Can not connect to THC

Finally assembled my pro together and then ran into a problem with the thc. I can not get it to connect with fire control. I have a vipercut 30i plasma cutter. I have checked my wiring, updated firmware, manually installed driver and reinstalled firecontrol. Under device manager it is recognized but when loading firecontrol it says “Your USB device signature is recognized by FireControl but cannot connect.” I also tried different usb cables and changed ports on my laptop. Please help… @langmuirsystems

You really should include @langmuirsystems in this request…

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This is an old thread, but was wondering if you recall what the fix action for this was? I’m having the same issue, only I have a PrimeWeld Cut 60. It has the same error, regardless of the Com Port showing up in FireControl and being green.

Tom if I understand this issue it has nothing to do with your plasma cutter. This is the THC module talking to the main board in the crossfire’s control box. Are both devices showing connected in the upper right of firecontrol? There should be 2 green boxes indicating the connection.

Hi Scott,

Here’s a picture of what I see:

As you can see, the radio button to toggle the THC Control to be enabled is grayed out, and there’s that connection help in the top right corner. When I click on that, it shows me the error that the orignal OP mentioned (I tried ti embed it, but being a new user I’m only allowed one picture). I’ll see if I can reply again and post it.

I can enable and manually fire the torch, so that part works, and I can jog through the break in program. Everything but the Z-Axis appears to be working.

Thanks for any guidance!

Here’s what I see when I click on “Connection Help”:

Thanks again!

It looks to me like as the error dialogue says your firmware is not working correctly. Did you reflash the software on the THC as it suggests? The greenbox should include the firmware version just like the machine green button.

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The other thing I might do even before the reflash is to reseat the THC module on the main board.

Yes, re-flashed it a couple of times.

I spose I can try to pull it out and re-seat it. I just saw the red light on the module when plugging in just the USB to my computer and figured I was good to go.

well it’s definitely not working so I would reseat it and then call @langmuir-reilly as you may have a bad THC module. It is definitely not interacting with the main board as it should.

the board gets its power from the usb cable so no need to power up the actual control box.

have you tried rebooting the computer?

when you install the drivers, you need to not have the control box plugged in. disconnect from the table and install the drivers to the computer first, then reboot, then connect to table.


I just had my wife reseat the module since I’m still at work, but I’ll be able to test it again in a bit. As far as reboots go, yes I’ve rebooted a couple of times as well as closed / reopened the application. I also manually downloaded the driver from the downloads page at Langmuir which puts an older 2014 driver on there, reverting from the 2019 driver that Windows natively installed. I’ll re-try the whole setup though - won’t take long.

I would try one thing at a time.

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Re-seating didn’t work, so then I proceeded to re-flash the firmware, which I can’t tell if it did anything to the actual module, and then I manually uninstalled the drivers using the installer with the USB port unplugged, and then re-installed them. I then plugged the USB cable back in, opened FireControl, and it had the same issue. Not sure if there’s some sort of additional application logging in Event Viewer or some sort of file based log with more data in it? I spose I can try to find another laptop and test on another machine.

P.S. - Good to know regarding what you said earlier, where in the green it should show the firmware version. Definitely not showing that, which makes me think that the re-flash attempts also probably had no effect.

I would say the THC module is no good. I would open a ticket with @langmuir-reilly and get their take, they’ll probably send you a new module and my guess is your problem will be solved. Unless they have a way to force the reflash that we don’t know about. It seems like the hardware part is communicating but no software is running on it. It’s interesting that it doesn’t error out during the reflash.

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Today was my first day posting on the forum. I emailed support@langmuirsystems, but didn’t know I could open a ticket on the forum - how can I do that for next time?

You can’t you did the right thing. You can include Langmuir people or anyone else by using the “@” symbol and their user name. When you type the “@” and then start with lang you’ll see some choices. Play around with it.


Did you go thru the THC troubleshooting flow chart? I’ll attach it here.

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Also per the picture in the THC guide, there appears to be a Tx, Rx, and some other lights:

I’ve only ever seen the red power light, 3 down from the top. I’ve never seen the transmit or receive, or the L light at the bottom blink - granted I don’t know what’s supposed to light up and what isn’t.

Update, I just went out and looked and I do see the L light at the bottom flash during the initial communications when plugging the USB cable in and data loads into FireControl, as well as if I click the refresh button for “Height Control.”