Till has perhaps the most comprehensive documentation for connecting a Commodore disk drive to a modern PC – source & schematics are all there….
The xu1541 is the modern way to connect cbm iec bus devices to todays USB equipped PCs and it is meant to replace the printer port solutions based on the so-called original x1541 cable. The xu1541 interface allows you e.g. to attach a VC1541 disk drive to your desktop PC as depicted below. This allows for easy transfer of disk images from and to the old units and helps you preserve your ancient data.
The xu1541 is a proprietary interface. It does not transform the vc1541 into a standard usb mass storage compliant device. Instead it provides a means to send low level iec commands forth and back via the usb. PC software developed to support this interface may then directly access the disk drive and the contents of a disk inserted. It should also be possible to access other iec devices like printers. Currently e.g. the CVS version of the opencbm software supports this interface.
xu1541 – Link.