Matter Fan Component - Odd UI Behavior

[jvmahon]

The problem

I am seeing some odd behaviours on the Fan web UI.

The examples pasted below are for the VTM35-SN fan controller. The VTM35-SN is a 3-speed (low / medium / high) fan controller. I understand that one of these controllers was sent by Inovelli to Marcel so hopefully he can use that to reproduce and check this issue.

Background to the Issue

Normally, when adjusting the fan speed via the Low / Medium / High choices on the Web UI I see:

• Setting the Fan to "Low" (via HomeAssistant) results in a percent setting of 33%
• Setting the Fan to "Medium" (via HomeAssistant) results in a percent setting of 66%
• Setting the Fan to "High" (via HomeAssistant) results in a percent setting of 100%

So, based on that I'd assume the

"Low" setting is used for any percent from 1-33%
"Medium" is for percent in the range 34-66%
"High" is for percent in the range 67-100%.

All that makes sense.

The Issue

Note that the problem can be most easily observed if the fan control is paired to both iOS and HomeAssistant and for this explanation, I'll assume that it is.

The issue is that when I adjust percentages via another controller, Home Assistant does not properly show the fan speed.

Example 1

Assume the fan is Off" and I then adjust to about 12 % using iOS. what I expect is for the fan to turn on and see "Low" and "12%" in Home Assistant. However, as shown below, I do see the 12%, but the interface still shows "Off"

Note that if I check the "Matter Server" add-on and look at the endpoint attributes, I see that the FanMode = 1, and CurrentPercent = 12, so the device is reporting the attributes propertly and the Matter Server is decoding them properly, it just isn't conveyed correctly on the WebUI.

At 17%, the webUI will then show "Low" and it stays at low until about 50% where it will then switch to medium.

Example 2

As another example, notice in the image that the fan is now at 83%. This should be "High", but the webUI still shows "Medium". Note that the "High" cross-over doesn't happen until approximately 85%.

In these examples, the Matter Server does change the FanMode at the expected points (FanMode =0 for Off, FanMode = 1 if percent is 1-33, FanMode =2 if percent is 34-66, FanMode = 3 if percent is 67-100).

So, in the example below, the Matter Server shows FanMode = 3 even though the WebUI is behaving as if it was still "2".

End Comments

I have some familiarity with the Matter integration code and took a look - I can't see any reason it isn't working correctly, so this may be an issue with the underlying Fan web UI code which is beyond my understanding.

What version of Home Assistant Core has the issue?

2024.11.3

What was the last working version of Home Assistant Core?

No response

What type of installation are you running?

Home Assistant OS

Integration causing the issue

Matter

Link to integration documentation on our website

https://www.home-assistant.io/integrations/matter/

Diagnostics information

No response

Example YAML snippet

No response

Anything in the logs that might be useful for us?

No response

Additional information

No response

[home-assistant]

Hey there @home-assistant/matter, mind taking a look at this issue as it has been labeled with an integration (matter) you are listed as a code owner for? Thanks!

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