Runnable simulator field guide
Beginner OR logic scenario: test checklist
Direct answer
The learner can predict all input combinations, implement one explicit final output owner and explain how independent requests share a controlled result.
Written for pLC beginners learning parallel ladder branches, Boolean OR, multiple start sources, stop priority and the difference between commands and feedback.
Scenario setup
Two input requests, their active states, shared permissives, stop priority, output ownership, feedback, reset and expected behavior for every truth-table row.
I/O and state map
Each input state through a parallel branch or Boolean expression to combined request, permissive, final output command, modeled response and feedback.
Normal run
Either valid request produces the output, neither request leaves it off and the shared stop or permissive retains declared priority.
Boundary run
Simultaneous requests, chattering input, stuck request, changing permissive, one-scan pulse, feedback loss and restart.
Injected fault
An input mapping, contact truth, branch, combined request, permissive, final writer, output, feedback or restart mismatch.
Target check
The behavior recreated in the intended PLC language and tested with target I/O and machine stop requirements.
What is OR logic in a PLC?
The result is true when at least one of the defined input conditions is true; ladder logic commonly represents this with parallel branches.
Can two start buttons be wired as OR logic?
They can form alternative requests, but stop priority, maintained state, output ownership, safety and machine feedback must be designed separately.