One advantage of the Zigbee smart home protocol that I didn’t mention in last summer’s comparison was Bindings. This is where you bind a function of one Zigbee device to another, allowing the first device to control the second device directly.
Zigbee, as you may be aware, is a mesh network protocol. That means that every Zigbee device will connect to every other Zigbee device in range. Now, every Zigbee network also has a Controller, which is a device that issues commands to the network. In my case, this is my Raspberry Pi running Home Assistant, with a Sonoff ZBDongle-E plugged into it.
The advantages of bindings
However, when you bind two devices together, they can issue commands directly, without needing to go via the Controller. This is useful, because it means that devices can still work, even if your Controller is offline.
For example, let’s say you have a Zigbee motion sensor in your bathroom. You can set up a binding so that, when the sensor detects motion, it’ll turn on the bathroom lights. Once the binding is saved, this will work regardless of whether your Zigbee controller is online.
The other key advantage of bindings is that they should be faster. We’re probably only talking micro-seconds here, but as commands can be sent directly from one device to another without a round-trip to the Controller, they should be a little more responsive.
If you’ve ever bought Ikea Trådfri bulbs, these usually come with a remote that has already had a binding set up. That way, the remote will work with the bulb out of the box without an Ikea Dirigera hub (or other Zigbee controller). But both can also be paired with a Zigbee controller if you have one.
Setting up Zigbee bindings
If you use an off-the-shelf Zigbee controller like the aforementioned Ikea Dirigera hub, or a Philips Hue Bridge, then you may be able to set up bindings using these. I don’t, so I can’t advise, but bindings can be set up using Zigbee2MQTT (which I use) and Zigbee Home Automation in Home Assistant (which I don’t).
In Zigbee2MQTT, you need to select your device, and then go to the ‘Bind’ tab. It’ll then expose a list of ‘endpoints’ that can be bound. In my experience, these are just numbers, so you may need to experiment to see what, for example, ‘endpoint 242’ controls. You can then bind this to the endpoint of any other Zigbee device to control it.
It’s worth noting some key points here:
- Not all Zigbee devices support bindings
- Those that do may only allow expose limited endpoints for binding, so you won’t be able to control all aspects using bindings.
For example, I have some Zigbee colour lights (which I used in my grouping example). I can bind them to another Zigbee device to turn them on or off, but not to change the colour. That still requires communication from the Zigbee controller.
Other protocols
If you have more than one Z-Wave device, then you can set up ‘Associations‘ between devices which work in a similar way to Bindings in Zigbee. Home Assistant users can set these up using the Z-Wave JS UI addon. I’m not aware that Matter offers anything similar.
