Reaction to faults, Using 1715 i/o modules in sil 2 applications, Input modules – Rockwell Automation 1715-OF8I Redundant I/O System User Manual User Manual
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Rockwell Automation Publication 1715-UM001C-EN-P - March 2014
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1715 Redundant I/O System in SIL 2 Safety Applications
Chapter 6
Reaction to Faults
The 1715-AENTR adapter reports faults via status indicators that turn red when
a fault is detected in the adapter. Fault indications are also sent to the user
application. These variables provide the following information:
• Module presence
• Module health and status
• Channel health and status
• An echo of the front panel indications
Using 1715 I/O Modules in
SIL 2 Applications
I/O modules can be replaced or installed online without affecting controller
operation provided at least one module is installed and is fully operational.
However, each module must be installed one at a time and allowed to start up
before the next module is installed.
Input Modules
The simplex and duplex termination assemblies are safety critical, that is, an input
or output attached to a field device, and provide termination for 16 channels.
They connect the field signals to the input modules. Both digital and analog
input termination assembly circuits have fuse protection.
Input modules support high availability when configured for duplex operation
and using the appropriate termination assembly.
Input modules can be configured to operate in SIL 2 energize-to-action or de-
energize-to-trip applications.
Reactions to Faults
If an input channel is not capable of reporting a voltage within a safety accuracy
specification of 1% of the full scale measurement range, then the module returns
safe values to the processor. Signals transition to a safe state if the module scan
time exceeds the connection reaction time limit (CRTL).
All I/O modules feature status indicators and can also report faults via
application variables. All modules provide the following status information:
• Module presence
• Module health and status
• Channel health and status
• Field faults
• An echo of the front panel indicators for each module
For additional information about status indicators, see
.