Encoders

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13 Feb 2020 21:27 #157324 by PCW
Replied by PCW on topic Encoders
The base thread period would typically be set in your ini file

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14 Feb 2020 08:51 #157338 by machinedude
Replied by machinedude on topic Encoders
i was like a deer caught in the headlights looking through all the pictures of this build :) i started something like this but it's been sitting for a while since i got distracted with another build i am working on. DMM has some nice Servo's and drives in the DYN4 range. i went all servo for mine with 4 of them with the 4th as a spindle motor except i went with the 750 watt motors since the RPM was 5,000 on the ratings. i was told by DMM that they will actually do 6,000 RPM on 230V. 1.8 kw could be geared up by running at a 2 to 1 ratio but the HP would end up only being around 1.5 hp by doing so.

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14 Feb 2020 09:56 #157341 by rodw
Replied by rodw on topic Encoders

PCW wrote: No, but you could add an external RC filter on a 7I96 isolated output
or use a fancier board like the 7I76E that has a buillt-in analog spindle
interface

You can also try setting all this up with your parallel ports. This will limit your
maximum speed, but the tuning and scaling issues are basically the same
regardless of what hardware interface you use.


Peter, so now i'm confused. What I think I'm hearing is a 7i96 is not really a good choice for a milling machine unless say you use MODBUS for spindle control so the 7i76e would be a better match. And you'd still need to use the 7i85/7i85s to manage the encoders.

It seems every time I turn around, you release a new board... :)

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14 Feb 2020 10:39 #157344 by Clive S
Replied by Clive S on topic Encoders

It seems every time I turn around, you release a new board... :)

Rod I don't think the 7i96 was available when your built your plasma.

The 7i96 is a fantastic board but does not have spindle control. I have used 3 of these including one on my plasma. I have also used one on a Warco mill without spindle control but you could use a simple cheapo BOB the one with the blue relay on, and stick it on the expansion port for the spindle control.
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14 Feb 2020 15:42 #157362 by natholego11
Replied by natholego11 on topic Encoders
so I get it. using the Mesa system is the best route and one I will take when the time comes. but for now...

what is the process for setting up encoders with a second paraport in terms of identifying the base thread, setting up the encoders in the HAL file, and tuning the system to not have tons of jitter while trying to hold a position?

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14 Feb 2020 16:25 #157365 by andypugh
Replied by andypugh on topic Encoders
If adding a second parport you would use the same base thread for parport.1.read as you are already using for parport.0.read

So, where is says "addf parport.0.read base-thread" you would append "addf parport.1.read base-thread"

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14 Feb 2020 20:19 #157373 by rodw
Replied by rodw on topic Encoders

Clive S wrote:

It seems every time I turn around, you release a new board... :)

Rod I don't think the 7i96 was available when your built your plasma.

The 7i96 is a fantastic board but does not have spindle control. I have used 3 of these including one on my plasma. I have also used one on a Warco mill without spindle control but you could use a simple cheapo BOB the one with the blue relay on, and stick it on the expansion port for the spindle control.


Yes that right, the 7i96 is quite new. So while it has the advantage of inbuilt relays, it only has one expansion connector, no spindle control and no MPG inputs. Using a BOB for spindle control makes no sense if he can't connect it to the Mesa ethernet card becasue he needs a 7i85 to read his encoders

So in this case where the OP needs a spindle and a 7i85 for encoders, he really should use the 7i76e. The 7i85 or 7i85s will still work with it and he will still have one expansion connector free.

So in summary, the 7i76e will give him a lot more I/O ports (32 inputs, 16 outputs, full spindle control, 2 MPG inputs, a couple of analog ports).

I kinda think we've made his decision harder than it needed to be. The only question is should he use the active high 7i76e I have or the newer active low 7i76eD which may make it a bit simpler to wire up given he has existing wiring.

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14 Feb 2020 20:22 #157374 by rodw
Replied by rodw on topic Encoders
And here is Norbert's amazing connection sheet for the 7i76e
forum.linuxcnc.org/27-driver-boards/3191...-sheet?start=0#85072

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14 Feb 2020 20:28 - 14 Feb 2020 20:51 #157375 by PCW
Replied by PCW on topic Encoders
Note that the 7I96 does have 4 channels of MPG inputs with the proper firmware
(though any used as MPGs subtract from the 11 isolated inputs)
Last edit: 14 Feb 2020 20:51 by PCW.
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14 Feb 2020 21:57 #157377 by tommylight
Replied by tommylight on topic Encoders
If i am not mistaken, the expansion port on any mesa card can be used to read encoders, at very fast rate.

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