The OMTech CO2 laser sits in LightBurn as "disconnected" or fails to home, so you cannot send a job even though the machine powers on and the control panel responds.
LightBurn cannot see the OMTech because of a link, a device profile, or a port mismatch — all software-side. The table ranks what we resolve remotely most often.
| Cause | Likelihood | First Check |
|---|---|---|
| Wrong device profile (Ruida vs the actual controller) | High | Open LightBurn device settings and confirm the controller type and DSP match the OMTech board |
| COM port or IP wrong after a PC or cable change | High | Check which COM port the USB-serial bridge took, or the static IP on the Ethernet link |
| USB-serial driver not installed or wrong port | Medium | In Device Manager, confirm the bridge shows a port and no warning; reinstall the CH340/FTDI driver if needed |
| Communication mode set to UDP when the link is serial (or vice versa) | Medium | Match LightBurn's connection type to the cable you actually use |
| Ethernet IP outside the controller's subnet | Low–Medium | Confirm the PC IP shares the controller's subnet and the gateway is right |
Work through these in order. Every step is in LightBurn or Windows settings — no cover needs to come off.
Open Devices and check the controller type matches the OMTech board (typically Ruida). A mismatched profile is the most common silent disconnect.
Decide USB-serial or Ethernet first. LightBurn's connection mode must match the cable, or it will never find the controller regardless of the port.
For USB, read the port the bridge took in Device Manager. For Ethernet, read the controller's static IP and confirm the PC sits on the same subnet.
If the bridge shows a warning or no port, reinstall the CH340 or FTDI driver. A missing driver is why Windows never exposes a COM port to LightBurn.
Share the LightBurn Devices window and, for USB, the Device Manager port. We confirm the profile, port, and mode so the link comes up.
A CO2 laser that will not connect to LightBurn is almost always a software and configuration gap, not a dead controller. The fixed tells are the device profile, the connection mode, and the port or IP — three settings that all live in the PC. Because nothing mechanical is involved, this is one of the cleanest cases to resolve end-to-end from a screenshot.
For the wider view, see No connection / offline device and Laser controller & DSP communication. On the same machine, OMTech CO2 — Laser Not Firing is the next fault once the link is back. A different control with a similar link-loss pattern is Haas VF-2 — Not Communicating, and the axis-limit angle is Haas VF-2 — Overtravel Alarm.
Send the device settings and we confirm the profile and port. This is software-side, so we address it without touching the laser hardware.
Send the LightBurn Devices window and your COM port or IP. We confirm the profile, port, and mode remotely so the link comes up without a service call.
Submit Your Case Connect With SpecialistsWe do not perform hardware repair, we do not replace parts, and we cannot promise a 100% resolution. Our role is limited to remote diagnostic and step-by-step guidance based on the information, photos and logs you share.
Usually the device profile is wrong, the connection mode does not match the cable, or the COM port or IP is off after a PC change. We confirm all three from your settings screenshot.
Match it to the cable you use. USB needs the right COM port and driver; Ethernet needs the controller's IP on the same subnet as the PC. Picking the wrong mode is why the link never appears.
The USB-serial bridge driver (CH340 or FTDI) is missing or blocked. Reinstall it and Windows will expose a port that LightBurn can then use.
Almost never for a connect failure. The fault is profile, port, or mode in nearly every case. We only suspect the board after those are confirmed correct and the link still will not come up, and we verify that with you.
The next fault once the link is back up.
A different control with a similar link-loss pattern.
The axis-limit angle on a CNC control.