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:
In Windows 95-98 (all versions):
In Windows 7, 8, and 8.1:
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 Wired and Wireless Connect units from SFA, you will need to alter the FIFO setting using the proprietary software used to handle the drivers for your product. If you have one of these devices, 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.