User manual

70 Publication 1756-RM093F-EN-P - January 2010
Chapter 7 Monitor Status and Handle Faults
Use the Output Fault Latch and Reset Flowchart to determine which
rungs of application logic in Ladder Logic Example 3
on page 73 are
required.
Input Fault Latch and Reset Flow Chart
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 safety
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 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 safety state value when
input is faulted. (Example Rung 4)
Done
Yes
No