Baud rate mismatch or conflicting COM port. Fix: In Device Manager, right-click the Redsail COM port → Properties → Port Settings. Set Bits per second to 115200 (default for Redsail RS720C). Disable "FIFO buffers."
Legacy driver compatibility issues. Fix: Run the installer in Windows 7 compatibility mode:
LightBurn users do not need to install separate vendor software. Once the Windows USB driver is active, LightBurn will detect the RS720C automatically when you select "Ruida Controller" as your device type.
: Unplug the USB cable from your computer.
Ethernet is often more stable for large engraving files and eliminates USB driver conflicts entirely.