Rockwell Automation 1756-IH16ISOE ControlLogix Sequence of Events Module - Manual (Page 22)

Publication 1756-UM528A-EN-P - April 2004
2-6 How Does the Sequence of Events Module Operate in a ControlLogix System?
Sequence of Events Module
in a Local Chassis When a Sequence of Events module resides in the local chassis (i.e.,
the same chassis as the owner-controller), the following two
configuration parameters affect how and when an input module
multicasts data:
• Requested Packet Interval (RPI)
• Enable CST Capture
Requested Packet Interval (RPI)
This interval specifies the rate at which a module multicasts its data to
the controller. The time ranges from 250
µs to 750ms and is sent to the
module with all other configuration parameters. When the specified
time frame elapses, the module multicasts data. This is also called a
cyclic update.
Because each operational mode (CST Per Point or FIFO) generates a
unique set of controller tags, the operational mode determines exactly
what data is sent to the controller at the RPI. For more information on
which tags are generated in each operational mode and, therefore,
what data is sent to the controller at each RPI, see Appendix D, Using
Module Tags.
Enable CST Capture
Enable CST Capture instructs the Sequence of Events module to
capture the CST whenever specific input points transition. You can
use this feature to instruct the module to capture the CST when the
inputs transition from:
• OFF to ON only
• ON to OFF only
or
• both OFF to ON and ON to OFF