The AY23 is a Mitsubishi bidirectional thyristor output module with 32 output points, rated AC100–240V, with 3mA leakage current when OFF, 0.5Hz+1ms response time, 8 points per common terminal, 38-point terminal block, short-circuit protection, and surge absorber. It uses a cyclic scan process: input sampling, program execution, and output refresh are all performed in a centralized manner. Input states are only read at the start of each scan; changes during execution are ignored until the next scan. Output refresh occurs at the end of the scan. The scan cycle length depends on CPU speed, instruction execution time, and instruction count. This centralized sampling and output method causes input/output response delays. For PLC selection, performance-to-price ratio should be optimized based on control requirements. The system program memory is read-only, factory-set, non-volatile, and stores management, monitoring, and compiler programs.