A method of operating an automation system cyclically communicating with a central unit in accordance with a send clock and a predetermined reduction ratio using a first cycle time, wherein the central unit uses a send clock SCC for its communication, and communicates with the automation device taking into account the send clock and a reduction ratio of the automation device, and wherein the send clock for the automation device is divided by the send clock of the central unit, the largest power-of-2 value smaller than the division result is selected and multiplied with the reduction ratio of the automation device resulting in a reduction ratio of the central unit for communicating with the automation device, and the reduction ratio of the automation device is used to step down the send clock of the central unit for cyclically communicating with the automation device using a second cycle time.