Hypersensing with THCAD - better way to do ohmic sensing

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15 Nov 2020 20:53 #189476 by tommylight

See the level I've reached today gives me the opportunity to appreciate things I didn't appreciate years ago. So I think the capabilities of LinuxCNC can make up for Sheetcam's shortcomings.
The point is to start a more lively development and to suppress the feeling of self-satisfaction and superiority of what has been achieved. You still have a lot of work to do.

Please read that again, tomorrow, not today, and let us know the error of that statement.
And not it is not due to translation, if any.
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16 Nov 2020 08:10 #189496 by stivemaster13
What do you mean - the speed of the small holes? Well, it may be well described and I haven't been able to make sense of it yet. I only read it once.

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24 Dec 2020 08:35 #193075 by Creative25
Great info.
I downloaded the firmware for the 7i76e from Mesa. There are mani filed.
The info I am missing is the File name of the firmware. I searched this forum but did not find anything. Which file do I need to load onto the Mesa board?

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24 Dec 2020 09:37 #193077 by rodw

Great info.
I downloaded the firmware for the 7i76e from Mesa. There are mani filed.
The info I am missing is the File name of the firmware. I searched this forum but did not find anything. Which file do I need to load onto the Mesa board?


Use the file ending in pl.bit that suits the 7i76e

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24 Dec 2020 10:21 - 24 Dec 2020 11:01 #193081 by Creative25
Thanks I somehow do not fully understand.

On the Mesa webpage i downloaded the following file.
7i76e.zip

It contains a folder called Config
Inside there is a folder called hotmot2

This folder does not contain a file ending pl.bit

The closest I can find is

7i76e_7i76x1_Dpl.bit

Is this the file I should flash on my mesa card.

Or has the correct file a new name?
Last edit: 24 Dec 2020 11:01 by Creative25.

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24 Dec 2020 14:35 #193116 by PCW
That is the file for a 7I76E for plasma with 3 'A' encoder inputs
to support up 3 THCADs
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23 May 2022 12:29 #243608 by Marçal
Hi! I believe this is the proper thread to post this. As I said in previous posts I don't know much from electronics, so, sorry about that in advance. I am trying to implement a ohmic sensing system and a THC in a 3 axis plasma cutter machine. Before wiring the THCADs everything worked fine. In another thread I created Peter told me it looks like I have a power problem. However, I don't know how to find it. I draw a scheme. I tried to follow the PlasmaC guide, the forum and the Mesa manuals.
I have attached the wiring scheme from the last part, when everything started to fail, plus the report, the ini and hal files. 
I checked the hal code I copied from the plasmaC guide and there are some measurement that I am not sure how to find. They are in bold text:
setp ohmicsense.thcad-0-volt-freq    140200
setp ohmicsense.thcad-max-volt-freq  988300
setp ohmicsense.ohmic-threshold      22.0
setp ohmicsense.ohmic-low            1.0

Can someone help me to find what I am doing wrong, please?
Thank you

 

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23 May 2022 19:23 #243634 by rodw
The frequencies come from the sticker on the THCAD x 1000 (convert kHz to Hz)
The voltages thresholds are where the probe signal turns on (at 22 volts) and off (at 1 volt) in your example
You can watch a probing event in halshow (or use the probe test) to see the maximum voltage in your setup on the ohmicsense.ohmic-volts pin.
The ohmic-threshold needs to be a couple of volts below that voltage.
If your frequencies were wrong and the calculated voltage was below the threshold of 22 volts it will never trigger.

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23 May 2022 19:39 #243636 by rodw
Also you need to connect the 
ohmicsense.ohmic-on pin to plasmac.ohmic-probe and
plasmac.ohmic-enable to ohmicsense.is-probing
There are some lines in your hal that do this that have been commented out.
I think at the time the component was written (before qtplasmac), plasmac wanted you to connect to a debounce pin but I think that has changed.

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31 May 2022 19:41 - 01 Jun 2022 14:07 #244307 by Marçal
Sorry for not answering before, I was struggling with the PlasmaC program and I was trying to make it work before I answer you back. I read PlasmaC was outdated, so I decided to upgrade it to LinuxCNC 2.9 to use QtPlasmaC. I would like to write down one problem I had before I downloaded the QtPlasmaC in case it can help someone: The first time I created the plasmaC connections hal it was empty. I had to create it again and then I got the proper connections.hal file. I could find the frequency thanks to rodw advice. I did not understand what threshold meant. I think now I understand it.

What works on my machine:
-The XYZ is moving and homing
-We can start the Arc and the measuring of the arc voltage is good.

What doesn't work: :-(
-Ohmic probing with THCADWhen the ohmic probing starts the torch goes down, but doesn't measure anything.
We copied your HAL in our custom HAL but it doesn't work. The debounce did not work so we found out we needed to set it up, plus the same with the encoders. The ohmic enable pin makes 24V when our torch touches the metal, the THCAD starts blinking faster and we measure - 24V on that. I checked the ohmicsense.ohmic-volts pin and it does not measure well, it just shows a value of -40.42874 V that does not change, moreover the encoder counter does not work. I wired the THCAD to encoder 4A because I read the velocity is measured in the encoder A and not B. We also added a relay on the Torch on wire because the Hypertherm manual says it needs a dry contact.

I have attached the new electronical scheme.
We have no idea what we are doing wrong, I hope someone can help us to find why it does not measure the ohmic voltage.

Thank you in advance :D
Attachments:
Last edit: 01 Jun 2022 14:07 by Marçal. Reason: I wrote it yesterday night and I wanted to explain more details of what I have done. I also changed the attached files.

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