Re: [Emc-users] Serial daisy chain protocol

[Nicklas SB Karlsson]

> > > > > > No SPI over long cable. For long cable RS422 will work, there
> > > > > > is a tradeoff between cable length and speed.
> > > > >
> > > > > Poor wording on my part. I had, once the terminations are
> > > > > sorted, visions of a 3 to 4 foot cable, defined as a long SPI
> > > > > cable.
> > > > >
> > > > > Right now, terms are not well characterized on either end and it
> > > > > takes some loading trickery to make a 6 inch cable work.  Bertho
> > > > > and I spent some time optimizing it to get 30.5 megabit one way,
> > > > > and 25 megabit the other direction.  And its now working well to
> > > > > a Mesa 7i90 with a 1" cable.
> > > >
> > > > Ethernet shielded twisted pair four pairs like this: sck+gnd,
> > > > miso+gnd, mosi+gnd, chip select + gnd. Or flat cable with a gnd
> > > > cable between each of them. Or of course Ethernet if available.
> > >
> > > No, the tcp is too slow, much latency.
> >
> > For TCP resend function to make sense there must be enough time to
> > resend packet.
> >
> > > However, the above scheme, made into ready-made hardware and a
> > > matching rj45 socket signal assignment on those mesa cards that can
> > > support spi, like the 7i90, ...
> >
> > Ethercat chips are available with SPI interface and I concluded then
> > distance is short enough and data is sent between it might be a good
> > choice to skip the Ethercat chips but I might be wrong.
> >
> I'd be for that skip myself, if we had real line drivers in the pi's 
> gpio.  The pi's pin drivers are just barely up to the task, and too 
> fragile electrically for true long term survival if the noise or edge 
> ringing exceeds 4 volts.  Ditto the i/o pins on the 7i90 and its ilk for 
> that matter.

If distance is long enough drivers are required it might be time to switch for 
Ethernet based or CAN.

Nicklas Karlsson

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Re: [Emc-users] Axis -> EMCMOT -> Yaskawa SMC-2000

[Nicklas SB Karlsson]

> >>> I also have Yaskawa drives and motors but planned to replace drive. 
> >>> Encoder is three quadrature signal which is a little bit odd, third 
> >>> usually is zero. I have no time read are comment anything for a day or 
> >>> two.
> >>>
> >>>
> >> I think the scheme (I had some of the old Yaskawa ServPack
> >> drives and motors once) is the C channel looks like A and B,
> >> but the phase relationship between them tells what
> >> electrical quadrant you are in.  So, immediately on
> >> power-up, the drive knows which coils to drive to move the
> >> motor.
> > They are BLDC motors?
> >
> >
> Yes, all the Yaskawa ServoPack motors are 3-phase permanent 
> magnet motors with integral encoders.
> I hate the term BLDC, as they are not DC motors.  But, some 
> people call them that.

I ran them with like PMSM sinusiodal voltages instead of trapezoidal BLDC and 
they seemed to work quite well. I better take a close look at the voltage 
waveforms.

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[Emc-users] Subroutine path

[Eric H. Johnson]

All,

Running lcnc 2.8.0-pre1, SUBROUTINE_PATH in section RS274NGC seems to be 
ignored. If the subroutines are moved to nc_files they run properly regardless 
of the setting of SUBROUTINE_PATH.

This does work at least in version 2.5.4.

Any ideas?

Thanks,
Eric
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