Job-readiness and assessment field guide
CCST 014 missing seal-in diagnosis: readiness checklist
Direct answer
The candidate can map the momentary start branch, maintained request, stop and overload conditions, final output and independent running proof, then identify why the state drops.
Written for controls candidates diagnosing a motor request that works only while the Start input is held.
Role scope
Start input, stop priority, permissives, maintained-state branch, auxiliary or memory feedback, final output and motor-running proof.
Skills map
Momentary command through branch logic, seal state, series stop conditions, final command, interface device, motor response and feedback.
Core exercise
One deliberate start maintaining after button release and one stop removing the request under repeated clean initial conditions.
Stretch case
Start and stop together, overload open, auxiliary missing, duplicated output, program scan order, power return and restart request.
Troubleshooting
An input, branch, maintained-state, permissive, final-writer, output-interface, motor or feedback mismatch.
Portfolio evidence
The corrected behavior retested for stop, overload, restart and target-platform scan semantics under approved procedures.
Why does a PLC motor stop when Start is released?
The maintained branch may be missing, addressed incorrectly, placed around the wrong condition, reset later in the scan or dependent on feedback that never arrives. Trace the final owner rather than only the visible rung.
Should seal-in logic use the output bit or an internal request?
Either pattern can be valid within a clear ownership contract. An internal request often separates sequence state from the physical output, but both require one deliberate reset path and independent feedback where needed.