Runnable simulator field guide
SET and RESET latched start-stop scenario: test checklist
Direct answer
The learner can predict latch state for start, stop, simultaneous command, repeated scan, reset and restart cases and explain the safe limitation.
Written for pLC beginners comparing seal-in logic with SET and RESET instructions and learning why output ownership and scan order matter.
Scenario setup
Start and stop inputs, state bit, set and reset instructions, rung order, output owner, stop priority, retention, first scan and feedback.
I/O and state map
Operator inputs through ordered set or reset execution to stored state, output request, modeled machine response and independent feedback.
Normal run
Start, held start, stop, second start and normal reset executed from a known false state.
Boundary run
Simultaneous start and stop, duplicate writer, skipped reset, power return, faulted feedback, mode switch and stuck input.
Injected fault
An input, instruction-order, stored-state, priority, output-owner, retention, feedback or expectation defect.
Target check
The pattern regression-tested with exact target set and reset semantics and a documented safe-state strategy.
How does SET and RESET start-stop logic work?
SET stores the run state after the start event and RESET clears it after the stop condition, with final priority determined by the target and execution order.
Should stop have priority over start?
For ordinary motor control, deliberate stop priority is a common requirement, but the actual machine risk design and safety functions govern.