An execution environment for executing an event-oriented control program of a programmable logic controller, wherein the control program comprises a plurality of functional modules to be successively executed, is configured to execute the functional modules in an event-controlled manner on the occurrence of activation events that are each associated with the individual functional modules. In this respect, the individual activation events of the functional modules to be successively executed form an event chain. The execution environment comprises a monitoring module for monitoring an execution duration of the functional modules of the event chain, wherein the monitoring module is configured to check the execution duration for an exceeding of a predefined time duration.