and make sure
> that the motor cables (including the AC Supply) are run seperate from any
> computer connected cabling. We have also had serial ports on the computer
> used to download programs to the cutting machine damaged - we switched to
> fiberoptic modems to isolate the serial ports on the cutting machine and
> computer.
>
> Pete Cook
>
> PS - if you are using PWM type drives they are extremely noisy and need
> extremely good grounding and isolation.
> >
> > Hello All -
> > I have a difficult that's not quite on the main topic
> > of this list.
> >   When my motors are on and holding position,
> > my local ethernet segment goes to heck.  Not just the
> > test machine, but everything attached to the switch.  When
> > the motors are on, but idling, I see some network errors, but
> > it is still usable.  I have a linksys 8-port workgroup switch
> > and UTP cat5 cabling.  The motors have no load - bench
> > system - and the drives and motors are in a steel shelf.
> > Would STP cabling or gobs of shielding be useful?
> > Has anyone had similar experiences?
> > Thank you.  --krb
> >
> >
> >
> >