Disclosed herein are embodiments of a method for controlling a slave device in a system including a master device and a plurality of groups of slave devices. In one embodiment, the method includes generating, by the master device, a control message containing group data items each corresponding to the respective groups to transmit the control message to a particular group; transmitting, by a slave device included in the particular group, the control message to a next group; extracting, by the slave device, a group data item from the control message after the transmitting the control message; extracting/writing, by the slave device, data from/onto the group data; and transmitting, by the slave device, the group data to the master device after completing the extracting/writing.