Lefty seems to be in a bad mood today...
I thought you could use input from your device and the FTDI chip on the same line
But is does not work that way. Any one trying to pull the line low would stop at 2.5 Volts.
So please do not use that resistor at all! Sorry - I had my mind on other things when posting in this thread...
(BTW, it had worked with the +/- 12 volts rs232 signals )