Beam Bench Docs
TroubleshootingConnection

Disconnects mid-job

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

You see

A job is running, then Laser Control flips to Disconnected, or the streaming pauses, or the machine stops responding. You may see partial output on the material, sometimes catastrophic if the laser parked over the work and continued firing momentarily.

What is happening

The serial link between Beam Bench and the controller broke briefly. Causes range from cable issues to electrical interference to driver bugs to OS scheduling issues.

This is also a safety concern because a stuck or confused machine can damage material or, in worst cases, start a fire.

Fix

If the USB cable is the problem

  • Replace with a known-good shielded data cable.
  • Avoid extension cables and USB hubs (use a direct connection).
  • Keep the USB cable away from the laser power supply and motor wiring.

If there is electrical interference

Diode laser power supplies and stepper motors generate noise that can disrupt the serial line.

  • Add ferrite chokes near both ends of the USB cable.
  • Improve grounding of the machine chassis.
  • Make sure the controller and the laser power supply share a common ground.

If the computer is going to sleep

Some operating systems suspend USB devices on power saving.

  • macOS: System Settings → Battery → Options → keep "Prevent automatic sleeping on power adapter" on.
  • Windows: Control Panel → Power Options → choose "High Performance", disable USB selective suspend.
  • Linux: depends on your power manager.

If the driver is unstable

Older driver versions (especially CH340) can crash under sustained traffic. Update to the latest driver.

If something else is hogging the system

CPU spikes can starve the USB host of timely interrupts. Close heavy apps during a job. Some antivirus programs interfere, pause them.

If it always happens at the same point in a job

The job's G-code may include something the controller does not handle. Send a feedback report with the project file.

Recovery

After a disconnect:

  1. The machine may be in alarm state. Use the Move panel → Unlock.
  2. Use Move → Home to re-establish position. Do not assume the head is where the last command put it.
  3. Inspect the material to assess what part of the job completed.
  4. Reconnect and decide whether to re-run from scratch or pick up where it left off (rare and error-prone).

Still stuck?

Port is not listed

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

Baud rate mismatch

Connected but seeing garbled characters or no response at all. The serial speed does not match.

On this page

You seeWhat is happeningFixIf the USB cable is the problemIf there is electrical interferenceIf the computer is going to sleepIf the driver is unstableIf something else is hogging the systemIf it always happens at the same point in a jobRecoveryStill stuck?