to use the USB dongle with a dumb string controller, you need to have the pixelnet firmware. (dumb string controllers are pixelnet only)
(the dumb sting controllers also need a hub to inject the 12v power needed to operate)
to get DMX also, you'll need either another dongle, or an active hub to give you some dmx channels.
the Lynx USB dongle can be used for DMX or pixelnet depending on which firmware is installed.
you can't get both from the device, without flashing for pixelnet, and using a hub to retrieve DMX.
sorry to be redundant, just trying to make it as clear as possible.