This is the E_DELAY function block type for delayed propagation of an event as defined in Annex A of IEC 61499-1.

As shown in the event_delay service sequence, the normal operation of an instance of this FB type is to issue an event at the EO output at a time DT after the occurrence of an event at the START input, following which the FB returns to a state of waiting for the next START event.

As shown in the delay_canceled service sequence, the occurrence of a STOP event at a time less than DT following a START event causes an immediate return to the state of waiting for the next START event, without issuing an EO event.

As shown in the no_multiple_delay service sequence, the occurrence of a second START event at a time less than DT following the previous START event has no effect.