i use this configuration for the cable:
PC (9 pin) OP17 (15 pin, IF2 port)
2 -> 4
3 -> 3
5 (GND) -> 5,10,12
it works. before using prosave, turn off OP17, pres ESC and Up key, turn on OP17. wait a second, release the button. the screen will show ready to transfer. run prosave.