This topic provides a brief overview about USB bulk transfers. I have for a long time been wanting to do a Custom USB class driver on the RT106x devices.Each USB transfer is one packet, which can be up to 64 bytes if using bulk type. If you want to send more than 64 bytes, you have to use multiple packets. In this topic, you'll learn about a USB bulk transfer and how to initiate a transfer request from your UWP app that communicates with a USB device. Bulk Transfers are used for data which are not of the type Control, Interrupt, or Isochronous. Try the winusb call WinUsb_WritePipe() for transfering data using bulk transfers. A interface handle is required before we can use WinUsb calls. I am trying to communicate between PC and uC using Labview USB RAW. I have successfully read and write data in interrupt method.