Method for sensing input signal changes

摘要

A method for sensing input signal changes at an input of an input/output module operated in an automation system in which a signal is sampled by an input/output module. A change event and a timestamp associated with the change event are generated when a change in the sampled signal occurs and a value pair comprising the change event and the timestamp is stored in a higher-ranking automation component to the input/output module. The input/output module and the higher-ranking automation component are operated clock-synchronously with respect to one another by a clock pulse, and the timestamp is calculated centrally on the higher-ranking automation component based on the clock-synchronous operation.

主权项

1. A method for sensing input signal changes at an input of an input/output module operated in an automation system, comprising:
sampling a signal by the input/output module, generating a change event and generating a timestamp associated with the change event in a higher-ranking automation component having a higher ranking than the input/output module when a change in the signal occurs; storing a value pair comprising the change event and the timestamp in the higher-ranking automation component having the higher ranking than the input/output module; operating an edge detector in the input/output module to detect when the signal change occurs, and operating the higher-ranking automation component clock-synchronously with respect to one another by a clock pulse, the timestamp being calculated centrally on the higher-ranking automation component based on the clock-synchronous operation; and incrementing a counter in the input/output module for each value sampled; wherein the timestamp is generated by addition of an instantaneous time at a time instant of the clock pulse and a multiple of a sampling interval of the input/output module; wherein the signal is sampled in the input/output module at a frequency resulting from a division of a clock period of the clock pulse by the sampling interval; and wherein a count of the counter yields a multiple used for calculating the timestamp when an edge is detected by the edge detector and said multiple is transmitted to the higher-ranking automation component.