I use a Topfield TF4000 PVR but RS232 is connected to PC at one end and Season Interface at the other (not connected to receiver, as already explained I use HARDWARE Dragon or T-Rex CAMs), So connection is from Fausto/PC to Season Interface/Hardware CAM, not receiver. ie Season TAB of Fausto not Serial TAB which (I assume) is the connection method you are trying to get working.
The Fausto PDF explains connection methods (server/client also), I am sure we already have screenshots for various receiver connections also.