Unfortunately, two dimmers won’t work together at one light, whatever dimmer type it would be. Thus, your plan will not work. You’ll have to replace the rotary dimmer with a simple two way switch to implement dimming with Shelly. Or - much better - replace the rotary dimmer AND the two way switch with push buttons. This allows user-friendly dimming with up and down buttons.
If you still want to use a rotary switch, you could also use a special 0-10V rotary switch and a Shelly 0-10V dimmer.
If you still want to use a rotary switch, you could also use a special 0-10V rotary switch and a Shelly 0-10V dimmer.
Are these devices (looking at the product images) aimed at controlling low-voltage 12v LED lighting? I've got 240V GU10 dimmable downlights already installed so maybe not compatible with this device?
Unfortunately, two dimmers won’t work together at one light, whatever dimmer type it would be. Thus, your plan will not work. You’ll have to replace the rotary dimmer with a simple two way switch to implement dimming with Shelly. Or - much better - replace the rotary dimmer AND the two way switch with push buttons. This allows user-friendly dimming with up and down buttons.
There is only 1 rotary dimmer involved, the other switch is a simple on/off in the 2-way setup.
Replacing one rotary dimmer with some push buttons on the wall face plate of 4 switches isn't ideal - creating more work and cost for a retro fit.
So just to clarify, the Dimmer2 SW input doesn't support variable rotary dimmer switches at all?
