This paper presents a method to interconnect and synchronize two instances of real time simulation. A Bergeron transmission line model is utilized as interface between two simulation instances. Communication to transfer the necessary transmission line model quantities is implemented by utilizing TCP/IP socket communication. Part of the real time simulator includes the hardware communication facility. In regards to the necessary synchronization, an external precision clock source is used at the both ends of the communication. Each end would represent the separate instance of the real time simulation in synchronism. Again, part of the real time simulation hardware includes the necessary mechanism for the synchronization. The proposed concept is proved with a simple power simulation, separated into two instances of real time simulation, which are interconnected by communication and synchronized by external precision clock source.