Please correct me if I'm wrong...

PUM01, I believe, is the same as UM506 Universal Module as listed on the X10.com website. This is a "receiver" device.

The Powerflash interface (PF284) looks similar to the Universal Module, but it's a "transmitter" device.

With the PUM01/UM506, you can, for example, use it to close your garage door at 11 p.m. each night if it isn't already closed. This can be done via the use of a magnetic contacts and wiring it to your garage door open/close button. If the door is closed (magnetic contacts apart), the circuit will be broken, and the activation of the module will not open your garage door. If the door is open (magnetic contacts together), the circuit is completed, and the module can close your garage door.

With the Powerflash interface (PF284), you can set the magnetic switches to be in contact when the garage door is closed. When the garage door is opened, the circuit will be broken, and the interface will transmit an ON command to a nightlight plugged into a lamp module to turn it on. This way, you know that the garage door is open by looking at a nightlight in the house.

What I was looking for is something more like the second example -- a notifier. The garage door kit sold by SmartHome.com is just about the same price as the Powerflash interface.

But yes, the first example is cheaper by almost half.

Roland S