A low-voltage islanded dc microgrid contains a number of renewable energy sources, local loads, and energy storage systems (ESS). To avoid the over-charging and over-discharging situations of ESS, a coordinated control strategy should be used in islanded dc microgrids. In this paper, a novel bus-signaling method (BSM) is proposed to achieve autonomous coordinated performance of system according to different state of charge conditions. Additionally, a secondary coordinated control is introduced to restore the voltage deviation produced by primary control level without decaying coordinated performance. The proposed control algorithm and controller implementation based on BSM are also presented. Finally, real-time simulation results show the feasibility of the proposed approach by presenting the operation of an islanded dc microgrid in different testing scenarios.