Disclosed is a system for controlling a pump, such as a submersible pump intended for pumping water, including a pump and a separate electronic control unit connected to the pump by an electrical cable. The control unit is adapted to be detachably connected to the pump. The control unit is adapted to allow the pump's power supply to pass through the control unit. An electronic controller is arranged in the pump for controlling at least one of the pump's functions and/or monitoring at least one of the pump's operating conditions. The pump and the control unit are adapted to communicate with each other and transmitting signals, including necessary control and/or monitoring information/data, between each other.