Rockwell Automation 1756-IH16ISOE ControlLogix Sequence of Events Module - Manual (Page 23)

Publication 1756-UM528A-EN-P - April 2004
How Does the Sequence of Events Module Operate in a ControlLogix System? 2-7
When Enable CST Capture is enabled for specific points and
transitions occur for those points, the Sequence of Events
module not only captures the CST at the transition occurrence
but also sends input data to the controller.
Because the RPI and Enable CST Capture functions are asynchronous
to the program scan, it is possible for an input to change state during
program scan execution. The point must be “buffered” to prevent this.
Copy the input data from your input tags to another structure and use
the data from there.
TIP
To minimize traffic and conserve bandwidth, we
recommend you use a larger RPI value if the
Enable CST Capture option is used and the module
is located in the same chassis as its owner.
IMPORTANT
All points on the Sequence of Events module have
Enable Capture CST enabled by default for both
ON to OFF and OFF to ON.
Additionally, you must specify an RPI regardless of
whether you use Enable Capture CST on any input
points. The default RPI at module creation in an
RSLogix 5000 project is 10ms.