A novel method based on the Discrete Event Sys tem (DES) theory is proposed to solve the compatibility and interoperability issues among devices from different manufactures for the application of IEC60870-5-104 in distribution networks. In this paper, the DES method, which is described by a Finite State Machine (FSM), is employed to model the communication procedure based on the IEC60870-5-104. In the model, each object on the application layer is represented by the FSM. In each FSM, the communication drives the FSM from state to the other which is also called state transition. The event set i...