CompuServe Thread

Could someone please suggest a reference to me for serial communications on the Amiga? I have an A3000 with a 2232 multi-serial card. I am interested in sending and receiving messages through the serial port(s) under ARexx control. I have had limited sucess so far in sending info but not in receiving it. The problem is I don't know the basic methodology that the Amiga OS uses to handle serial communications. So I am basically floundering around in the dark. Once in awhile I get something right but I don't know why. Aside from needing to know the basic structure of the serial handling in the Amiga, what I really need to find out is how to capture responses from serial devices. I have a plotter that can be queried for various info (pen location etc.). I have sucessufully issued commands from an Arexx script to draw lines etc. but when I give it a command that requests information I don't know how to capture the return answer data. Any Help, suggestions, or comments would be appreciated. Patrick