SpiderBot

I use Rostock 2 with RAMBo Controller but Cura is my Slicer of choice. I also use Slic3r and Matter Control to print directly to USB. With Cura, I must save the G-code to SD card and print from the card. Cura looks for the USB port, but never finds it. Can someone tell me how to set what to have Cura find the RAMBo USB port? Thanks