Start
Does this safety function require operator
intervention after a safety input failure?
Write logic to latch input failure.
(Example Rung 0)
Write logic to set inputs to safe state.
(Example Rungs 2 and 3)
Are the inputs used to drive
safety application instructions?
Can Circuit Reset be used for operator
intervention?
Is input fault information required for
diagnostic purposes?
Make sure that you select
Manual Reset for the safety
application instruction.
No
Yes
No
Yes
Write logic to latch input failure.
(Example Rung 0)
Write logic to unlatch input failure.
(Example Rung 1)
Are any inputs used in an
instruction with diverse inputs?
(DIN or THRS)
No
Yes
Yes
No
Write logic to set safe state value when an input has a
fault. (Example Rung 4)
Done
Yes
No