A method of operating a plurality of driving units for powering electronic units comprises interchanging a data frame including a bit sequence, between a master control unit and at least one of a plurality of driving units at slave nodes. A step of applying an ID field comprises indicating the driving unit address using a first bit sub-string comprising N bits, allowing the master control unit to identify whether data should be received or transmitted, or allowing each addressed driving unit to decode which action is required by the master control unit, using an R/T command bit, performing a length decoding step, for including information in the ID field regarding the type of instructions included in the data frame, using an F function bit, and assigning data bits to different electronic units or indicating in the length of the bit string in the data field, using a second bit sub-string.