A quick update: Sections work now, using one pin per relay. Had to solder in a capacitor between ground and +5V to filter out some interferences (at least thats what Ive been told, no electronics expert) to make it work. Maybe something to consider if someone would redesign the relay driver pcb. Got the same problem as described earlier with no pulses from a polmac sensor, seems to work with a jumper instead of optocoupler. Is there another optocoupler model that might work with these sensors?