Rockwell Automation 1756-IH16ISOE ControlLogix Sequence of Events Module - Manual (Page 85)

Publication 1756-UM528A-EN-P - April 2004
Using The Sequence of Events Module in CST Per Point Mode 6-13
Figure 6.5 shows when to clear data from the Sequence of Events
module. In this example, the Sequence of Events module sent input
data to the controller, and the controller copied the relevant input data
to a separate structure. Now, the controller must clear the data from
the Sequence of Events module.
In this example, to clear data from the Sequence of Events module,
the controller writes the following to the Sequence of Events
output word:
• O.EventAck.2 = 1
• O.NewDataAck.2 = 1
Figure 6.5
If Latch CST is disabled, the controller does not need to clear
timestamp data. In this case, Sequence of Events module sends new
data, from subsequent transitions, to the controller as soon as they
occur. The controller overwrites timestamp data from the last
transition, regardless of whether it saved the data or not.
0 0 0 0 0 0 0
0 0 0 0 0 0 0
0 1 0 1 1 0 0
0 0 0 0 0 0 0
0 0 0 0 0 0 0
0 0 0 0 0 0 0
0 0 0 0 0 0 0
0 0 0 0 0 0 0
I.Fault
I.EventOverlow
I.ReturningUCTTime
I.EventNumber
I.Timestamp[16].OffOn[2]
I.Timestamp[16].OnOff[2]
I.Data
I.NewData
42793
1. Input 2 transitions
from OFF to ON.
2. Module timestamps
the transition.
3. Module sends
input data to
the controller.
Sequence of Events module ControlLogix controller
Controller tags
Separate array
5. Controller clears data from input 2 on the Sequence of Events module.
O.EventAck.2 = 1
O.NewDataAck.2 = 1
I.Fault
I.EventOverlow
I.ReturningUCTTime
I.EventNumber
I.Timestamp[16].OffOn[2]
I.Timestamp[16].OnOff[2]
I.Data
I.NewData
4. Controller
copies
relevant
data from
controller
tags to a
separate
array.