NETWORK COMMUNICATION SYSTEM

PURPOSE:To improve the efficiency of expansion by transmitting the data of the last terminal unit to the intermediate and the first stations by a manner that the right-side switch of the intermediate unit is converted in the receiving status and left-side switch of the last unit is in transmitting status. CONSTITUTION:The system consists of the n-pieces of terminal units TE1, TE2,...TEn which are loop-connected. All the units less the first one TE1 are of identical constitution. the difference between the first unit TE1 and the rest is that the former does not have the left-side switch. Of the unit TE2, the left- side switch SWL2 is connected to the input-side coupling transistor T 1, and the right-side switch SWR2 is to the output-side coupling transistor T 0. Between these two transistors T 1 and T 0, a receiving circuit RV2, a reception processing circuit RC2, a transmission processing circuit SC2, and a driving circuit DR2 are connected. Accordingly, any dedicated transmission line is not necessary between the first and the last terminal units. Additionally, in case of expansion of the system, what is needed is only to connect another unit to the last one, and therefore the expansion work becomes of improved efficiency.