take the machine OFFLINE, and then it depends on the OS running on the pad. Basically, once you get in, there's an icon that looks like a plate coming off the drum, and you press that. In there it has an image of a plate unloading in front (left), and one unloading in back (right). Choose the one that unloads in back and put back online.
Corn is correct. I am currently running an 8600. When set to Manual Unload, it will eject through the front door. When set to Automatic Unload, it will spit them out the back slot, to the conveyor. This is how I have it set up. It will indicate all of the active paths of travel, on the little 8-bit schematic on the display. It uses lines with arrows and circles to represent rollers. It's rudimentary. I can take a pic of my setup, if you need further clarification.