Keep the USB cable unplugged until instructed.
Microsoft has strengthened security. The CH340 driver will install but may show "Code 52" (unsigned driver). You must: jk 721 cutting plotter driver
Once you have the jk 721 cutting plotter driver working, keep it stable: Keep the USB cable unplugged until instructed
If you are using Windows 11 64-bit, the CH340 driver works fine. However, some older JK 721 units (pre-2015) require a specialized 64-bit driver from USB-Serial.cn. If your plotter connects but immediately disconnects, you need the "CH340 64-bit signed driver v3.5." If you are using Windows 11 64-bit, the