Need help for selecting hardware..

[kapperi]

My problem is that I have 12 bistable relays and 16 buttons in my house. Relays work at 24v and buttons too.

At this moment buttons are directly connected to relays, and this works as a charm. But I really want to be able to control relays with Domoticz.

What is the best way to implemend 28 inputs and 12 outputs to domoticz? I was looking for ethernet i/o board but there is no possibility to have as much inputs. Industrial plc can be extendent to 28 inputs but how to control those from domoticz?

4 pcs of piface?

I can design my own piface like board with necessary input and outputs, but is anyone else intrested of din-rail mounted 8 in 8 out board with mcp23s17 chip so you can up to 8? Boards in row...

Hmm... Would it be better to make input and output boards separate?

Hardware can be done but programming cannot be done by me, thats why I was thinking to use same inputs and outputs than piface...