Tim, USB->Parallel adapter cables seem not to pass through the device ID of the printer, nor do they have their own device ID. It seems that they answer the request for the device ID with some arbitrary noise or an arbitrary pointer. See bug 468701, comments #30, #36, and #37. This causes the "usb" CUPS backend to skip the device or to segfault.
Tim, USB->Parallel adapter cables seem not to pass through the device ID of the printer, nor do they have their own device ID. It seems that they answer the request for the device ID with some arbitrary noise or an arbitrary pointer. See bug 468701, comments #30, #36, and #37. This causes the "usb" CUPS backend to skip the device or to segfault.