Input A: The unit is triggered when a low voltage is applied to the Input terminals
Input B: The unit is triggered when the Input terminals are connected together. Like with a switch or push button.
Eather way after triggering; depending on the mode switch. The Powerflash will send X10 powerline signals on the House/Unit Code it is set to. I have one set to send an ON when activated and Off when not activated. It is triggered by a doorbell and rings a Chime Module in a remote part of my home. Where I can't hear the doorbell.
If you are triggering a Powerhorn it should be set to send the on off cycles as long as the trigger is on As the Powerhorn needs a on off cycle to trigger. A single on signal will not start a Powerhone to sound.
