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.
Ladder Logic (LD)
Relay-style graphical PLC language.
IEC 61131-3 graphical language that mimics relay ladder schematics: rungs of contacts and coils evaluated left to right, top to bottom. Still the most widely understood PLC language among maintenance electricians.
See also: IEC 61131-3 · PLC
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.