For radio amateurs
the three-antenna changeover PC's using a single antenna cable.
The antenna cable HF signala and DC control
The program can select the antenna 1, 2 or 3 locally ,using an intranet or via the Internet.
Remote application program is the same as the local program.
Control takes place via the serial port (RTS and DTR)


http://remotesmart.wikidot.com/kaukoantenni
You need the relay hardware to operate the software in the picture to do actual control