Method of determining the actual power output of power supply units in an automation network

The method involves providing source modules (4-6) with load-distribution controller (3) that is attached to a bus (2). Rate of utilization of the source modules is represented based on voltage through the bus. Information about a power rating of the source modules and curves of the controller are provided in an evaluation unit (7). The curves and actual total-power output of the source modules are determined and displayed by the evaluation unit using power ratings voltage detected by the evaluation unit through the bus during the control operation. An independent claim is also included for an automation apparatus.