The 6-inch mini-DIN8 to male DB-9 adapter cable (SGI part number 018-0650-001) makes the DB-9 end of the cable the same as that of an Origin 200 server ttyd1/ttyd2 for RS-232 only, not for RS-422.
The RS-422 Mini-DIN8 to DB-9 adapter cannot be used with Video Server Toolkit.
Table B-1 summarizes the SGI RS-422 pinouts at the DB-9 end of the Macintosh mini-DIN8 to female DB-9 adapter cable.