Abstract: The present invention relates to a control system performance tracking apparatus comprising: a data memory device coupled in use to a plurality of control devices of a control system, the data memory device being configured to: monitor the plurality of control devices; receiving data related to inputs, outputs and events of each control device; time stamp said data on a common time base; and store a resulting time-based sequence data for each of the plurality of control devices; and a processor configured to compile the sequence data for the plurality of control devices into a common data stack.