PLC FAT and SAT checklist: test behavior and handover evidence
Plan factory and site acceptance around requirements, observable results, failure states, approved changes and recoverable project files.
Fail-safe
Failure behavior that brings a process to its defined safe state.
A design that moves equipment to a defined safer state when power, signal, communications, or a component fails. The safe state is process-dependent: de-energize-to-trip is common, but not universally correct.
See also: Functional safety · Safety relay · Safety instrumented function (SIF)
Use the concept: 4–20 mA loop scaling · Industrial automation fundamentals · Modbus RTU CRC & frame helper
In depth
PLC analog input scaling: raw counts, 4–20 mA and diagnostics
Map raw counts into engineering units, check the configured channel range, and keep signal-quality diagnostics separate from the displayed value.
OT backup and restore testing: prove the recovery path
Inventory the files and dependencies needed to recover a control system, set recovery objectives, and test restoration on an isolated target.