Z-Wave Groups and Scenes


(Paul) #1

I need some help in understanding how Z-Wave Groups and Scenes work from a Z-Wave protocol perspecitive (not how some controllers “extend” the functionality. So let me try to put my understanding in the form a number of statements (which may be completely wrong).

(a) only controllers maintain a list of devices belonging to a Group or a Scene
(b) group/scene data can be replicated to other controllers when the controllers support this functionality and a replication is explicipty executed
© a device has no knowledge of it being part of a group
(d) there are no command classes to manage groups, instead the controller sends a BASIC command class to the devices which are part of the group
(e) a device which is included in a scene saves its current state together with the scene ID, e.g. device specific scene settings are stored in the device, not in the controller
(f) when executing a scene, the controller sends a special scene command which includes the scene ID to the device

Any conformation or more detailed information of what happens behind the scene is appreciated.


#2

A) and B) are part of the standard.

The others either have multiple ways of being accomplished, are not true, or are done differently than you describe.

Talking about zwave online is tricky because it’s not an open standard and you’re supposed to buy a developer license to get access to all the docs.

You can discuss solving a specific use case in terms of a particular device, but broader discussions of the type you’re asking aren’t allowed in open forums (which is why you probably haven’t been able to find them online.)

And now that SmartThings is a member of the Zwave Alliance they do have a Contractual obligation to follow those discussion rules.

Why don’t you check out the open zwave project? It’s for software developers, not device builders, and although they walk a fine line most of their shared knowledge comes from observable behaviour shared by people not under nondisclosures. They can probably answer a lot of what you’re curious about, particularly with regard to interfacing with controllers, which of course is what smartapps do.

http://www.openzwave.com


(Paul) #3

Oops 2 out of 6. I guess I flunked the test. :smile:

I guess that the GE/Jasco 45631 is great example of a group and scene controller. http://jascoproducts.com/sites/default/files/product/manuals/45631-Manual-Eng.pdf

I guess it is also it is a great example of why the z-wave conformance statements can be so confusing. http://products.z-wavealliance.org/products/165. It only controller replication as the supported command class and basic as the controlled command class. It doesn’t even lists scene related command classes.

Thanks JD for all your contributions to the forum.


#4

That’s a portable remote controller. As the conformance statement says.

It helps to know that “scene,” particularly with regard to lighting, is a marketing term used by many different manufacturers in many different ways.

It’s technically only a zwave scene controller if it uses the zwave scene command classes.

The Leviton VRSC4 is a true zwave scene controller.

One of the important things to note about zwave is that it’s backwards compatible. So as new command classes get added, the terminology sometimes changes, but older devices don’t necessarily change their own descriptions.

Always start from the conformance statements and licenses. Everything else is marketing.


(Paul) #5

I am still confused when reading the manual of the 45631:

Create or Adding a device to a Scene
Since this is a secondary controller, it cannot add a new device to the network, but it can add a network device to a Scene. The network information must be copied to this device before trying to create or modify a Scene.

  1. Press and hold the Add and Remove buttons at the same time until the Orange LED blinks twice, then release.
  2. Press and release the Add button.
  3. Press and release the Scene button.
  4. Press and release the right side (ON) of the Group/Scene button (1, 2, 3 or 4) that you want to assign the device to. The Orange LED will start blinking.
  5. Press and release the button on the device you wish to add.
  6. The Orange LED will stop blinking and the Red LED will turn ON. The controller is waiting for you to perform the next step.
  7. Adjust the brightness level on the device.
  8. Press and release the Add button. The Red LED will turn OFF.
  9. The Green LED will blink twice to show that you have successfully Added a device to a Scene.

It reads as a scene controller, but the conformity statement states it is a portable remote controller and it only supports the BASIC command class. Is my assumption correct that when adding a device to a “scene” it gets the NIF, stores the node ID in its own list, does a BASIC GET to get the value of the device and when executing the scene, does a BASIC SET to set the value it previously got?

By the way, are Z-Wave Association Groups and Z-Wave Groups the same thing?


#6

JASCO is using their own language there. They took “scene” from what was commonly used to describe lighting set ups with dim levels, not the zwave term, which didn’t have a specific definition when Jasco wrote their manual. Then they made Up their own use of “group” as an on/off group (no dim). Both are just marketing terms, nothing to do with zwave command classes.

As far as zwave command classes, “group” is short for “association group.” But individual manufacturers use the word " group" all kinds of different ways in their own materials. The zwave alliance doesn’t care about that side of things.

What you describe is probably how that GE device works, I’m not sure. It might do something proprietary.

As far as the zwave standard goes, yes, basic command classes.

The Jasco device was ahead of its time when it came out, instituting the general scene concept much the same way some smartapps do it for ST.

But it has since been superseded by the adoption of formal scene and association commands within the zwave standard.

So this is part of the confusion. You keep expecting “group” and “scene” to mean the same thing when used by different manufacturers, but it only means the same thing if used in command classes. Otherwise, there’s no telling.

The concept of lighting " scenes" had existed in home automation for decades before zwave was invented, but they were not included in the original specification. So it was left up to each device manufacturer to determine how and if they would implement scene and group management.

Over time, formal command sets were implemented for scene management, but because of the commitment to backwards compatibility, the only formal zwave definition is the one tied to the command classes. And manufacturers were not required to change their own terminology to retain certification.