Thanks for the reply. I did go through your project, but couldn't really find anything related to controlling and monitoring the current status of the light in existing 2-way switch circuits. Please provide me a link or additional info, if I did miss on something.
I am sorry. I have not read the forum for some days and I was not able to answer.
Anyway, I can explain the concept of the schematic and its aim. The basic concept is to make a "3 relays circuit". First relay to change between manual and remote mode, second one to let pass the current from the fase cable, and the third one works as "inversal" relay, detecting the change of state of the switch connected to the fase cable.
Why to use this concept? Ok. For me it was essential two things:
1- manual mode has preference over remote mode, so if the state of the switch is changed, by internal programming at Arduino board, the remote mode is always disconnected (this can be changed for emergency modes, as it is controlled by Arduino)
2- If the PCB has a problem and it does not work, all the PCBs are a cable. The current will arrive directly from the fase cable that it pass through the switch. It always work in manual mode. Without current at relays the only way to work is manual mode.
I hope that I have been able to answer the concept of my circuit.