Change COMx Log "0" & Log "1" via VBasic

I need example (simple) how I can change case on Communication Port (COM).
Log "0" = 0V
Log "1" = 12V
I need this for some work with electronica...

Thanks...

I know how to change:
logic 1:5v
logic 0:0v
if u r interrested
mailto:[email protected]
then i will send u the example
OK?
MIMO