I am trying to build up a home automation system(retrofit) with existing conventional switches(230VAC).

But I am looking for automation system without replacing existing conventional switches along with controller digital output. In this case I need to control from both possible outputs. i.e either of command should turn ON/OFF the lights.

This is how fibaro zwave relays operate. FYI... enter image description here

In simple terms, just connect this fibaro switch with existing switch then you can control the load from both existing switch and controller location.

Same way,please help me out to bring this to home automation PLC.

1 Answer 1


That wiring diagram looks fine.

The system was already designed with your requirements in mind. The relay controls the light but it also listens to the input from the old switch, which is on the bottom left in your diagram.

It appears the best place to put this module is in the ceiling rose, given that all the wires it needs are already there.

  • Thanks for your reply. I like to replicate this into PLC controlled system without modifying the existing wiring.
    – CAuto
    Sep 25, 2017 at 3:59

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