Sorry, i did not see your post before placing my last message.
I use a prebuild pcb with 4 relais ( cost 2,50 euro ).
I'm planning to make a pcb that would be a plugin board for this relais board.
From the tests i did it would be possible to create a module with 4 opto isolated inputs
and 4 relais outputs.
This would be a nice generic module for my purposes.
the link for a picture of the module is http://www.selloutsoon.com/albums/ebay/ ... G_0058.JPG
Gr, Data