Connecting wired windows sensors

A friend of mine has wired windows sensors allover in his house. The wires arrive all on one point next to his main entrance - currently not connected to anything. He is now looking for something where he can connect all cables to review the status of all windows. One possibility could be an alarm system like dsc and connect this via a binding with openhab.
But he does not need/want an alarm system. He only wants to display the status of the windows. So that he can see, when leaving the house, all windows are closed. Therefor of course he can use a tab, hue´s … I am currently using a Fiabro Wall-Plug.
Any idea what to use to connect the cables from 15-20 windows to grap their status?

You could use an Arduino to read the status and a WLAN Extension to publish them via MQTT or if you use a Raspberry Pi as openHAB-Server you could directly use its GPIO pins with the GPIO binding. :slight_smile:

Thanks for quick repsonse, but how can I connect 20 cables with 2 leads per cable. Tihs would mean he needs 40 connections…

Depends on the sensors.

If the sensors are simple switches you can connect them like this (link: Arduino/Tutorial) . So you only need 20 pins.

Otherwise if you really need 40 pins you can expand the Arduino with Port Expander Chips using the I²C Bus (link:Arduino/PortExpander)

I can highly recommend a pokeys 57E, this will manage upto 55 I/O’s through a modbus interface. I found the recommendation on here (@sipvoip), and know a few others use them too.

I use it for:

  • PIR sensors
  • Contact (door) sensors
    and plan to add
  • Water flow meters
  • Alarm interface (a form of contact sensor)


There’s a fair chance the ex-alarm window switches are not simple on/off, but what alarm folk call “FSL” - they exhibit one resistance when ‘open’ and another when ‘closed’. Simple short- or open-circuit are then fault/tamper indications. Check a pair of wires with an ohmmeter before purchasing anything.

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Thanks for this information!