Looks like a home-cooked BTR, Looks like there is only a couple of wires going to the 25pin D socket so I would guess it is a serial to parallel conversion.
If you are lucky and it has its own firmware (EEprom) or dedicated USART chip, then you could try hooking up to a PC serial port and use any Modem program DOS or otherwise, the only problem is you may have to try a few different protocols, baud rates etc to get anything to work.
Cimnet sell a Fanuc reader BTR replacement system that may work, if you are looking for an alternative.
Al.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.