Recently i was working with some kind of 3rd party device which support communication only throught Serial Port. So i was so much confused and i was not able to differentiate between Serial Pins. Then i read complete RS 232,422 and 485 Guide. Then i came to know about serial communications and pinouts which could be helpful.
RS-232 (2 Wire communications) (Distance upto 15 meters) (4 Device Supported)
RS-422 (4 Wire Communications) (Distance upto 1200 Meters) (4 Device Supported)
Rs-485 (2 Wire Communications) (Distance upto 1200 Meters) (32 Device Supported)
Detailed Description is provided in the image below:-
Above Given Configurations are provided from my studies from different materials.
RS-485 Connection Wiring Diagram:-
RS-422 Serial Communication Wiring Diagram:-
RS-485, RS-422 Pinouts:-
This is basic information required for Serial communication.
And if you wanna Test serial communication you will need a Software/Tool called ModScan32, Make sure you have connected required 110 ohm resistance at proper connection shown above and then try to connect.Check for error messages and change connection to right position.
I hope that helps