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Rockwell Automation Publication ICSTT-RM446N-EN-P - April 2018
Chapter 5
Checklists
Override Requirements Checklist
Input/Output Module Configuration Checklist
Description
Yes/No
Are the effects of overriding fully understood, particularly where the override action will affect
independent parts of an application?
Has a method of enabling, or more importantly removing, the overrides for the system as whole, or
individual sub-systems, been provided?
Have programming or procedural measures been defined to ensure that no more than a single
override may be applied to a given safety-related process unit?
Have indication of the presence of override conditions and recording their application and removal
been defined?
Is there an alternative method of removing an override?
Are there programming or procedural measures to limit the period of override?
Description
Yes/No
For each of the I/O signal types, do the I/O module settings provide the correct characteristics and
behavior for the intended sensor or actuator?
Have the thresholds been verified with both increasing and decreasing field signal levels and with
margins to allow for the measurement accuracy?
Do threshold states remain unique under all operating tolerances?
For all configurations, have tests been defined and executed to 100% test the required operation?
Have Dual Output modules been configured for Energize to trip SIL 3 applications?
Has guidance been followed to ensure that SIL 3 signals are shut down outside the time limit
imposed by the MTTR assumed for the PFD calculations?
Has the "Hold Last State" been set up for the Digital Output channels and if so has the affect on the
safety functions been taken into account?
Has input or output forcing been used on any channels and has the affect on the safety function been
fully taken into account so that it does not jeopardize functional safety?
Has a method of manually removing a forced condition (e.g. manually operated switches) been set
up to remove the forced condition on safety related inputs?
Has the Workbench system configuration backup copy been tested?
