Runnable simulator field guide
Vertical-lift conveyor PLC scenario: test checklist
Direct answer
The learner can prevent motion from an invalid state, prove destination and load transfer, detect overtravel or stalled motion and recover without uncontrolled descent.
Written for pLC learners sequencing a vertical transfer between levels with load, gate, position and motion feedback.
Scenario setup
Load presence and weight boundary, lower and upper positions, gates, brake or holding state, up and down commands, motor feedback, travel timeout and recovery.
I/O and state map
Transfer request through gate and load permissives, direction command, holding mechanism, motion, position feedback, unload proof and return state.
Normal run
One valid load travels to the selected level with mutually exclusive motion, bounded time and confirmed unload before the next request.
Boundary run
Empty request, overload, gate open, contradictory limits, stuck sensor, failed brake feedback, motor trip, overtravel, power loss and recovery.
Injected fault
A request, load, gate, position, interlock, command, holding, drive, timeout or feedback mismatch.
Target check
The sequence engineered and validated with exact lift mechanics, braking, protection and applicable safety requirements.
What interlocks does a vertical conveyor need?
Standard control should check load, access, position, direction, drive and holding conditions, while risk reduction and safety functions require a separate validated design.
How should a lift recover after power loss?
Establish physical load, position and holding state first, then require a deliberate approved recovery rather than assuming the last software state is still true.