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thank you for the information Rod. mine has an hpr 130 torch on it and it uses technical gases while cutting, it is dual shielded. the probing happnens from the outer shield on wich the copper consumable touches the table and completes the loop with the ground cable. the wire for probing is connected to the outer shield itself, i can send a picture tomorrow if needed. i'll order two THCAD boards. how would i proceed to connect the one used for probing to the Mesa 7i97T? is it the same as voltage sensing? connected to an encoder input?

If you use shielded tips so the bare electrode does not connect the material, I would use a second THCAD for material probing.
ONe user here stated it was crazy fast and saved a lot of time...

Hi everyone, i have an industrial cnc plasma table made by CR Electronic on wich the numerical contol has stopped working and i would like to try and retrofit it with linux cnc and QTPlasmaC interface..
it has 3 axis for the usual X,Y,Z movements and then an additional axis named "K" that is basically a slave to the X axis. it is a tray connected to the air extraction/filtration system that travels underneath the table to catch all the sparks and fumes made when cutting.
it has servomotors on all axis with analog/digital drives controlled with  +/-10V

i have a few question that i'd like to ask before getting started with the retrofit:

What board should buy?
since it has the analog drives i think the ideal board for this retrofit would be the the Mesa 7i97T  combined with a THCAD2 for the THC control.
the plasma currently has a proprietary board wich handled the thc control and the Z axis motion. also it has ohmic sensing and torch breakaway detection. the voltage signal comes from the plasma generator wich is a Hypertherm HD3070 and outputs direct plasma voltage to the thc control, so i'll have to put a high voltage resistor prior to the THCAD2 board.

Do i need 1 or 2 THCAD2 board?
i've read multiple topics about retrofits on cnc plasma tables on the forum but can't figure out if i need to get 1 or 2 boards to combine with the 7i97T Board. can the 7i97T take the input from the plasma voltage to control the THC? or do i need to use the THCAD2 board an then connect the frequency output to the 7i97T? also since it has ohmic sensing and torch breakaway detection wich are 2 wires that trigger two different things, when the torch breakaway circuit opens it senses that the torch disconnected from it's magnetic base and for the ohmic sensing it had another wire on wich when the torch touched the metal plate it closed a circuit and sent the signal to the old thc board that the metal plate was found and the zero was set. can the torch breakaway wire and the ohmic sensig wire be connected directly to the 7i97T board or would i need another THCAD2 Board to have these 2 functions?

Z axis motor:
the old cnc control THC board controlled the Z axis motor wich is powered by 24VDC and since i will be removing that board i won't have a driver for that motor to use, i wanted to replace it with a new servomotor and i've seen the "stepperonline" 100w 230Vac servomotor with his dedicated analog drive,  would that be compatible to be controlled by the Mesa 7i97T? i'll add a picture and the manual to that. 

How to wire the analog servo drives to the 7i97T?
i've read multiple times the manual for the 7i97T board but i'm struggling a little bit to wrap my head around how i should connect the motor drives to the I/O board. i have all the wiring diagrams of the machines wich are very detailed so i've been able to locate all the encoder wires plus the +/- 10v signal and 0V. i still have to understand how to connect the drives to the board correcty.. it seems to have a circuit on the X and Y drive wich is 24VDC generated by the drives for the drive enable signal. i'll add pictures at the end of this topic.

Are all of the current motor drivers on the machine compatible with the 7i97T?
the X and Y axis use the same model of motor driver wich is a TDE-Macno DMBL7 i'll add the manual for that at the end of the topic.
the K axis has a Axor industries mini magnum  MM230T 6/12 drive, i'll add pictures of that too.
this is the new Z axis motor and driver that i'm looking to get. Motor: A6M40-100L2A1-M17 Driver: A6M40-100L2B1-M17 i'll attach the manual and a few pictures of this too. 

Is a Raspberry PI5 suitable for the application?
i wanted to make sure before buying one that the Raspberry PI5 is suitable for my application or if it would be better to get a normal pc.

Thank you in advance for the help.



 

Hi Mark, thanks — that’s an interesting idea.

Technically, running two separate LinuxCNC instances on two physical PCs (one dedicated to motion control, the other acting as PLC/HMI) could meet the functional requirements.

However, for our target environment — multiple non-G-code operators, industrial maintenance, and potential future machine sales — we prefer a clearer separation of roles:
LinuxCNC dedicated strictly to deterministic motion control, and a real industrial PLC + HMI handling sequencing, recipes, interlocks, and operator interface.

