Control a generator with a control volage by serial port RS232

Hello everybody,

I would like to control a generator thanks to a control voltage. This last one would be sent to a switch wich turns on the generator.

To do that, I want to link the switch and the computer with a serial port RS232 by using NI-USN 232 cable.

I made some research on this subject and I am only a beginner on LabView but I would like to use one (or several) pin which will send 5V in voltage when I want.

Is that possible? Is there another way to make it?

Thanks in advance.