Rockwell Automation 1756-IH16ISOE ControlLogix Sequence of Events Module - Manual (Page 17)

1 Publication 1756-UM528A-EN-P - April 2004
Chapter
2
How Does the Sequence of Events Module
Operate in a ControlLogix System?
What This Chapter
Contains This chapter describes how the Sequence of Events module
operates in a ControlLogix system.
Differences Between
Sequence of Events Module
and Standard Digital I/O In many aspects, the Sequence of Events module behaves the same as
other ControlLogix digital input modules. However, the module offers
several significant differences from other ControlLogix digital input
modules, including those described in Table 2.2:
Table 2.1
For information on: See page:
Ownership 2-2
Using RSNetWorx and RSLogix 5000 2-2
Propagating a Signal From Field Device to Backplane 2-4
Sequence of Events Module in a Local Chassis 2-6
Sequence of Events Module in a Remote Chassis 2-8
Table 2.2
Difference: Description:
Additional data produced for
controller The Sequence of Events module produces significantly more data for its owner-controller than
standard ControlLogix digital input modules. While other input modules only produce ON/OFF and
fault status, the Sequence of Events module produces data such as ON/OFF and fault status,
timestamp data, indication of whether new data was produced for specific input points or if
transitions were not timestamped.
Only one owner-controller per module While multiple controllers can simultaneously own other digital input modules, the Sequence of
Events module only supports a single owner-controller.
Rack-optimized connections not
supported The Sequence of Events module does not support Rack-Optimized Connections from the
owner-controller.
Change of State (COS) functionality in
Enable CST Capture feature The module does support Enable CST Capture, a feature used to timestamp input transitions, that
is analogous to COS. For more information on Enable CST Capture, see page 2-6.
No listen-only connections Controllers cannot make listen-only connections to the Sequence of Events module. All
connections between the module and its owner-controller are direct connections.
Input filtering on a module-wide basis Other digital input modules offer input filtering on a per group basis. The Sequence of Events
module offers two input filter settings–one for OFF to ON transitions and one for ON to OFF
transitions–and is set on a module-wide basis.