Mori MV 35/40 retrofit

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27 Jun 2011 12:22 #10896 by andypugh
Replied by andypugh on topic Re:Mori MV 35/40 retrofit
I think you ought to be able to use (but check with Pete):

1 x 5i23 (not a lot more than the 5i20, and a more spacious FPGA) @ $229
1x 7i33TA @ $79
2x 7i64 @ $198
1x 7i44 RJ45 breakout @ $69
cables @ $100 (but I would make up my own, so nearer $10)

That comes to around $800 but only needs one PCI slot, leaves you with one 5i23 header completely vacant for other cards or IO, and has the option to easily add extra IO in 24+24 blocks as and when you need to.

It needs EMC2 version 2.5, but that is available as a package from the buildbot, and will become the mainstream release fairly soon.

The only drawback is that 7i64 IO runs at servo-thread frequency (1000Hz, typically) rather than base-thread. It would be unusual to run a base thread in a Mesa card config.

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27 Jun 2011 16:48 #10900 by clkeck1
Replied by clkeck1 on topic Re:Mori MV 35/40 retrofit

1 x 5i23 (not a lot more than the 5i20, and a more spacious FPGA) @ $229
1x 7i33TA @ $79
2x 7i64 @ $198
1x 7i44 RJ45 breakout @ $69
cables @ $100 (but I would make up my own, so nearer $10)


That should wrap up the hardware along with a D510MO.

My only question then is the resolver on the spindle motor, that is currently connected to the motor drive, able to be used as an encoder for rigid tap capability?

Thanks
Cory

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27 Jun 2011 18:06 #10901 by PCW
Replied by PCW on topic Re:Mori MV 35/40 retrofit
I doubt that you can share the resolver with the motor drive and a resolver-quadrature converter but I am not sure.
Is there an easy way to add an encoder?

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27 Jun 2011 19:09 #10902 by andypugh
Replied by andypugh on topic Re:Mori MV 35/40 retrofit
PCW wrote:

I doubt that you can share the resolver with the motor drive and a resolver-quadrature converter but I am not sure.


The output impedance of a resolver ought to be quite low, so if the input impedance of the added device is high enough, it should be OK. In any event, as long as it has the same effect on both phases, the angle information should not be affected.

I would be checking to see if there was any position output information from the drive first though.

Not wanting to steal sales from PCW by peddling an inferior device, but you could try using:
wiki.linuxcnc.org/emcinfo.pl?ResolverToQuadratureConverter

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27 Jun 2011 19:47 #10903 by PCW
Replied by PCW on topic Re:Mori MV 35/40 retrofit
I think the problem with sharing a resolver is that both devices want to generate the reference sine as they generate their internal timing from this signal. I suppose a device could generate its internal timing from an external reference sine wave but for example the analog devices sine-quadrature converters do not work this way nor does our 7I49 resolver interface...

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27 Jun 2011 19:54 #10904 by andypugh
Replied by andypugh on topic Re:Mori MV 35/40 retrofit
PCW wrote:

I think the problem with sharing a resolver is that both devices want to generate the reference sine


You are quite right, and I am an idiot. :-)

However, you probably could use some form of simultaneous-sampling A/D to passively measure the voltage.
Possibly an Arduino with an external sample/hold circuit that also converted the AC waveform to an offset DC.

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28 Jun 2011 00:22 #10909 by clkeck1
Replied by clkeck1 on topic Re:Mori MV 35/40 retrofit
Does anyone know what Chris used for a spindle encoder on his mv jr? And does any one know what the drive is doing with the signal besides outputting a speed match signal?

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28 Jun 2011 11:52 #10919 by BigJohnT
Replied by BigJohnT on topic Re:Mori MV 35/40 retrofit
You can ask Chris (cradek) on the IRC he usually is around....

John

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29 Jun 2011 02:56 #10940 by jmelson
Replied by jmelson on topic Re:Mori MV 35/40 retrofit
clkeck1 wrote:

Does anyone know what Chris used for a spindle encoder on his mv jr? And does any one know what the drive is doing with the signal besides outputting a speed match signal?

It was kind of a mess. He bought one of my resolver converters, and the characteristics of the variable reluctance resolver built into the motor were not compatible with my converter. The VR type resolvers need a lot more drive current. He eventually had to remove the resolver and I think fitted an optical encoder in the same place. A small current booster would probably make it work, but it hasn't been tried. (I have the resolver now.)

My resolver converter produces a classic quadrature encoder plus index signal, with 4096 counts/rev,
from a standard 2-pole resolver.

Jon

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06 Jul 2011 16:13 #11187 by schmidtmotorworks
andypugh wrote:

I think you ought to be able to use (but check with Pete):

1 x 5i23 (not a lot more than the 5i20, and a more spacious FPGA) @ $229
1x 7i33TA @ $79
2x 7i64 @ $198
1x 7i44 RJ45 breakout @ $69
cables @ $100 (but I would make up my own, so nearer $10)

That comes to around $800 but only needs one PCI slot, leaves you with one 5i23 header completely vacant for other cards or IO, and has the option to easily add extra IO in 24+24 blocks as and when you need to.

It needs EMC2 version 2.5, but that is available as a package from the buildbot, and will become the mainstream release fairly soon.

The only drawback is that 7i64 IO runs at servo-thread frequency (1000Hz, typically) rather than base-thread. It would be unusual to run a base thread in a Mesa card config.


Thanks for researching and posting the the hardware list, I think I will go with it for my MVJR retrofit, is there anything I should know first?

I'm clueless about the last point about drawback about "base-thread", could you please explain that a little more, I don't understand what it means.

Thanks again for your advice.

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