Another plasma component...

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17 Dec 2018 07:09 #122507 by tommylight
Had a session with it yesterday, using 5i25 stepgens, but could not make it work properly. Need more time.
So far joging works, Y axis does not home, and Z axis does not respond properly to M3 etc.
To be continued......
To do:
Connect the THCAD to have the voltage feedback,
Make all this work with 5i25/7i77 (should be easy afterwards)
Add provisions for changing the cutting current of the plasma cutter ( using relays on older ones or RS485 on new ones, or spindle output for ones that regulate current with a potentiometer ). All this should be automated from the already existing menu PhilC made.
Regards and thank you all,
Tom
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17 Dec 2018 09:39 #122511 by rodw
Replied by rodw on topic Another plasma component...
Tommy, sounds cool. Just some ideas for you. grijalvap has shared some RS485 control code here on the forum somewhere.
If you are going to control amperage with a potentiometer, look at an ACS758 Current sensor. Then a LM358 weak signal amplifier to push it up to around 22 volts off a 24 volt power supply. Then you can read that using one of the Mesa analog inputs. Voila current display on your control system!

The ACS758 comes in various ranges, 50 amp, 100 amp, 200 amp and there are some modules on eBay if you don't want to build your own circuit.

www.ebay.com.au/itm/New-CJMCU-758-ACS758...wT~ZZqTVt:rk:13:pf:0

www.ebay.com.au/p/Lm358-Weak-Signal-Coll...p2047675.m4096.l9055
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17 Dec 2018 10:36 #122513 by andypugh
I think that we should include this component with LinuxCNC, though maybe we need to wait until reverse-run is merged.

However, it is such a "busy" component that I am wondering if this indicates that we need a new "task" component for LinuxCNC.
Currently everything uses "milltask"
linuxcnc.org/docs/html/man/man1/milltask.1.html
github.com/LinuxCNC/linuxcnc/tree/master/src/emc/task

Which sounds like it does "mill things".

However, the man page seems to say that this is entirely a user-space process, so it might not be what one would change to make a dedicated plasma controller, and maybe the HAL component (definitively realtime) is the way to do this.
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17 Dec 2018 11:00 #122514 by rodw
Replied by rodw on topic Another plasma component...
Andy, if you dig through the git in the first post (specifically the axis/plasmac sim) it is clearly a real time component.

from plasmac.hal
#***** PLASMAC COMPONENT ***********************************************
loadrt  plasmac
addf    plasmac     servo-thread

It would be good to get this into the core code and even better if you could help Phill set up a branch in the LinuxCNC git and also his reverse run work so it is in a position to be incorporated.

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17 Dec 2018 11:12 #122515 by andypugh

rodw wrote: Andy, if you dig through the git in the first post (specifically the axis/plasmac sim) it is clearly a real time component..


Yes, plamac is realtime. Milltask is userspace. That was my point.

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17 Dec 2018 11:17 #122516 by rodw
Replied by rodw on topic Another plasma component...
Sorry, I'm a bit lost as to what you are suggesting so I guess others will too. Can you elaborate?

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17 Dec 2018 11:22 #122517 by phillc54
It may be a bit premature for this to be included as I haven't used it on a plasma table yet and I don't know if anyone else has used it either.
I am not sure how much longer before I get my table built.
I am reasonably confident of the operation with all the sim testing I have done but only real world testing will confirm this.
As Rod pointed out in an earlier post the kerf crossing is probably a bit too simplistic but I cannot do much with this until I get my finger out and finish my table.
Cheers, Phill.

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17 Dec 2018 12:37 #122518 by tommylight
@Philc
What would you need to get the machine working ?
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17 Dec 2018 15:27 - 17 Dec 2018 15:30 #122521 by grijalvap
Hi
I have the Hypertherm RS485 python component it has been working good for a long time, unfortunately, I can't post now because I'm far away from the machine but I will do in this week.

I agree PLASMAC component should be included in the LinuxCNC code, I have a very similar one working, so I can test it in a real machine and let you know the results.
Last edit: 17 Dec 2018 15:30 by grijalvap.
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17 Dec 2018 21:58 #122538 by phillc54

tommylight wrote:
@Philc
What would you need to get the machine working ?


I have all the components required so it is just a matter of finding time at the moment.
I retired in June and expected to have plenty of time to do whatever I wanted but that doesn't seem to be the case...

Cheers, Phill.
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