Abstract: The invention relates to a control system (1) for light regulating devices such as blinds or shades. The control system comprises a control unit (6, 6') for connecting to a motor drive (7) of a light regulating device. The control unit comprises a first input (18) for receiving motor control data along a data supply line (9, 9"). A second input (17, 26, 26') is provided for receiving decentralized user commands for altering the position of the light regulating device. The control system is characterized in that the control unit (6, 6'), by means of an external command input (25') can be set into either a slave mode in which data can only be received or into a master mode in which data can be received and transmitted along the data supply line (9, 9'). Hereby any light regulating device can be selected as a master device for controlling the blinds in the same group. Preferably the command input of the control unit comprises a manually operatable switch such as a dip switch.