Rockwell Automation 1756-IH16ISOE ControlLogix Sequence of Events Module - Manual (Page 106)

Publication 1756-UM528A-EN-P - April 2004
7-20 Using The Sequence of Events Module in FIFO Mode
Clearing All Data From the
Module’s Buffers At Once If necessary, you can reset the events in the Sequence of Events
module’s on-board buffers, in effect clearing all data from
previously timestamped transitions. In other words, when all data is
cleared from the module’s buffers, all of the module’s input tags
return to 0, except data that is a live, filtered view of the inputs.
To reset events in the module’s buffer, transition the O.ResetEvents
tag to 1 as described below:
• If the bit = 0, change the bit to 1.
• If the bit = 1, change the bit to 0, wait for at least one RPI, and
change the bit to 1.
Once the data is cleared, the module begins timestamping input
transitions normally and storing them in its on-board buffer.
Changing Between
Retrieval Methods When using the Sequence of Events module in FIFO mode, you may
determine that you need to change retrieval methods. You can change
retrieval methods, but keep the following in mind before doing so:
• The change will NOT take effect until all events are
acknowledged/cleared from the module’s buffers.
• When you change retrieval methods dynamically, the ideal
way is to reset events in the module buffers (as described
above) and immediately switch FIFO retrieval modes. Make
sure you do not need the data being cleared from the module
buffer prior to resetting events.
To change retrieval methods, change the O.RetrieveByPoint tag to
the new method.
• To use the standard retrieval by time method,
O.RetrieveByPoint = 0
• To use the retrieval by point method, O.RetrieveByPoint = 1
Chapter Summary and
What’s Next In this chapter, you read about using the Sequence of Events
module’s features. Chapter 8 describes the Troubleshooting the
Sequence of Events Module.