INTERFACE CIRCUIT

PURPOSE:To prevent an accident beforehand by checking an identification address before the connection of interface circuits and preventing connecting the interface circuit to be misset to a common bus. CONSTITUTION:Interface circuits 2b-2n are already connected to a common signal bus 1, and when an interface circuit 2a is newly connected, whether an identification address 3a inherent in the interface circuit 2a is already assigned to the other interface circuits 2b-2n and is used or not is discriminated. When it is already used, the interface circuit 2a to be newly connected is prevented from being connected to the common signal bus 1. Thus, a malfunction and a destruction cannot be caused.