Rockwell Automation 1756-IH16ISOE ControlLogix Sequence of Events Module - Manual (Page 11)

1 Publication 1756-UM528A-EN-P - April 2004
Chapter
1
What is the ControlLogix Sequence of
Events Module?
What This Chapter Contains This chapter describes the ControlLogix Sequence of Events module.
What does Sequence of
Events Module Do? The ControlLogix Sequence of Events module is a DC input module
that offers sub-millisecond timestamping on a per point basis in
addition to providing the basic ON/OFF detection as found on other
ControlLogix input modules.
Timestamping is a ControlLogix feature that registers a time reference
to a change in input data. In ControlLogix, the time mechanism used
for timestamping is the Coordinated System Time (CST).
Timestamping Using the Coordinated System Time (CST)
The Coordinated System Time (CST) is a 64-bit, free-running timer
with microsecond (
µs) granularity on a ControlLogix backplane. A
time master (either a ControlLogix controller or 1756-SYNCH
module) generates the timer and sets it on the backplane. All other
modules in the chassis have access to the CST and adjust their time
reference based on the backplane time reference.
Table 1.1
For information on: See page:
What does Sequence of Events Module Do? 1-1
What Else Does the Sequence of Event Module Do? 1-3
Understanding the Module’s Physical Features 1-4
Using Module Identification and Status Information 1-5