How do I get rid of buffer overflow errors on my CNC machine?

For CNC buffer overflow errors, the process of disabling your ‘FIFO-buffer’ when using the PC’s standard COM ports depends on the version of Windows you are using.

In Windows NT 4:

  • Go to the Control Panel. If ‘Ports’ is available, double-click on it.
  • Choose the port in question
  • Press ‘Settings,’
  • Press ‘Advanced,’
  • Uncheck ‘Fifo enable.’

In Windows 95-98 (all versions):

  • Go to the Control Panel and open ‘System’
  • Find the port under ‘Serial ports’
  • Press ‘Properties’
  • Press ‘Advanced’
  • Uncheck ‘Fifo enable’
  • Reboot your PC after these changes

In Windows 7, 8, and 8.1:

  • Go to the Control Panel
  • Open the Device Manager
  • Press the ‘+’ button next to ‘Ports (COM & LPT)’
  • Right-click on the COM port you wish to change
  • Choose ‘Properties’
  • Click on the tab at the top that says ‘Port Settings’
  • Press the ‘Advanced Settings’ button
  • This will prompt you with a window with FIFO settings
  • Uncheck the box at the top and FIFO will be disabled on your device
  • Reboot your PC after these changes

If this does not help, your cable might be too long, or it may be placed next to a power cable, creating a lot of noise.

For the MOXA NPort series, such as 2150A and 5110, you will need to alter the FIFO setting using the proprietary software used to handle the drivers for your product. If you have a Moxa device then you will need to first run NPort Windows driver manager.

Once it starts, select the desired port, click ‘Setting,’ choose the ‘Advanced Settings’ tab, then set ‘FIFO’ to disabled.

For more information, contact us via Email or call us directly, toll free: 877-611-5825.