Method for operating a programme-controlled highly available automation system designed redundantly with a first automation device (A) and a second automation device (B), for a technical process, wherein one of the two automation devices (A, B) preferentially controls the technical process via peripheral units (PE1, PE2, PE3) and the two automation devices (A, B) mutually monitor for failure of the respective other automation device (B, A), wherein a monitoring query (WD) from the first automation device (A) to the second automation device (B) and vice versa has to be responded to within a monitoring time (TO), for a communication the automation devices (A, B)and the peripheral units (PE1, PE2, PE3) are connected with one another via a ring (R), the automation devices (A, B) each have a first ring port (A1, B1) and a second ring port (A2, B2) in order to form the ring (R), wherein one of the ring ports (A1, B1; A2, B2) is operated as blocked so that circulating telegrams are prevented in the ring (R), the automation devices (A, B) and the peripheral units (PE1, PE2, PE3) additionally have routing tables (RT), wherein a measuring programme (M A , M B ) which is operated at least in one of the two automation devices (A, B), - wherein a desired ring interruption by blocking a ring port (A1, B1; A2, B2) is carried out by means of the measuring programme (M A , M B ) in order thus to provoke a ring reconfiguration which utilises a reconfiguration time (T conf ), - wherein the blockage of the ring port (A1, B1; A2, B2) blocked by the measuring programme (M A , M B ) is cancelled again after the reconfiguration time (T conf ) has elapsed by means of the measuring programme (M A , M B ), - whereupon the ring port (A1, B1; A2, B2), which has previously been operated blocked so that circulating telegrams in the ring (R) are prevented, is blocked again if it has been opened by the ring reconfiguration and all routing tables (RT) are deleted, as a result of which at least the peripheral units (PE1, PE2, PE3) are triggered to learn new network routes, the method is characterised in that - runtimes of test telegrams (TT) are measured and a maximum value (T lzmax ) of the measured runtimes is stored by means of the measuring programmes (M A , M B ), - the measured maximum value is now used for a dynamic adjustment of the monitoring time (TO). - wherein a desired ring interruption by blocking a ring port (A1, B1; A2, B2) is carried out by means of the measuring programme (M A , M B ) in order thus to provoke a ring reconfiguration which utilises a reconfiguration time (T conf ), - wherein the blockage of the ring port (A1, B1; A2, B2) blocked by the measuring programme (M A , M B ) is cancelled again after the reconfiguration time (T conf ) has elapsed by means of the measuring programme (M A , M B ), - whereupon the ring port (A1, B1; A2, B2), which has previously been operated blocked so that circulating telegrams in the ring (R) are prevented, is blocked again if it has been opened by the ring reconfiguration and all routing tables (RT) are deleted, as a result of which at least the peripheral units (PE1, PE2, PE3) are triggered to learn new network routes, the method is characterised in that - runtimes of test telegrams (TT) are measured and a maximum value (T lzmax ) of the measured runtimes is stored by means of the measuring programmes (M A , M B ), - the measured maximum value is now used for a dynamic adjustment of the monitoring time (TO). <EOS>