@OldSurferDude

Thanks for your comprehensive response OldSurferDude. Judging from the lack of mentions, it looks like the Sensebender gateway never really took off. I will follow your suggestion with RF-Nano, but will need to make sure that the HA Green will support a serial interface (nothing taken for granted now) - will probably go down the RP path if not. Will let you know how I go - I may be away for some time :)