Is there a Smart Switch solution (Sonoff R4 for example) that can be used to send the wind signal from my KT322N to another R4 Smart Switch?
I would like to remotely control my ventilation system which is already connected and controlled from an R4.
Knowing why would help envision a plan.
That does not sound like a remote, unless you are trying to remote using the laser to control the fan.
I googled Sonoff and see those are WIFI controlled switches. There appears to be no trigger input (switch closure) to control the receiver. Something like this (Amazon)…
DEWENWILS Indoor Remote Control Outlet, Wireless Remote Light Switch, No Interference Remote Outlet Switch, No Wiring, 15A/1875W, 100ft RF Range, Compact Design, Programmable
…can be adapted and sounds like what you might need.
Of course, I am guessing without more detail.
Yes, that was a bit loosely worded.
It is of course the Laser that is supposed to start and stop my ventilation system. Right now I control the exhaust manually by activating an R4 on the ventilation system
The R4 can also be activated over LAN directly or another eWeLink device can activate it via a “Scene”. Here is my thought that the output from the laser (KT322N) triggers an eWelink device which then triggers the ventilation itself.
My problem is the on/off signal from “wind”. How do I “convert” it to the respective Sonoff/eWelink device so that the signal can be used.
Typically there is an input 12-30 V DC and or 110-230 V AC and an output up to 230 V 10A. I will not use the physical output itself but through a Scene it should just activate/deactivate the R4 that is on the exhaust.
I don’t know if this explanation is better than the first 
I have not played with those toys, but you need a switch closure on the pin of the controller. I know nothing about the Ruida, so you need help from another on how to control the output. I expect the pin is TTL 5v, so a relay board can provide the switch action.
Amazon:
HiLetgo 2pcs 5V One Channel Relay Module Relay Switch with OPTO Isolation High Low Level Trigger
The eWeLink is also a WiFi app controlled device, and may not adapt to a switch closure input.
The RF receiver in my garage door opener croaked. I simulated closing the wall button with one of these remote relay units. You can easily wire across the A or B button and use the relay module to switch the fan. The module has clickon/clickoff capability, but I just used the momentary mode.
Amazon:
DieseRC Wireless Remote Control Switch 433Mhz 5V 12V 24V 1 Channel Radio Control Relay Receiver with 1 Transmitter Keyfobs Potential-Free Contacts Relay Controller
Based on a casual search, I think the S1/S2 terminals on a Mini-D are “dry contact” inputs:
Presumably the switch closure would send a message somewhere.
If so, then use the controller’s Wind output to close a relay connected to those terminals. A solid-state relay might work; if not, then one of these:
https://www.amazon.com/HiLetgo-Channel-Module-Isolation-Support/dp/B00LW2H5GC/
Which would need a connection to the 24 V supply, but that’s nearby on the controller.
I don’t have any automation configured to link my exhaust fan configured to my Ruida controller’s outputs, but if I wanted to implement something, I believe I’d likely go with a Shelly Uni. I already have all my lighting and ventilation in Home Assistant (with a custom dashboard on a wall-mounted tablet in my shop), so adding a Shelly Uni to read the outputs and writing a quick automation would be trivial.
(Of course, if I went that far, I’d end up with a good handful more so I could read the power and laser-on status of my other lasers and feed an alert light stack outside the door, and since I’m the only one who goes in my shop, that would be in the fun-for-fun’s-sake column.)
Thanks to everyone for your input.
But it’s getting too complicated for me. If no one has a similar solution already, I’ll probably use a hardwired solution with a standard relay.
I’ve seen this (standard) solution mentioned or used by several people here in the forum…
…Or, continued to use my index finger, which has done it well for the last 4 years 
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