Evaluation units with fieldbus interface are specialized industrial devices designed for testing and monitoring fieldbus communication systems. These units are typically produced by leading automation and control companies, such as Siemens (Germany), Schneider Electric (France), and Rockwell Automation (USA). They serve industries like manufacturing, process automation, and energy management by ensuring reliable data exchange between sensors, actuators, and control systems. Key products include interface modules, diagnostic tools, and protocol converters supporting standards like PROFIBUS, MODBUS, and CANopen. These evaluation units help engineers optimize network performance and troubleshoot connectivity issues in industrial automation setups.