Method of operating an automation system

A non-statutory non-volatile computer-readable medium storing a computer program with program code instructions executable by a computer, the program code instruction performing a method comprising:

• a) dividing a send clock for an automation device by a send clock of a central unit, a result of the division being a non-power-of-2 value;
• b) selecting a largest power-of-2 value smaller than the result of the division and multiplying the selected largest power-of-2 value with a reduction ratio of the automation device to obtain a reduction ratio of the central unit for communicating with the automation device;
• and
• c) utilizing the reduction ratio of the central unit to step down the send clock of the central unit for cyclically communicating with the automation device using a second cycle time;
• wherein the central unit supervises communications received from the automation device, performs an error action after not receiving a communication message from the automation device within a time span equal or longer than a watch dog factor of the central unit multiplied by the second cycle time;
• and wherein the watch dog factor is a smallest integer larger than a predefined watch dog factor of the automation device multiplied by a first cycle time and divided by the second cycle time.

A central unit of an automation system, a computer program being loaded on the central unit, the computer program having program code instructions executable by the central unit, the program code instruction performing a method comprising:

• a) dividing a send clock for an automation device by a send clock SCc of the central unit, a result of the division being a non-power-of-2 value;
• b) selecting a largest power-of-2 value smaller than the result of the division and multiplying a selected largest power-of-2 value with a reduction ratio of the automation device to obtain a reduction ratio of the central unit for communicating with the automation device;
• and
• c) utilizing the reduction ratio of the central unit to step down the send clock of the central unit for cyclically communicating with the automation device using a second cycle time;
• wherein the central unit supervises communications received from the automation device, performs an error action after not receiving a communication message from the automation device within a time span equal or longer than a watch dog factor of the central unit multiplied by the second cycle time;
• and wherein the watch dog factor is a smallest integer larger than a predefined watch dog factor of the automation device multiplied by a first cycle time and divided by the second cycle time.