A method for controlling an automation system having control redundancy, wherein the automation system comprises at least a first controller, a second controller, and a plurality of field devices connected to the first controller and the second controller via a data bus, wherein the first controller and the second controller are configured to cyclically control an automation process of the automation system,
- wherein the first controller comprises:
- a first input-output unit for receiving input data from the field devices and sending out output data to the field devices,
- a first processing unit for executing at least one control task and for analyzing the received input data and for generating output data according to the control task, and
- a first output memory unit for storing the generated output data;
- wherein the second controller comprises:
- a second input-output unit for receiving input data from the field devices and sending out output data to the field devices,
- a second processing unit for executing the at least one control task and for analyzing the received input data and for generating output data according to the control task, and
- a second output memory unit for storing the generated output data;
- and
- wherein the method comprises:
- cyclically controlling the automation process of the automation system via the first controller in a first controlling step, wherein the first controlling step is executed in an n-th control cycle, wherein the n-th control cycle is executed temporally after executing n−1 control cycles, wherein n is a natural number≥2, and wherein the first controlling step comprises:
- receiving an n-th set of input data via the first input-output unit of the first controller in a first input receiving step;
- and
- sending out an (n−x)-th set of output data via the first input-output unit of the first controller to the field devices in a first output transmitting step, wherein x is a natural number≥1, wherein the transmitted (n−x)-th set of output data is generated based on an (n−x)-th set of input data received in an (n−x)-th control cycle according to the control task, and wherein the (n−x)-th control cycle is executed ahead in time of the n-th control cycle by x control cycles;
- transmitting the n-th set of input data from the first controller to the second controller in a first data transmitting step;
- processing the n-th set of input data and generating an n-th set of output data via the second processing unit of the second controller in a first processing step;
- storing the n-th set of output data in the second output memory unit of the second controller in a first output storing step;
- determining a malfunction of the first controller during an (n+x)-th control cycle in a malfunction determining step, wherein the (n+x)-th control cycle is executed later in time by x control cycles than the n-th control cycle;
- and
- sending out the n-th set of output data via the second input-output unit of the second controller to the plurality of field devices in the (n+x)-th control cycle for controlling the automation process in a further output transmitting step.