Eckler Software offers a unique USB solution for CNC controllers with the rt-stepper USB-to-Parallel dongle. Users can use the rt-stepper dongle to convert a parallel port CNC controller into a USB CNC controller. Designers can integrate the rt-stepper dongle hardware into there own CNC controller.
Most CNC controllers are designed to be driven with a PC parallel port. Unfortunately parallel ports are thing of the past and many new PCs have no parallel port. Commercial USB-to-Parallel dongles do exist, but these dongles are designed for printers not CNC controllers. CNC controllers require XYZA step/direction signals. With the rt-stepper dongle you can now drive XYZA step/direction signals over the USB bus.This works like Hal2arduino but much more polished software. Has it's own GUI called pymini. Prices for dongle range from $60 to $80 depending on if you want case for dongle. Maybe Mark can get this in the openbuild store.
USB interface dongle pymini 2015-09-24
USB interface for Windows, Linux and MAC