Looking for good limit switch + sonoff dry contact setup for garage

I’m looking to add a limit switch to my driveway gate.

The gate is a horizontal sliding gate. Using a sensor I want to check if it is open or close.
My idea is to use a SONOFF SNZB-04 which I have, connecting some wires and linking it to a limit sensor.

The basic use of the magnet does not work as there has to be a minimum distance between the 2 sensor parts (2cm) to allow the gate to slide.
And it seems this is too much for the out of the box working of the sensor. The same issue exists with all sensors that use magnets.

Does anyone has any experience with a good (affordable) limit sensor that can be connected to the Sonoff ?
Requirements would be :

  • water proof (IP65)
  • works with the Sonoff (3V)

I’ve found different sensors, but the mention other voltages so I’m not sure they will work.

Micro Limit Switch

I would prefer something with a spring, as this is easier to install.

Any advice would be welcome !



I presently use regular alarm system magnetic switches that are connected to Sonoff wifi MiniR2 modules that give me the fully opened/fully closed status of a trap.
I’m still locking for something more simple to also read opto switches.

Hi [rattatosk]

Did you get a solution to your dry contact sensor. I’m trying to setup something similar. I bough a Float Switch that works with a floating on top of a liquid which opens or closes the electrical circuit as the liquid level rises or falls. My idea was to use the ports S1 and S2 from the Sonoff Mini R4 to close the circuit and so I would be warned by Alexa the water level has gone down, however I’m affraid the S1 and S2 may not completly isolated and somehow I get 110V in the water tank.

Any success on your dry contact switch sensor?