This is a peripheral device category for building FA control systems in conjunction with PLC main units. It includes programming software, program loaders, memory cassettes, communication cables, expansion units, battery units, power supply units, displays, operation panels, debugging tools, and more. These are complementary devices that enable function expansion, program development and maintenance, system monitoring, and operator operations that cannot be achieved with PLC units alone. Control panel wiring cables, connection connectors, and program transfer interface devices are also included. Distinguished from PLC main units and I/O modules, this category specializes in auxiliary equipment necessary for system construction and operation.