I got to talk with the person who installed the card, while he did not answer all my questions, he did tell me a few useful tips. The card is on an ISA bus in the PC and spawns 4 addresses (usually 300h,301h,302h,303h) The first 3 addresses are the digital inputs/outputs pins, so to send a message to an output, you send the adress and the proper byte (0-7). Anyone has a clue on how to send messages to an physical address on a pc ? Thanks, Nat