Beam Bench Docs
TroubleshootingConnection

Port is not listed

The serial port for your machine does not appear in Beam Bench's port dropdown.

You see

You click Refresh in the port selector and the list does not include your machine. Maybe other ports show, maybe none.

What is happening

Beam Bench asks the OS for available serial ports. The OS only lists ports it can see, which requires a working driver and a connected device. If the port is missing here, the OS does not see it either.

Fix

If the machine is unpowered or unplugged

Obvious but worth checking. Plug in, power on, click Refresh.

If the cable is charging-only

Some USB cables (especially short ones from charger-sets) only carry power, not data. Swap for a known-good USB data cable.

If the driver is missing (Windows)

For most diode and small CO2 lasers, the USB-serial chip is CH340 or CP210x. The driver does not ship with Windows by default.

  • Open Device Manager.
  • If you see "USB Serial" or "Unknown device" with a warning, you need a driver.
  • Download CH340 driver (search "CH340 driver Windows") or CP210x driver (Silicon Labs CP210x VCP driver) and install.
  • After install, unplug and replug the machine. The port should now appear.

See Windows driver issues.

If permission denied (Linux)

The port may exist but be invisible to your user. Add yourself to the dialout group:

sudo usermod -aG dialout $USER

Log out and back in. The port should now appear.

See Linux serial permissions.

If "Show all ports" might help

The Connection tab of Device Settings has a Show all ports checkbox when some ports are being hidden by filter. Try it.

If macOS asked for permission

Some macOS versions prompt for serial port access. Check System Settings → Privacy & Security for a Beam Bench prompt and approve.

Verify the port exists at the OS level

If Beam Bench does not see it but the OS does, that is a Beam Bench bug, file a report.

  • macOS / Linux: 
    ls /dev/cu.* /dev/tty.* /dev/ttyUSB* /dev/ttyACM*
  • Windows: Device Manager → Ports (COM & LPT).

If the OS does not see it either, the issue is the cable / driver / hardware, not Beam Bench.

Still stuck?

GRBL error codes

What error:N and alarm:N mean, and how to clear them.

Disconnects mid-job

The connection drops while a job is running. The machine may stop, freeze, or behave erratically.

On this page

You seeWhat is happeningFixIf the machine is unpowered or unpluggedIf the cable is charging-onlyIf the driver is missing (Windows)If permission denied (Linux)If "Show all ports" might helpIf macOS asked for permissionVerify the port exists at the OS levelStill stuck?