I want to create an action that will take place if there is a change to the online status of a particular device. Simply, if the device comes online then do x. If it isn't online of course it would do nothing.
I have a Z-Wave device that is normally switched off, but when it switches on I want an action to happen. Other than that, it can remain dormant. I understand the finer points of what this might do to a Z-Wave Network, but it is close enough that it will not and has never caused issues.
The biggest problem you'll run into is that most devices/drivers don't have a way to report on this status (a device that gets powered off can't send a message to the hub saying that, and Z-Wave commands are sent to/from devices as needed rather than relying on a constantly-open "stream" or similar, so the hub doesn't really know, either). The best option might be guessing that the device is offline based on failure to hear something from the device in so long, but that won't really help you with the other half: most devices don't do anything special when they get turned back on, either.
I'm not sure what your particular use for this kind of thing is, so sharing more details about that may get you better ideas of what might actually work — for example, a Ring Range Extender with a built-in battery that can report mains-power status, or a DIY solution involving an AC adapter, relay, and the dry inputs on a contact sensor like this: DIY Smart Power Outage Monitoring Kit - The Smartest House (sold out, but you should still be able to find the parts or use other compatible devices to make it work). Either could help if you're looking to monitor a circuit or outlet something is plugged into being turned on/off for example, and far more reliably than any of the above given how Z-Wave works.
I have that kit installed and monitoring a freezer in my garage, I never really considered this to be the same kind of problem but it is. I appreciate the new eyes looking at the problem.
I most of the kid on hand, except for the 12 volt adapter. So, I ordered one of those we'll see what happens tomorrow when it gets here.
Thanks for the response.
FYI it's actually ties into the other problem I'm having with my ZEN20s. When it was working properly, at Power on, it would immediately flash that zero power had been used which gave me the change signal I needed to trigger a timer for a light. Without that trigger, the light wouldn't turn on and it's timer wouldn't kick in.
My assumption, which seems backed up by the explanation and responses above, is that this isn't just a matter of the switch turning on or off (whether phyiscally or via Z-Wave, ultimately reported via Z-Wave either way) but rather the device getting power physically cut to the "smart" device itself-- i.e., unplugged, circuit turned off, etc.
