I need to send and receive data over serial connections (RS-232 and RS-422).
How do I set up and communicate with such a connection? How do I figure out what the configuration settings (e.g. baud rate) should be and how do I set them?
In particular, I am looking to do this in Java, C/C++, or one of the major Unix shells but I also have some interest in serial programming using Windows/Hyperterminal.
For C/C++ on Windows you have (at least) two choices:
The .NET option will be much easier.
From the other side, if you want to do it using C#, which will run on both Windows and Linux--with some limitations (EDIT: which may be out of date. I have no way to test it.). Just create a SerialPort object, set its baudrate, port and any other odd settings, call open on it, and write out your byte[]s. After all the setup, the SerialPort object acts very similar to any networked stream, so it should be easy enough to figure out.
And as ibrandy states, you need to know all these settings, like baud rate, before you even start attempting to communicate to any serial device.