On the motion side, we are currently planning to use Mesa Electronics hardware (for example 7i96S with 7i84U remote I/O and THCAD-2), but the exact hardware is not finalized yet. LinuxCNC would remain focused purely on motion and kinematics.

Using two PCs increases overall system complexity (two OS installs, updates, storage, diagnostics, etc.), and it still doesn’t fully meet the typical industrial expectation of having a dedicated PLC for troubleshooting, maintenance, and customer acceptance — compared to using a conventional PLC platform (e.g. Mitsubishi, Omron, Beckhoff, etc.).

Safety will be handled by dedicated safety hardware (E-stop, STO, safety relays or a safety PLC), independent of whether LinuxCNC or PLC is used for logic.

So at the moment we are leaning toward a PLC + HMI + LinuxCNC motion architecture rather than using a second LinuxCNC instance as a PLC replacement.

Cheers!

Thanks for the update — much appreciated.

That timeline works well for my planning. I’ll wait for the 7I84U and 7i96S restocks and proceed with the all-Mesa setup as discussed.

Thanks again for the clarification.

Note our Email is borked for a while

7i84U is probably next week and the 7I96S about 3 weeks out

Thanks — that’s a good point. I did see that the 7i96 (non-S) is currently in stock and that it would work for THCAD-2 and encoder input.

That said, for this machine I’m trying to stay fully within the Mesa ecosystem with maximum flexibility and isolation, and to keep things future-proof in a noisy industrial environment. Even if I don’t strictly need 0–10V today, the added analog output and larger FPGA on the 7i96S make it more attractive for my long-term use.

If 7i96S restock is expected in the near term, I’m inclined to wait and standardize on that rather than mixing generations.

If you do not need the 0-10V analog output for VFD, there are in stock Mesa 7i96 without the S, they do have an encoder input:
store.mesanet.com/index.php?route=produc...oduct&product_id=311

Thanks Peter — one additional note: I also see that 7i96S and 7I84U are currently showing as out of stock on the Mesa store.

My preference is to stay fully within the Mesa ecosystem (rather than using generic BOBs), so if there are any expected restock timelines for 7i96S and 7I84U, or recommended current-production alternatives that keep a similar architecture, that would be very helpful for planning.

I can wait a bit if needed, but I’d like to avoid purchasing from Europe if these boards are expected to be restocked or revised in the near term.

Thanks Peter — that’s very helpful.

That aligns well with my use case. Since the IL-1000 is only ~10 Hz bandwidth and Y motion is intentionally slow, trading loop bandwidth for higher effective resolution via low-pass filtering sounds ideal for stable stand-off control.

Given that, THCAD-2 looks like the right solution for the current phase, especially with it coming back in stock shortly.

For any future higher-speed sensor upgrades, I’ll revisit true ADC options like the 7i87 if needed — but for now THCAD-2 + filtering seems well matched to the application.

In addition, I will need extra isolated digital I/O for valves, interlocks, and machine signals. I was looking at the 7I84U isolated remote field I/O card (sourcing/sinking outputs), but it currently shows as out of stock. My preference is to stay within the Mesa ecosystem rather than using generic BOBs, to keep things robust and well-supported in an electrically noisy environment.

If you have any guidance on availability of the 7I84U, or alternative Mesa smart-serial I/O options that integrate well with 7i96S for isolated field I/O, I’d really appreciate your recommendation.

Thanks again for the detailed clarification.

The THCAD2 should be back in stock in the US by the end of the week.

Our other analog input card (the 7I87 6 channel +- 10V card) will still be about 4 weeks
but you don't need 6 channels...

For the THCAD2, the update rate is the servo thread rate (giving a loop bandwidth
of about 300 Hz at ~10 bit resolution) You can get better resolution by low pass
filtering (in hal) the frequency signal at the expense of loop bandwidth of course.

 If your height sensor only has 10 Hz bandwidth, you could easily increase the resolution
(to 12 bits or so) by this filtering since it will not affect system loop bandwidth significantly.

Thanks for the feedback — appreciated.

To clarify, my primary focus right now is using the Keyence IL-1000 for slow stand-off correction. Based on the discussion, I agree that THCAD-2 into a 7i96S encoder input should be sufficient in terms of raw speed and isolation for this use case.

