Many thanks for all the replies. I believe I got the gist of where to start and what to do. But also a few more questions.. For the monitoring of the relay contact I would suggest a circuit like this ( one for each relay each using a different gpio input ) this with the relays in the state shown wou...

Hi All, I am looking into setting up a RaspberryPi for monitoring our A/C redundancy box. The box has 4 outputs, 2 for each A/C unit. One is giving the status of operation and the other is for if the A/C is malfunctioning or not operating. The outputs are described as "dry contacts" (relays). In the...