Job-readiness and assessment field guide
CCST 036 interlock verification practice: readiness checklist
Direct answer
The candidate can distinguish a permissive from an interlock and trip, identify the final output owner and produce repeatable evidence for normal, blocked, tripped and reset cases.
Written for controls-technician candidates preparing to explain and test an interlocked equipment command from initial state through fault recovery.
Role scope
Requirement, initial state, command, permissive, interlock, trip, latch, final output, feedback, alarm, reset and restart policy.
Skills map
Operator request through conditions and arbitration into one output command, interface state, equipment response and independent feedback.
Core exercise
All permissives healthy allowing a deliberate start while each named blocking condition independently prevents or removes the command as specified.
Stretch case
Simultaneous command and trip, feedback timeout, trip chatter, reset held, cause still active, multiple writers and controller restart.
Troubleshooting
A requirement, input, condition, state, final-writer, output, equipment, feedback, alarm or reset mismatch.
Portfolio evidence
The result recorded as a test case and then revalidated against exact site philosophy and target-platform behavior.
What is the difference between a PLC permissive and an interlock?
A permissive is commonly a condition required before or during operation; an interlock enforces a relationship that prevents an incompatible or hazardous action. Naming varies, so the behavioral contract matters.
Should Reset make equipment start automatically?
Normally, clearing a trip or latch should not itself create an unexpected start. The design should define cause removal, reset eligibility and the separate deliberate command required for restart.