Can a Z-Wave Switch Be Divided Into a Remote and a Relay?

Devices & Integrations
, ,
#1

I have an AEON Labs Z-Wave Micro Switch attached to a LIFX light and I want to try and achieve this setup:

  • I want the micro switch to always be providing power to the LIFX bulb no matter what position the physical switch is in.
  • When someone changes the state of the physical switch, I want it to tell SmartThings to toggle the state of the LIFX bulb, and not actually cut power to the bulb.

You would think this would be possible because the physical switch isn’t in parallel to the bulb, otherwise it wouldn’t be able to maintain power to itself and hence wouldn’t be “smart”.

  • When you toggle the physical switch, you’re sending a signal to toggle a relay.
  • When you toggle the switch in the SmartThings app, you’re toggling the relay but not the physical switch.

Could this work by assigning two different device types (a remote or switch and a relay) to the same Z-Wave ID?

I’m new to SmartThings and find it hard to believe no one has asked this question before. But, I’ve scoured through a bunch of threads on switches and smart lights and haven’t seen anyone talking about this exact scenario. I’ve probably just missed it. Maybe someone can point me in the right direction. If not, any advice on how to make this work?

#2

Interesting observation… So it sounds like the physics (hardware) would make this a possibility, but I’m betting the firmware doesn’t.

I don’t have the answer, but if there is a firmware configuration option to enable the functionality you describe, it sounds useful enough that it would be documented. Have you poured through the specifications manuals?

The only remaining possibility is hacking the firmware, but I seriously doubt that anyone bothers trying. This isn’t a smartphone (etc.) for which hacking brings uncountable benefits.

#3

The switch is drawing its own power from the neutral while the fixture is being powered from the load, so it’s not the same.

And each device has only one device type handler active on the network. It can’t have two at the same time, it’s just not how zwave works.

That said, you should still be able to get the same end result you want easily – – just wire the current to the bulb so that it bypasses the micro all together and then have the switch toggle the micro, the micro talk to the hub, and the hub talk to the bulb wirelessly. People do this with regular zwave switches, you should also be able to do it with a micro.

In fact, the most common way of doing this is to install a non-loadbearing Z wave switch like the gocontrol auxiliary. It makes the wiring really easy because the switches are not designed to have the load anyway. But it’s the same idea. When you press the switch, the current to the Bulb doesn’t change. Instead, the switch sends a message to the hub and the hub sends a message to the bulb.

These options are covered in the following FAQ:

1 Like
#4

Fair point about neutral vs load, but it doesn’t change the fact that each can be powered independently. All of that is moot based on your second point.

@tgauchat The fact that zwave can only have one device type handler per device rules out a firmware config option.

I’ve read the FAQ you’ve linked to in the past. While I know the bypass option gives me essentially the same result, something about it just didn’t sit right with me. Doing it on the software side felt less permanent, easier to troubleshoot and (probably irrationally) less safe. It seems to be my best option though.

Thanks for the advice!

3 Likes
© 2020 SmartThings, Inc. All Rights Reserved.