In this paper a networked monitor scheme with Powermonitor3000 monitor unit based on the DeviceNetfieldbus is proposed. We adopt SLC5/05 Controller produced by ROCKWELL Automation to controlPowermonitor3000 with DeviceNet fieldbus. Explicit Message mode, which is by M file communication mode, isutilized in this scheme for reading parameters, and this mode is the strongest DeviceNet communication mode. Thenetworked monitor scheme of Powermonitor3000 based on M file under DeviceNet is investigated. The procedure withPowermonitor3000 for online monitor electric transformer under DeviceNet fieldbus is introduced, which provides thereliable support for networked power distribution system and factory automation systems. The experimental results aregiven, in which the correctness and effectiveness of proposed scheme is verified.