Classification of electronic components that connect electrical circuits in manufacturing equipment. Handles various connectors used for board-to-board connections in control panels, signal transmission with sensors and actuators, power supply lines, and communication cable relay. Specifically includes circular and rectangular connectors, D-sub/USB/RJ45 connectors, PCB pin headers and sockets, waterproof and heat-resistant industrial connectors, cable crimp terminals, and relay terminal blocks. Essential components for wiring connections in NC machine tool control systems, automation lines, and inspection equipment, clearly distinguished from switches.