Hi,
of course you can, you need LV realtime, as you stated, and of course, you need to know the protocol being used from the all in one sensor to output data (in general, it's a simple one).
About using RS-232 on cFP, it's the same as using PC's RS-232 port with labview. I currently use 2 232 and 1 485 port of my cFP-2020, it's quite easy...
I had some problem with hardware flow control, but in general it isn't used, and maybe it was my fault, and I had to work a little to make it work properly, but often it is not used.
Hope it helps....
graziano