I think the safest assumption is that those pins (which have multiple different functions), when used with the RS-232 interface adapter, would be for connection to computers with genuine RS-232 serial ports, with +/- 5 to 12 V levels, inverted logic.
It makes no sense to dismantle and hack such an expensive scanner, when a simple RS-232 level adapter like that linked in reply #2 is more or less guaranteed to work.