
Rockwell Automation Publication 1756-RM001I-EN-P - May 2012
25
Chapter
2
Features of the ControlLogix SIL 2 System
The diagnostic methods and techniques used in the ControlLogix platform let
you configure and program ControlLogix controllers to perform checks on the
total system, including configuration, wiring, and performance, as well as
monitoring input sensors and output devices. Timestamping of I/O and
diagnostic data also aid in diagnostics.
If an anomaly (other than automatic shutdown) is detected, the system can be
programmed to initiate user-defined fault handling routines. Output modules
can turn OFF selected outputs in the event of a failure. Diagnostic I/O modules
self-test to make sure that field wiring is functioning. Output modules use pulse
testing to make sure output switching devices are not shorted.
Module Fault Reporting
Every module in the system is ‘owned’ by one controller. Multiple controllers can
share data, in addition to consuming data from non-owned modules. When a
controller ‘owns’ an I/O module, that controller stores the module’s
configuration data, defined by the user; this data dictates how the module
behaves in the system. Inherent in this configuration and ownership is the
establishment of a ‘heartbeat’ between the controller and module, known as the
requested packet interval (RPI).
The RPI defines a time interval in which the controller and I/O module must
communicate with each other. If, for any reason, communication cannot be
established or maintained (that is, the I/O module has failed, the communication
path is unavailable, and so forth), the system can be programmed to run
specialized routines, which can determine whether the system should continue
functioning or whether the fault condition warrants a shutdown of the
application. For example, the system can be programmed to retrieve the fault
code of the failed module and make a determination, based on the type of fault,
as to whether to continue operating.
Topic
Page
Summary of Contents for 1756-L6 Series
Page 24: ...24 Rockwell Automation Publication 1756 RM001I EN P May 2012 Chapter 1 SIL Policy Notes ...
Page 76: ...76 Rockwell Automation Publication 1756 RM001I EN P May 2012 Chapter 6 FLEX I O Modules Notes ...
Page 126: ...126 Rockwell Automation Publication 1756 RM001I EN P May 2012 Appendix D Checklists Notes ...
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