This usually means the FTDI driver is missing or the COM port in your software doesn't match the one in Windows Device Manager. Garbage Characters/Random Cuts:
Download and install the or FTDI driver before connecting the cutter. Seiki 870t Driver UPD Download
If the COM number is very high (above 10), you may need to go to Properties > Advanced to change it to a lower number (like COM1 or COM2) for better software compatibility. : This usually means the FTDI driver is missing