I use a n/c relay across the two wires (powered by a little 5v psu)
If the power goes out the relay closes and so the Foxx reports ‘closed’
Then a little app sends a message and makes the house speak (yep speakers are on ups power )
I like it, it has a cable for antenna and I can extend it, I can use it inside my safe box, it has a tiny hole where I can pass the cable so it will get strong signal. Nice find.
Ecolink makes great door sensors that have terminals you can use to connect external devices like a pressure pad. I have several of them working flawlessly.
Yessir...the ecolink is essentially the zwave plus version of the GoControl sensor I used. When I first set this up using the method @Cobra outlined (without the relay), I ran into issues where the contact would show as closed as soon as it was plugged into the USB adapter...not enough resistance on the cable I was using. I ended up disconnecting from the reed switch and connecting directly to the terminals and it worked great for my use case. It even had a cutout for the cable already so the install is clean.
If I decide to do this again, I'll probably get the ecolink since it's zwave plus.
Here's the image of the internals for the GoControl with the terminals (pic provided by @Navat604)
Haven't tried it, but the Xiaomi Door/Window sensors also look like they're easy to add leads to. If you don't have connection issues with them or you have an Xbee, then you can't get much cheaper then that for a dry contact sensor!
Well i tried on the xiaomi and it works when i touch the wires to get open and close status. However i failed on the code or maybe xiaomi cannot work. Force open and force close do not seem to do anything. Was trying to use as a dry contact relay.
I don’t follow? These do work as input. That’s what I’m now using to indicate when someone pushes a regular doorbell button.
These are input devices only. There’s no relay to close. However, there is the new Xioami Aqara Double Relay. I’m using that too for activating the Arm and Disarm of a fob, bringing at least a little local control to my iSmartAlarm system via HE. However these are not dry contacts from the factory, so I’m closing two 12O volt relays, to give me true isolated dry contacts. Works very well and it was inexpensive.
What he is actually doing there is using the xiaomi device to tell the hub the position of the switch (i.e. on/off)
You can obviously do that with HE and make it appear as a switch.
BUT,, the device won't switch anything by itself.
It's only like a controller.
You could use this to control connected bulbs using rule machine or something similar.
Here's the setup I'm using for the dual relay. This won't be as inexpensive for everyone. I got the Omron relays for free with visa reward points, but it is inexpensive still. Just need to make sure it goes into a project box so you are safe from electrocution. The Aqara dual relay module contacts do have 120v AC between them and ground, even when the relay jumper is removed. I had the project box already, so my costs were kept down. My out of pocket was just the dual relay module.
No door/window contacts of any kind will act as a relay. They are just translating a physical closing of contacts (i.e. The magnetic reed switch in the Mijia door/window sensor) to digital on/off.
If you need to translate from digital to the physical, then you need a relay like the qubino or the Xiaomi Aqara I posted above. But just to emphasize again, the Xiaomi are NOT dry contacts, hence the reason two extra 120v coil relays are needed. I'm closing contacts for a fob that runs off a 3.3v cell (which I converted too, so it doesn't need to be powered by battery). If I were to connect that fob directly to the Xiaomi Aqara Dual Relay, there would be some fireworks and smoke!