Addressing and Diagnostic Units (ADUs) are specialized industrial components used primarily in automation and control systems. These units are produced by various manufacturers globally, including companies like Siemens (Germany), Rockwell Automation (USA), and Schneider Electric (France). ADUs serve critical roles in industries such as manufacturing, automotive, and process control by enabling precise addressing, monitoring, and troubleshooting of networked devices like PLCs, sensors, and actuators. Key products in this category include diagnostic modules, addressing interfaces, and communication gateways, which help optimize system performance and reduce downtime.