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You probably only want to have one instance of the class for each serial port you are connecting to.

Where is the variable: port defined? Is it scope where you are trying to use it?

A variable defined in a method is only available to code in that method. Define the variable at the class...

You should move most of the code out of the main() method into a non static method in the class.
Have the main() method only call the class's constructor.

If this is not it, post the code with...