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Chapter 10
Use the Sequence of Events Input and Scheduled Output Modules
66
The following occurs in the process of the managing data coming from the
Sequence of Events module in CIP Sync/PTP Per Point mode:
1. The controller retrieves current event data from the Sequence of Events
module in one of two retrieval methods.
2. The controller copies the relevant portions of the current event data to a
separate array.
3. At the user's discretion, controller clears current data from the Sequence
of Events module by copying the current event number (I.EventNumber)
to the O.EventAck tag, preparing the module send data from the next
current event.
This process is described in the rest of this section.
Retrieve Data in FIFO Mode
In FIFO Mode, the Sequence of Events module automatically sends the
controller the data from the first timestamped transition in its buffer. The
controller must retrieve the data for the remaining timestamped transitions in
the Sequence of Events module's buffers.
The controller can retrieve data in one of the following ways:
•
Standard Retrieval – By default, the module uses this retrieval method
which returns events in order of occurrence.
•
Retrieval by Point
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.
Retrieval by Point
Retrieval by Point is similar to Standard Retrieval by time except that with this
method, the controller only retrieves timestamp data for input transitions that
occurred on a specific point.
Rockwell Automation Publication 1732E-UM003D-EN-E - November 2021
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