"How is the supply to your board arranged and what additional I/O do you have connected to it that is connected to external devices?"

The board is supplied with a wall transformer which supplies 12 V Dc. And the DC voltage is regulated with a 7805. All the I/O connection is done with optocouplers.

"a cheaper alternative would be to use a couple of optocouplers in combination with a galvanically separated miniature DC/DC converter to supply the driver (MAX232 or similar). "
What do you mean by galvanic separation? Is it possible to give some site addresses.

Thank you very much.
Ertan Balaban