(The core Mach3 plugin file, sometimes labeled specifically for USBMach).
The BL-USBMACH-V2.1 replaces older parallel port (LPT) setups, allowing modern laptops and tablets to control CNC machinery. 5-Axis USB CNC Motion Controller for Mach3 (BL-USBMach V2) bl-usbmach-v2.1 driver download