MULTIPLEX SYSTEM

PURPOSE:To reduce the influence of high frequency noise by connecting a main body equipment and plural slave equipments by using a coaxial cable, and providing a switch for transmitting signal switching and a switch for ground connection at the central conductor of these equipments concerning the multiplex system constituting an IC test device. CONSTITUTION:An IC tester main body, namely, a cabinet 1 and test heads 21 and 22 are connected by using coaxial cables 31 and 32 and on the cabinet side, the output terminal of a signal source 11 is connected through switches SW1 and SW3 to the central conductors of the cables 31 and 32. Then, a ground terminal GA of the signal source 11 is connected to the external conductor of this cable and on the other hand, the central conductors of the cables are connected to amplifiers A1 and A2 with loads RL1 and RL2 as input resistors on the side of the heads 21 and 22. The external conductor is grounded through SW2 and SW4. Thus, when transmitting a signal from the signal source 11 to the head 21, the SW1 and SW2 are turned on and the SW3 and SW4 are turned off and when transmitting the signal to the head 22, the ON/OFF of switches is inverted.