Abstract: The data communication volume between the logic department of the fully electronic computer interlocking system and the fully electronic target controller is large, and the requirements for communication security, reliability, and real-time are extremely high. Therefore, this paper proposed a design scheme for the communication unit of the fully electronic target controller based on the two by two out of two architecture. The paper elaborated on the design of communication units, software functions, as well as communication network topology design, communication protocol design, security measures, etc., validated the proposed scheme. The verification results indicate that the communication data between the communication unit and the logic unit is complete, the communication quality is stable, and meets the design requirements.