Direct association establishes a direct connection between two Z-Wave devices, where one serves as the trigger and the other as the recipient of that trigger. Essentially, one Z-Wave device transmits a message directly to another, bypassing the hub. These commands are typically straightforward and unconditional, such as "on/off" or "dim/brighten." Communication occurs unilaterally, without providing feedback to the initiating device. The controlling device solely issues commands to the associated devices in what's known as an "association group." Although a connection exists between the two devices, it operates exclusively in one direction, with the controlling device unaffected by the controlled one.

Please note, the official Home Assistant Z-Wave add-on does not have association support at the moment; in order to use Direct Association you need to install the Z-Wave JS UI add-on, which supports direct association.

If you have the Z-Wave JS UI add-on, you can manage the associations under each node. 

1. Click on the controlling device's row/tile. In the example below, the ZEN77 (DA test) will be the controlling device, triggering the ZEN04 (DA test2) on/off. You will click on the triggering/controlling device (ZEN77 in the example below): 

2. Click on the Groups tab and then click Add:

3. Program the association according to the desired function via the group association (on/off control, dimmer control, etc). You can find the group associations supported for each device in the device manual.

Then select the device you want to associate with this controller. Below you'll see the Target Node is DA test2, which is the ZEN04 name from step 1 above. Finish by selecting Add again at the bottom of the window

4. The association will appear in the groups list if successful, as shown below:

Please don't hesitate to reach out with any questions!