Runnable simulator field guide
Product-labeler PLC scenario: test checklist
Direct answer
The learner can associate one product with one label request, apply within a bounded window, detect missing or duplicate labels and route a failed item to a recoverable state.
Written for packaging learners programming a conveyor labeler with product sensing, label-ready status, applicator timing and downstream verification.
Scenario setup
Product identity, leading and trailing edges, conveyor speed, label-ready permissive, print request, application window, verification, reject and reset policy.
I/O and state map
Product sensor through tracked item state, print command, applicator output, label-present feedback, inspection result and reject confirmation.
Normal run
Each accepted product receives exactly one verified label while an unready labeler blocks or rejects according to the declared policy.
Boundary run
Closely spaced products, sensor bounce, label roll empty, late ready, missed application, duplicate trigger, inspection failure, restart and retained product state.
Injected fault
A product-tracking, readiness, command, applicator, verification, reject, timing or restart mismatch.
Target check
The sequence recreated with target motion, printer, inspection, guarding and line-clearance tests.
How should a PLC track products through a labeler?
Create one product state at a defined sensor edge, advance it by measured motion or bounded timing and close the state only after application and independent inspection evidence.
What should happen when the labeler is not ready?
Use an explicit policy to inhibit infeed, stop at a safe boundary or reject the affected product; do not silently lose the label request.