The Firecracker interface is a small module that connects to your PC serial port and send out RF signals to your transceiver module. The Activehome kits interface connect from the PC serial port to the PC module which is plugged into an electrical outlet and send X-10 signals through that line to any X-10 module, the PC module has memory for timed events that you download from activehome software to it then if you like you can disconnet the cable between the serial port and the PC module but if you want to operate X-10 module with your PC using Activehome kit the PC must be connected to the PC module through the serial port. I never use timed events so I myself prefer using the Firecracker software allowing me to use my serial for other connections like my pronto connections since firecrackers interface has a through port connection.