Then the only solution that is avaialbe to us is to use the transitor. I will try this method soon, but still before I will try to see if there is a firmware solution(there isn't probably). BTW. In the TI protocol w/o Ack, there is no handshaking, so a byte sent away by a calc CAN be recieved by multiple calcs. --- Sami Khawam a9501901@unet.univie.ac.at http://unet.univie.ac.at/~a9501901