Using the serial port is a common task and there are a huge number of components for doing that.
I'm using TCiaComPort by Wilfried Mestdagh for years. It is a freeware with source code available at: http://www.mestdagh.biz/soft_components.html
Recently, I have updated the source code for Unicode enabled Delphi versions. I use it with Delphi XE3 but it should be OK starting from D2009.
My use
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