Central Scene Primer needed


I've been using HE for just short of a year and VeraPlus before that. I'm embarrassed to say I've never been able to wrap my head around the "Central Scene" concept. It would appear to be somehow related to associations but I can't seem to put together a high level image in my mind.

Any help would be much appreciated :slight_smile:

So, "central scene" support in Z-Wave is really just a way for some device (often a switch or dimmer with multi-taps today, it seems) to send a "scene number" to the hub (that's what makes it "central"), which can then do whatever it wants with that information. (The "scene" part of the terminology probably both refers to its intended use--people using scene-like automations triggered by this--but also to indicate a difference from old Z-Wave "scene controllers" that send simple commands like on/off or dimming directly to devices without involving the hub).

In Hubitat, it's up to the device driver to do whatever it wants with the scene information, but all the drivers I'm familiar with send scene commands from the devices as some sort of button (e.g., the HomeSeer HS-WS200+ sends two taps up as something like "button 2 pressed," two taps down as "button 3 pressed," and I'm pretty sure it also does "button 1 pressed" for a single tap up along with "button 1 held" for a hold of the "up" side, and so on--but please don't quote my numbers on this because I never remember which way is which). You can then use this event in Hubitat as a trigger for any automation. Button Controller is a natural choice for an app to use to set this up, but most lighting apps also allow you to choose a button to trigger something, and of course, there's always Rule Machine or a custom app.

But basically, in Hubitat, they are (usually) button presses (or holds), then you can do whatever you want with that event--something "scene-like" as they were probably intended to be used, or not. :slight_smile:


Thank you for your response.

Perhaps I was over thinking the "Central Scene" capability as some more involved actions.

Currently I have a Inovelli switch for my front entrance light. When I tap the toggle ON, a command is sent to the controller. A rule in R-M reacts to the command sent from the Inovelli and turns on the garage light.
From your description would this be an example of a "Central Scene"?

If so, it seems the "capability" of "Central Scene" is touted to be far more grandiose than it actually is.

This translates to button controller on HE, most central scene devices are capable of push, hold, double tap, some can do release as well.

@mike.maxwell @bertabcd1234

Thank you both, I was thinking it was more than it turns out to be. If I were to make a formal definition it would be:

Z Wave Central Scene Capability

Is the ability of a device to send an unsolicited command to the hub based on physical inputs** to a device.

** i.e. pressing the toggle on a switch twice, or pressing and holding etc.

I don't know how the Inovelli switch works, but if it fires a central scene event/number for a single press up, then I guess so. :slight_smile: (I assume it does since it has the option to disable the internal relay, effectively just making it a hardwired scene/button device. If it's the switch itself turning the non-smart garage light on due to the traditional action of powering the load leg of the switch, same as flipping a "dumb" switch then, of course, it's not really a scene.) Basically, central scenes are events that devices can send to the hub and have the hub react however it wants to. In Hubitat, they are exposed as button events, which seems logical to me since that's what most of these devices themselves are.

It sounds like you might be thinking of something else, though, too: direct association. This could, for example, let you turn on switch 2 when switch 1 is turned on via direct Z-Wave communication between the switches, no hub involvement necessary. This may be a bit faster and saves some Z-Wave traffic, but it's much more limited in what you can do. Inovelli switches do support this (and Hubitat supports setting this up), which you can read a bit more about here: [RELEASE] Inovelli Device Drivers - #19 by ericm

(I honestly don't understand the differences "old" Z-Wave scenes vs. direct association since, coming from ST where the former wasn't really used and the latter was quite rare, I didn't use either. You'll definitely get the most flexibility from involving the hub, plus it lets you control non-Z-Wave devices too, but the few yet possibly important advantages mentioned above do remain.)

I do understand association (directly from device to device).

I've looked at the Inovelli drivers and the model that accommodates "scenes" has event calls, i.e.

"def zwaveEvent(hubitat.zwave.commands.centralscenev1.CentralSceneNotification cmd)"

I feel embarrassed that the such a simple concept was getting the best of me :frowning:

Not embarrassing at all! Some Z-Wave controllers are more explicit with their "Z-Wave scene" implementation. HomeSeer, for example, creates a Z-Wave Central Scene "node" (almost like a device/child device in Hubitat world), along with a node for the switch/dimming capabilities itself or whatever device you're using. I read about this a bit when I bought the HS-WS200+, and saw a thread similar to this one demonstrating how it might be set up on their platform: https://forums.homeseer.com/forum/homeseer-products-services/homeseer-z-wave-products/homeseer-dimmers-switches/95090-homeseer-switches-double-tap-triple-tap?t=181584&highlight=scene (screenshot there that shows you more explicit scene terminology).

Hubitat just chose to make all the stock drivers (and every custom driver I've seen) respond to Z-Wave Central Scene commands by generating "button" events (e.g., pushed and held), as you probably saw in the code you referenced above. This probably owes to convention established on ST, where most "drivers" (DTHs) did the equivalent, certainly not a bad idea given that most scene devices are somewhat button-like anyway. This also avoids needing to add an extra capability to the platform when the existing button capability(ies) can be leveraged for this purpose. You could technically modify the driver code to do whatever you want rather than generating button events; the only role Hubitat's Z-Wave implementation itself has is responding to the central scene event from the device and running whatever, if any, code the driver has for that event. (Some Z-Wave controllers don't support central scene commands, which is why you'll see marketing materials for these devices advise that your controller should support them in order to use all features.)

You're right, though, it sounds less exciting when you think about it. :slight_smile: But it's pretty neat since unlike direct association and "old" Z-Wave scenes, involving the hub lets you include any device your hub supports, including non-Z-Wave devices, in whatever the desired action from activating your "central scene" is. It is, perhaps, less exciting to those of us also used to ZigBee, where button devices--albeit not a lot of good ones--have been around for a while and we've effectively been able to do the same thing without the fancy name, whereas older Z-Wave "button devices" like the Minimote have long struggled to be used easily on hubs like ST and now Hubitat.

My frustration with many of these concepts is that all the Googling I did showed me how to do it with such and such system. Never once (that I found) did anyone simply state an overview of the concept. This is one of the reasons I repeated my understanding as concisely as I could, I'm hoping others will learn from this thread.

Thanks again for you responses.

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