confusion on real ports and connections

I have a Digi PortServer TS 4 - with 2 serial connections going into it. Currently I have the 2 connections plugged into ports 2 and port 3. I look at the digi portserver connections and it shows tty 1, no user, connect from (server IP), connected too (real port 1), and the other is basically the same but its tty 2, and real port 2. The serial connections from the server are set as (plugged into port 2) com=port 5, 9600, N, 8,1, and the other is (plugged into port 3) com=port 4, 9600, N, 8,1. Thats the current config and what I see. Now if I take the port 3 (plugged in) connection and change it to say com=port 7, 9600, N, 8,1 - the digi connections will change too tty 4, and real port 4. It will also change tty and real port depending on what serial configuration I do.