Abstract: There is disclosed a network apparatus connecting BACnet/IP and BACnet/MSTP that are standard networks used in a building automatic control system such as equipments, electricity, lighting control of a building, more particularly, an apparatus for duplicating a router in a building automatic control system that can achieve stability of a network and reduce data transmission failure on a network and enable serial data transmission by controlling the other router to continuously perform a function of a router instead, when one of two routers installed thereof is stopped, and a controlling method thereof.

Abstract: The present disclose a method for controlling a building automatic control device comprising a CPU module including a main-CPU module and a sub-CPU module, a functional module and a host. The method comprises an initial operation step, a synchronization step, a conversion step, a restoring step and a reporting step. By the method, the CPU module which is duplicated to gain safety of a direction digital control (DDC) used in the building automatic control device operate continuously.