Rockwell Automation 1756-IH16ISOE ControlLogix Sequence of Events Module - Manual (Page 99)

Publication 1756-UM528A-EN-P - April 2004
Using The Sequence of Events Module in FIFO Mode 7-13
Standard Retrieval
In Standard Retrieval, the controller retrieves the data for each
event in the order in which the events occurred. This retrieval
method includes the following:
1. At each RPI, the Sequence of Events produces the current
event in its on-board buffer.
2. The controller copies relevant input data from the current
event to a separate data structure for later use.
3. The controller clears the current event from the Sequence of
Events module’s on-board buffer by acknowledging the data
via the module’s output word.
4. When the current event is cleared, the next event in the
module’s on-board buffer becomes the new current event. If no
other events are present, the event data will be 0.
5. The Sequence of Events module produces the new current
event as described in step 1.
This process continues as long as the Sequence of Events module
timestamps input transitions and the controller continues to retrieve
the data for each transition.