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Unfortunately my Herocut plasma gives full arc voltage. I also have a THCAD 300 card to interface with.
It's a possibility what you say. Anyone wishing to give it a go have all the schematics and pcb layouts
as a starter, and all software needed to deliver values over EtherCAT on github.

You know the path isn't always that straight when I develop things. I started with the LAN9252 and it is more or less coincidental that I went with the Ax58100. And you are right, they are used as gateways. In the setup with a MCU I don't really see a difference, can go with any of the two. They are both available on aliexpress and cost about the same. I have gone back to the LAN9252.

For the plasma build, my initial thoughts with EaserCAT-3000 card and the Ax58100 was to use existing stepper motor drivers and have the card do pulse/dir. While that now works, I have skipped that path and are now going to use ECT60 Ethercat stepper motor drives. My own cards will be used for Digital IO (limit switches, float switch, break-away switch, torch on), and for reading the THCAD-300.

Here is the reader for THCAD. A stripped version of the EaserCAT-3000, with LAN9252. The MCU reads PWM frequency on one pin. Could definitely use a smaller MCU, but it is also easy to reuse what I know works.


Digital IO. This card does use the DIO of the LAN9252 directly, no MCU.


I find that the documentation for the Ax58100 is lacking for the special functions, like stepper motor driver. There is a reference application supplied that uses TwinCAT to drive a stepper motor. I guess one could try to understand how all that works, but I haven't. And that is all info I know of.
 

I have never used EtherCAT as in doing a full setup, although i have fixed industrial machines using it i never had to mess with the EtherCAT part, so no idea.
I have used and use a lot of Mesa boards, they are worth every cent/penny/dime as they are extremely reliable and come with the best support on planet earth in the shape of PCW (an active member here), so i will not be switching to EtherCAT ever, especially since i learned it lacks some important stuff for me.
BTW, whatever the price for Mesa is, i have to pay at least double to get them here (black hole named Kosovo), still, i pay it gladly.
Reminds me, have to order some THCAD, installed the last one today.

The other part I always mess up is after installing.

so I’m going to config a machine with 7i76eu + thcad-2 (I think, whatever model the currently have). So I need to configure the system with plasmac

i alway alway forget how to set plasmac on the system.

Yes that one was the default. I just switched to the one Phil provided. Was able to run the materials in QTPlasmac but I seem to have an issue in Height control or maybe it was the consumable guess ill check that real quick...
Ok those look good but I'm getting intermittent raised cuts probably a settings issue in my HC but I've seen some PP create issues there as well. Im using the MESA THCad2 so its more than likely I haven't dialed that in correctly yet.

Thank you guys, I connected before the choke coil, there are 3kV capacitors so the voltage can't be higher than that. I used HV resistors.

Now I'm stucked with the arc voltage.
I placed a 9V battery on the input with a potmeter to test it. I set and calibrrated everything, encoder.0.velocity net to arc-voltage-in, the value changes with the pot but the arc voltage on the GUI and arc-voltage-out signal does not change, stays zero. Tried different scale settings, no result.
How to get that voltage?

Not sure about the analog input of your MESA hardware but it might be possible to use a MESA THCAD board which converts DC voltage to frequency and connects to an encoder input. But you would need to check if it is suitable for 3.3V

'M52 Pn' is Gcode so it would have to go into the Gcode program or be issued as an MDI command.

once you have the voltage (or frequency ) in HAL you can do all kinds of things including a PID loop to control the feedrate also a GUI panel should be trivial then.

forum.linuxcnc.org/plasma-laser/54413-th...-will-kill-it#314239

Hi,
    Has anyone had experience hooking up a CUT55-DS to a MESA THCAD. I contacted Yes Welder, but they gave me the brushoff.
I would like some help if there were any for this model. 

https://www.bing.com/ck/a?!&&p=a103529438c4ea706a21eccd5af2cc56ad07ce8645277c56e1b0e38c5447441fJmltdHM9MTczMTg4ODAwMA&ptn=3&ver=2&hsh=4&fclid=20d478e5-c534-69ce-18ec-6dcbc4c468e8&u=a1L2ltYWdlcy9zZWFyY2g_cT15ZXN3ZWxkZXIrY3V0KzU1LWRzK2JsdWUmaWQ9MDcyOEYzNDM0RkFFMjFDNUEyRUNDRDM4ODg0REUzQTFFMjQ3OUNCNCZGT1JNPUlRRlJCQQ&ntb=1

mesaflash --device 7i92 --addr [card_ip_address] --readhmid

will print the pinout of the currently loaded 7I92 firmware

Great!
just one last silly question: how can i find out to what pins the encoder connects?

i can't find anything about the physical pin numbers in the .ini or .HAL file?
i connected the stepper drivers to wahtever the BOB said and that worked but i feel that this is just luck...
where can i find this?

A CNC4PC C10 (that the OP used) is probably a good choice as its an all 5V BOB.

should i get another bob? and if so what would you recommend?

Unfortunately it would be pretty awkward with those breakouts as the inputs
are slow 12V signals. Even with level shifting I don't know if they could deal
with the ~8KHz signals from the THCAD using the highest divider ratio (128)

The breakout board inputs are activated by grounding so you could try adding
a NPN transistor/small MOSFET to do the level translation from the THCADs ~5V signals
to the 12V required but no guarantees...

A better solution might be to drive the appropriate 7I92 line directly (with maybe a 100 ohm
series resistor for safety)

If you are going to do this (I wouldn't) Make sure your divider resistors are rated for the voltage
and the power. This is difficult as 25KV times 5 mA = 125 W! (this is assuming a THCAD2 jumpered for
5V input and an external 5M resistor)

You can get away with a smaller watt rating because of the "peaky" nature of the HF signal
and it's short duration, but I would not skimp on the voltage rating. I would use  (5x) of
something like this as a minimum:

www.digikey.com/en/products/detail/visha...0001004FAC00/1994729

Because the voltage spikes are mainly in the negative lead,, I would put 4 resistors in the negative lead
and 1 in the positive lead. This combination will (with THCAD2 set for 5V) give a full scale voltage of 255V
 

The proper way would be to wire it to the rectifier output, and use 2 of 1.5Mohm resistors on each wire.
To answer your question, yes HF start can kill the THCAD, but... i have a THCAD10 wired through 2 of 1Mohm resistors at the plasma plugs, plasma is China made Kzubr 60A, it is HF start, it is in use for over 6 months i think, it did not die, yet.
Do this at your own risk, it is not recommended but it works.
Use 2 resistors, 1 on each wire, this is very important, short wires from plasma to resistors, no more than 20-30cm, keep those wires and resistors at least 10cm appart or mount the THCAD close to the source.
And, torch is not positive on plasma, it is negative, the clamp is positive.