I didn't really follow your description of what you have tried. I suspect the DE9 connector you have is not wired for plugging into a pc serial port but is intended for a DE9 connector on some DEC equipment which is wired differently (a VAX 2000 for example). My suggestion for an MMJ to other serial device connection is as follows: Cut an MMJ to MMJ cable in two. Take one end and strip off a bit of the outer insulation. Strip back the two centre conductors and join them together and to signal ground on the pc side. Strip back the next two outer conductors and connect one to TX on the pc and the other to RX on the pc. Ignore the two outer conductors. Plug in and test. If it doesn't work, swap the conductors going to TX and RX and try again. Regards, Peter Coghlan.