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Connection Issues

Use this page when AxioCNC won’t connect to your CNC controller, or the connection drops.

Cannot connect to machine​

Symptoms: Test Connection fails, or Connect never succeeds.

Checks:

  1. Port — Correct port selected in Settings → Connection? On Windows, check Device Manager → Ports. On Linux/Pi, ls /dev/ttyUSB* /dev/ttyACM*. Use Refresh in settings.
  2. Baud rate — Matches the controller (often 115200 for Grbl)? Wrong baud can cause immediate failure or garbage.
  3. Controller type — Grbl, Marlin, Smoothie, or TinyG must match your firmware.
  4. Power and cable — Controller powered on? USB cable firmly connected? Try another cable or USB port.
  5. Port in use — Close other apps (other CNC software, serial terminals) that might have the port open. Restart AxioCNC if needed.
  6. Linux/Pi: User in dialout group? Run groups $USER. Add with sudo usermod -a -G dialout $USER, then log out and back in.

Connection drops​

Symptoms: Connects, then disconnects after a while or during a job.

Checks:

  • USB — Loose cable, bad port, or power-saving. Try a different port or cable. Disable USB power saving on the host if possible.
  • Baud / buffer — High feed rates and long lines can overrun the serial buffer. Try 115200 if you’re higher, or simplify/slow the G-code.
  • Electrical noise — Route USB away from motors and power. Use a ferrite or hub if available.

Wrong controller type​

Symptoms: G-code errors, weird behavior, or no response.

Fix: Set Settings → Connection → Controller type to match your firmware (Grbl, Marlin, Smoothie, TinyG). Restart the connection.

Baud rate mismatch​

Symptoms: Connect seems to work but you get garbage in the console, or the controller doesn’t respond.

Fix: Set baud in Settings → Connection to exactly what the controller uses (e.g. 115200 for Grbl). Check the controller’s config (e.g. Grbl $ settings) or manual.

Next steps​