Job-readiness and assessment field guide
CCST practical 017 counter assessment: readiness checklist
Direct answer
The candidate can prove one count per intended event, test reset priority and diagnose missed or duplicate counts from scan evidence.
Written for controls candidates practicing a counter task with explicit event, accumulator, done-state and reset requirements.
Role scope
Count event, edge definition, accumulator, preset, done state, reset command, priority, retention, display and acceptance sequence.
Skills map
Physical or simulated part transition through input sampling, edge memory, counter instance, accumulator, comparison, output and operator indication.
Core exercise
A declared number of clean events increments once each, reaches done at the boundary and resets through the specified action.
Stretch case
Held input, bouncing input, simultaneous count and reset, preset equality, overflow, mode change, power cycle and retained accumulator.
Troubleshooting
A sensor, signal-conditioning, scan, edge, counter-instance, reset, comparison, display or retention mismatch.
Portfolio evidence
The pattern recreated and tested in the target controller with current instruction documentation.
Why does a PLC counter count only once while an input stays on?
Most count-up instructions respond to a false-to-true event, not every scan that remains true. Exact instance and prescan behavior must be checked for the platform.
What happens if count and reset are true together?
Priority depends on the program order and instruction semantics. Define the intended outcome and test the simultaneous boundary explicitly.