Abstract: There is disclosed a method of synchronising operation of at least one component of each of a plurality of serially connected devices (1000) connected to a common power source. The method involves sending cycles of serial interrupts (610-619) to each of the serially connected devices (1000), allocating an operation time slot (600,602,604,606,608) to each serially connected device (1006) corresponding to at least one interrupt of each cycle, each at least one allocated time slot being different, and controlling operation of at least one component (222) of each serially connected device to operate only during the time slot allocated to the serially connected device.