Check the plotter’s physical control panel to verify its Baud Rate. Ensure your software matches it exactly (9600 is highly recommended). If the issue persists, switch your software's flow control setting to Hardware .
| Software | Free option? | Notes | |----------|--------------|-------| | | Trial | Works with JK 721 via “Generic HPGL” | | VinylMaster Cut | Free (Lite) | Best free for JK 721 | | SignMaster | Trial | Chinese software – stable | | Inkscape + InkCut | Open source | Requires plugin, COM port config | Jk 721 Cutting Plotter Driver Windows 10
: Look for driver names like CH341SER or FTDI . Many JK 721 models use these specific USB-to-serial chips to establish a connection. Check the plotter’s physical control panel to verify