Rockwell Automation 1794 FLEX I/O System with ControlLogix for SIL2 - Manual (Page 24)

Publication 1794-RM001G-EN-P - December 2011
3-2 FLEX I/O Modules
Using Digital
Input Modules General Considerations when using Any FLEX I/O Digital Input
Module
Regardless of the type of FLEX I/O input module used, there are a number of
general application considerations that users must follow when applying these
modules in a SIL2 application:
• Proof Tests - Periodically (for example, once every several years) a
System Validation test must be performed. Manually, or automatically,
test inputs to make sure that all inputs are operational and not stuck in
the ON or OFF state. Inputs must be cycled from ON to OFF or OFF
to ON. .
• Wire sensors to separate input points on two separate modules that are
on different ControlNet nodes.
• Configuration parameters (for example, RPI, filter values) must be
identical between the two modules.
• The same controller must own both modules.
• Monitor the ControlNet status bits for the associated module and
ensure that appropriate action is invoked via the application logic by
these status bits.