A module that plugs into an IRF-6 port on one end, and into some device with a serial interface on the other end (e.g. home-theater PC). In the T2 Designer software, you can specify that a button push or a macro step should send a string of characters to the IRF-6 port. The CM-232 will convert that into a standard signal as expected by serial interfaces (what is usually done by a 16550 UART in a PC).