Hi Steindorff,
Yes, that's what you do using Standard DB9 connection which is located in back of your computer. Those DB9 pins on your computer is already predefined as a standard. So, when someone writes a component or control, they use those pins as defined. In other word, it is universal when you say just set obj.RTS := true. The component already knows which pin to toggle on your DB9 connection. You can't change that (Correct me if I am wrong). As far as Raspberry PI goes, you can tell PI to assign any usable PINS on the board as RTS line. So, this information has be applied to the component or in this case Synaser that you are using. Otherwise, it won't work. That's what I am stuck on. I will have to do some more research.
Thanks JP for your help and steindorff thank you for your input.