CutArc Laser connects to your laser cutter directly through the browser — no desktop software required. It supports Ruida DSP controllers (CO2 lasers) and GRBL boards (K40 upgrades, Ortur, xTool, Atomstack, Cohesion3D, and other diode/CO2 lasers). When you click Connect Laser, you'll see connection options based on your selected controller. This guide explains the difference, which one to use, and how to set up drivers if needed.
Serial vs USB Direct: Which Should You Choose?
| Serial | USB Direct | |
|---|---|---|
| Technology | Web Serial API | WebUSB API |
| Driver needed | Uses existing OS drivers | WinUSB on Windows (via Zadig) |
| Works alongside LightBurn | Yes (same driver) | No (replaces FTDI driver) |
| Latency | Normal | Lower |
| Windows | Works out of the box | Requires Zadig setup |
| macOS | Works out of the box | Works out of the box |
| Linux | Works out of the box | Works out of the box |
| Browser | Chrome, Edge | Chrome, Edge |
Start with Serial mode. It works on all platforms with no extra setup and is compatible with existing drivers. Only switch to USB Direct if you want lower latency and are comfortable changing drivers.
Connecting with Serial Mode
Serial mode uses the Web Serial API, which talks to your laser through the operating system's built-in serial drivers. This is the simplest way to get started.
- Plug your CO2 laser into your computer with a USB cable. Most Ruida-based machines use a USB-B port on the back of the controller.
- Open CutArc Laser in Chrome or Edge (other browsers don't support Web Serial).
- Click Connect Laser in the top toolbar.
- Select Serial from the picker.
- A browser dialog will appear showing available serial ports. Select the one that corresponds to your laser (it will typically show as "USB Serial Device" or "FTDI" or "CH341").
- Once connected, the status indicator turns green and you'll see your machine's position and status in the sidebar.
On Windows, the FTDI driver is usually installed automatically when you first plug in the laser. If your machine uses a CH341 USB chip instead of FTDI, you may need to install the CH341 driver manually — search for "CH341 driver" and download it from the manufacturer's site.
Connecting with USB Direct Mode (WebUSB)
USB Direct mode uses WebUSB for lower-latency communication. It bypasses the OS serial driver and talks directly to the FTDI or CH341 chip on your laser's controller.
macOS and Linux
On macOS and Linux, USB Direct mode works out of the box. Just select USB Direct in the picker, choose your device, and you're connected.
If the device doesn't appear in the WebUSB picker, the built-in FTDI kernel driver may be claiming it. Open Terminal and run:
sudo kextunload -b com.apple.driver.AppleUSBFTDI
Then try connecting again. This only needs to be done once per reboot.
Windows — Zadig Driver Setup
On Windows, the default FTDI driver doesn't allow WebUSB access. You need to replace it with the generic WinUSB driver using a free tool called Zadig.
- Make sure your laser is plugged in and powered on.
- Download Zadig from zadig.akeo.ie. No install needed — it's a standalone .exe.
- Run Zadig. From the menu bar, click Options → List All Devices.
- In the dropdown, find your laser. It will typically appear as "USB Serial Converter" or "FT232R USB UART". The USB ID should show
0403 6001(FTDI) or1A86 5512(CH341). - Set the right side (target driver) to WinUSB.
- Click Replace Driver. Wait for the confirmation dialog — this takes a few seconds.
- Close Zadig. Open CutArc Laser, click Connect Laser, and select USB Direct.
Replacing the driver with WinUSB means other serial software (like LightBurn or RDWorks) won't be able to see the device until you switch the driver back. If you need to switch back, open Zadig again and replace WinUSB with the original FTDI driver. For this reason, Serial mode is recommended if you use multiple laser programs.
Supported Hardware
Ruida Controllers
Ruida DSP controllers are the most common controller family in Chinese CO2 laser cutters. Supported models:
- RDC6445G — the most common, found in 60W–150W machines
- RDC6442G/S — mid-range machines
- Other Ruida RDC controllers with USB connectivity
Both FTDI (USB ID: 0403:6001) and CH341 (USB ID: 1A86:5512) USB-to-serial chips are supported.
GRBL Controllers BETA
CutArc Laser also supports GRBL 1.1+ boards via Serial mode. This covers a wide range of machines:
- K40 upgrades — K40 lasers with GRBL replacement boards (Mini Gerbil, Cohesion3D LaserBoard, etc.)
- Ortur Laser Master — diode laser engravers
- xTool D1 — diode laser cutters
- Atomstack — diode laser engravers
- Cohesion3D / MKS SBASE — GRBL-LPC boards for K40 and similar
- Any GRBL 1.1+ board with serial USB connection
GRBL support is currently in beta. To use it, select your GRBL machine profile in the machine setup dialog before connecting. GRBL boards connect via Serial mode only (no USB Direct).
Troubleshooting
No device appears in the browser picker
- Make sure you're using Chrome or Edge. Firefox and Safari don't support Web Serial or WebUSB.
- Check that the USB cable is firmly connected. Try a different cable — some USB cables are charge-only and don't carry data.
- On Windows, open Device Manager and look under "Ports (COM & LPT)" for a USB Serial Device. If it's not there, the driver isn't installed.
- Try a different USB port on your computer. Avoid USB hubs for the initial setup.
"Access denied" error
- Another program (LightBurn, RDWorks, a terminal emulator) may have the serial port open. Close it and try again.
- On Windows using USB Direct mode: you need the WinUSB driver installed via Zadig (see above).
- On Linux: your user may need permission to access USB devices. Add your user to the
dialoutgroup:sudo usermod -aG dialout $USER, then log out and back in.
Device connects but doesn't respond
- Make sure the laser is powered on (not just the computer connection — the laser's main power switch).
- Try the other connection mode (Serial instead of USB Direct, or vice versa).
- Check the CutArc Laser log panel at the bottom of the sidebar for specific error messages.
Want to switch back from WinUSB to FTDI driver?
- Open Device Manager on Windows.
- Find the device under "Universal Serial Bus devices" (it will show as a WinUSB device).
- Right-click → Update driver → Browse my computer → Let me pick from a list.
- Select the original USB Serial Converter driver and click Next.
- Alternatively, re-run Zadig and replace WinUSB back with the FTDI driver.
Ready to connect?
Open CutArc Laser and start controlling your CO2 laser from the browser.
Launch CutArc Laser