How do you design and execute Factory Acceptance Testing (FAT) for integrated control systems?

FAT design: define scope (hardware, software, simulation requirements), develop test procedures (systematic coverage of all functions, acceptance criteria), prepare test environment (temporary I/O simulation, process simulation, network infrastructure). Execution: witness testing with customer, document results (pass/fail, deviations, punch list), test all operating modes and failure scenarios. Categories: hardware verification (I/O checks, communication), software functionality (logic, HMI, alarms, reports), performance (response times, load testing), and safety systems (fail-safe behavior, trip testing). Address findings before shipment. Maintain test documentation for SAT reference. Typical duration 1-4 weeks depending on complexity.