My main concern is less about servo-thread rate and more about effective sensor update rate, frequency-to-velocity measurement noise, and required filtering/deadband for stable Y correction in a noisy industrial environment.

I’ve contacted Mesa support regarding isolated analog input options to complement a 7i96S-based system, but haven’t received a response yet. At the moment, many Mesa ADC-related boards appear to be out of stock in the US, and I’m considering purchasing from Europe. However, I’m a bit concerned about committing to hardware if Mesa is planning to release newer or replacement analog/ADC solutions in the near future.

If you (or others) have practical recommendations for current Mesa ADC hardware that works well with 7i96S, or insight into Mesa’s roadmap for analog input, I’d really appreciate hearing them.

LK-G3000 is only a possible future upgrade — the current design focus is on making IL-1000 work robustly and predictably.

All that seems easy enough and Mesa combo should be more than enough fast for everything you mentioned.
1. Yes
2. No, unless you need something extremely fast, 1000Hz is normal servo rate, and even that can be pushed further
3. should all be doable easily, and 10Hz is very slow
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In general, plasma is the biggest offender regarding EMI noise, so you should be perfectly fine, granted the wiring and grounding and shielding is done correctly.
Regarding XYZ, it will be much easier to do a normal CNC machine setup, everything else can be set in gcode or some automated VCP panel to make use much easier and requires one time setups.
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I have been tasked with such painting automation about 15 years ago but the financing failed, still had some time to do some thinking about implementation, hence i might be a bit fuzzy on details.
Go for it, that would be my personal advice.

Hi all,I’m building a large vertical machine for laser cleaning and automated spray painting of heavy equipment (excavators, cranes, large fabricated parts and enclosures).Motion concept is a raster-based process:

• Z axis performs the working stroke (up/down) where laser cleaning or spray painting is applied
• Y axis is used only for slow stand-off distance control (surface following)
• X axis is used only between strokes for step-over / overlap indexing, then the next Z stroke starts
  
  For painting, we use automatic air spray guns (not airless / not AAA), since painting is done in a general workshop area without a dedicated spray booth. Typical overlap is around 60–70% between strokes.Current and planned hardware:
  • Mesa 7i96S (Ethernet, step/dir drives)
  • THCAD-2 for isolated analog-to-frequency input
  • Keyence distance sensor (starting with IL-1000, possibly upgrading to LK-G3000 series later)
  • Current: manual air spray gun 
  • Planned: automatic air spray gun 
  • Typical speeds:
    • Z working stroke: ~15–40 mm/s
    • X step-over between strokes: index only (no distance control)
    • Y axis: slow stand-off correction only
      
      Environment is electrically noisy (industrial equipment, welding, laser), so isolation is important.My questions:
      1. For this type of slow stand-off control on Y, is using THCAD-2 into the 7i96S encoder input a reasonable approach (non-plasma use)?
      2. If I upgrade to a faster sensor (LK-G3000), does THCAD-2 become a bottleneck for meaningful improvement?
      3. If I want proper fast isolated analog input, which Mesa hardware would you recommend to add ADC capability to a 7i96S-based system?
      4. Any practical tips for filtering, deadband, and loop rates for a ~10 Hz sensor like the IL-1000 in this application?
         
         Thanks in advance for any advice.

So I built a CNC plasma cutter out of garbage.... and since I built it out of garbage, I used a very old computer to run it.  It's a 32bit computer, so I'm stuck running Linuxcnc 2.8.  I got a base configuration working and running fairly well, but because it's made out of garbage, it really needs torch height control.  I got a THCAD and got everything wired up to my Mesa 7i96s, and ran the PlasmaC configurator.  The buttons on the bottom of the screen work, I can test the ohmic probe, and the probe cycle seems to work, but I can't get any of the GladeVCP components to load.  The tabs are there, but they're blank, and if I try to configure it with a Run panel instead of the run tab, it doesn't show up.  The other issue I have is I can't load a G-code file, it seems to get stuck "Filtering."  On top of that, I'm now having latency issues I wasn't having before.  I've been staring at and trying to troubleshoot my configurations for way too long and I can't find anything obviously wrong, so I suspect this 20+ year old Dell just isn't up to the task.  Part of the "art" of this machine was that it's made of junk, so if I can keep using this computer, I'd like to... but I'd also like the machine to work properly, so I figured I'd at least upload my configs for someone more knowledgeable to look at before I buy something more modern.