this simple circuit worked with PIC serial TTL to USB for send/rcv to PC. Just used a second USB to serial converter and actually used a 1K ohm R, then can view both sending and receiving. Open another instance of hyper-term or other terminal program. You could add 3rd USB/serial device and open another terminal prog and see separate send rcv windows
Name: ht3.PNG Views: 3227 Size: 10.8 KBName: ht1.PNG Views: 3135 Size: 269.5 KBName: ht2.PNG Views: 2848 Size: 171.6 KB