A method is described for communication between a charging station 101 and a robot 100, via a pair of power lines 109 coupled between a power supply 103 in the charging station 101 and a battery in the robot 100. In operation of an example, the power supply 103 is sequentially switched between a first voltage level and a second voltage level in accordance with a predetermined signal pattern. The voltage level on the power lines 109 in the robot is monitored and correlated with a specific command to be executed by the robot.
