Read it paying more attention:
https://msdn.microsoft.com/en-us/library/aa450503.aspx.
Don't you see something strange? You never read "comm state" of anything physical. In the example, for example, you read defaults. How?
Here is the thing: the port itself does not have any particular state. It will do what you tell it to do. Generally, there is a little sense in reading it with
GetCommState. You will read what is prescribed in some date of the software, either the defaults or the values you put there during your last call to
SetCommState. And your whole question, likewise, makes little to no sense.
The communication parameters are the properties of some device on the other end of your RS-232 cable. Both devices, your computer and the remote one, should use matching parameters, that's all. You just need to know them in advance. If that remote device is another computer or some more or less advanced thing, you could have some protocol of starting with default values at low baud rate, negotiate over the use of optimal parameters (using data communicating through the channel and some common protocol for that) and then change the baud rate, and maybe handshake and something else. This is rarely used. More typically, you simply read from documentation what the other end requires and meet these requirements.
Sounds not very promising? But who told you that serial port communication is supposed to be something good? This is old trash based on the standard of 1997:
http://en.wikipedia.org/wiki/Serial_port,
http://en.wikipedia.org/wiki/RS-232.
—SA
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