Hello
I am looking for a smart relay coil. Basically I have a device that toggles a 24VDC output on/off based on certain conditions.
I would like to feedback the status of this output into HA over WIFI or Zigbee.
Does anyone know if such a device exists?
Can’t you just add a voltage divider and connect it to a pin directly or with an optocoupler to an ESP.
Thanks for the response, I could do that but really just looking for something off the shelf that will accomplish this. Surely there are voltage sensing relays that are MQTT or Zigbee compatible out there?
Or a shelly 1.
Thanks for the response. The first option is battery powered, not sure it would suit me.
The Shelly is an interesting device, however my output supplies 12V once on then 0V when off. I would need to detect this, but the Shelly seems to want to be always powered then to use that permanent power supply through a volt free switching contact. I’m not sure if it would work if the switching contact sourced power?
So if you don’t want a battery and don’t have a power supply I am not sure how you are going to manage it.
Although I have realised the Shelly 1 is probably not what you want 
You could use the shelly. It will be more expensive than DIY.
But since the shelly will only be powered when the input is on then it will be unavailable when the input is off.
That could be your way of knowing if the device is on or not.
But unavailable could be no wifi also.
I’ve found another system which has an open collector outputs that will change state once initiated (Ness d8x). It also has a 12V output supply on it. I think the Shelly 1 will do the trick with this.
The manual for the d8x states:
“The Aux1 to Aux4 outputs are open collector outputs (switch negative) which can supply a maximum of 100mA.”
So if I power the Shelly1 wifi switch via the 12V output supply, I am guessing the SW output will have a constant 12V on it and will be looking for a conductive path to ground in order to indicate that it has operated?
Does this mean when AUX1 changes to TRUE state, it will conduct to ground and current will flow from the SW terminal and back to the L terminal via the D8x controller?
Also, can you change configure the Shelly 1 to close the dry contact terminals only when it has received a command via MQTT? (i.e. don’t automatically close if SW is initiated).
This way I can arm/disarm the system via Z8/C (which should be internally limited) from my server.
And can the Shelly 1 provide status of SW via MQTT?
My proposed schematic is attached:
You may have a solution already but if not, you can use a 24v relay connected to a gpio binary switch in esphome. The relay will close a set of dry contacts when 24v is supplied.
