Rockwell Automation 1756-IH16ISOE ControlLogix Sequence of Events Module - Manual (Page 103)

Publication 1756-UM528A-EN-P - April 2004
Using The Sequence of Events Module in FIFO Mode 7-17
Acknowledging Latched Timestamp Data
In FIFO mode, the Sequence of Events produces data for the
current event data at each RPI until the data is acknowledged and,
thus, cleared from the buffer.
To clear data for the current event, and begin producing data for
the next event in the Sequence of Events module’s on-board buffer
when using Standard Retrieval, you must copy the event number
from the current event (located in the I.EventNumber tag) to the
module’s EventAck tag (i.e., O.EventAck).
Figure 7.5 shows how to clear data for the current event from the
Sequence of Events module. In this example, the controller has copied
relevant input data from the controller tags to a separate data
structure. The controller may use a COP or MOV instruction to copy
the current event number to the Sequence of Events module’s
O.EventAck tag and clear the data from the module’s on-board buffer.
Figure 7.5
Once the current event data is cleared from the Sequence of Events
module’s buffer, the module begins producing data for the next
event in its buffer at each RPI because that event has become the
current event. At this point, the process returns to Producing Current
Event Data on page 7-14.
0 1 1 0 0 1 0
1 1 0 0 1 1 0
0 1 0 0 0 1 0
1 1 0 0 1 1 0
1 0 1 0 0 1 0
1 1 0 0 1 1 0
1 0 1 0 0 1 1
0 0 0 0 1 1 0
1 1 0 0 1 0 1
1 0 0 1 1 1 0
1 1 1 0 0 1 1
I.Fault
I.EventOverlow
I.EventNumber
I.CSTTimestamp[2]
I.UCTTimestamp[2]
I.EventPoint
I.Data
I.NewData
43812
2. Module produces
current event data.
Sequence of Events module ControlLogix controller
1. Module stores data
in on-board buffer.
Current event
I.EventData
I.ReturningUCTTime
I.EventsQueuedCount
I.Fault
I.EventOverlow
I.EventNumber
I.CSTTimestamp[2]
I.UCTTimestamp[2]
I.EventPoint
I.Data
I.NewData
I.EventData
I.ReturningUCTTime
I.EventsQueuedCount
Controller tags
Separate array
3. Controller
copies
relevant
data from
controller
tags to a
separate
array.
4. To clear the current event from the Sequence of Events module buffer, the controller
copies the current event number (I.EventNumber) to the O.EventAck tag.