Abstract : This paper introduces the application of Siemens' new MM420 frequency converter on conveyor belts. This system uses the Siemens standard serial communication protocol (USS) to control the operation of the frequency converters. Keywords: Frequency converter; USS; Siemens standard serial protocol; BICO technology 1 System Overview Figure 1 shows the control flowchart of the bottle-making machine. After the bottles are manufactured, they are placed on a cooling platform and then arranged in a single row. This conveyor system contains four or five conveyor belts with different operating speeds. The fastest conveyor belt transports the bottles through ultrasonic testing and finally packaging. The distance signal between the bottles is detected and input to the PLC analog input. The conveyor belt speed is changed so that the bottles enter the ultrasonic testing device at constant time intervals. The speed change must be smooth to prevent bottles from falling over. Any damaged bottles will be transported back to the bottle-making machine for remanufacturing. This bottle-making machine has a total of 24 conveyor belts, each controlled by an MM420 frequency converter. All MM420 frequency converters are controlled by a PLC via the USS serial communication protocol. Because the MM420 has a built-in RS485 interface, it can be connected to a PLC host computer via this serial port. 2. System Configuration This system uses 5 x 250W MM420 frequency converters, 15 x 550W MM420 frequency converters, two x 1.1KW MM420 frequency converters, and two x 5.5KW MM420 frequency converters. Additionally, it includes 24 asynchronous motors and one SIMATIC S7 PLC. 3. User Benefits The use of frequency conversion speed control improves the production efficiency of the bottle-making machine, reduces the scrap rate, and decreases mechanical maintenance. Smooth starting of the frequency converter avoids load shocks and current fluctuations, preventing bottles from falling off the conveyor belt. A simple USS serial communication connection to the PLC allows for PLC control of the frequency converter's start/stop, setpoint input, and status monitoring of the frequency converter and motors. This reduces system wiring and saves engineering costs. The frequency converters can be installed side-by-side, saving installation space. [b][align=center]For details, please click: Application of Siemens MM420 Frequency Inverter in Bottle Manufacturing Conveyor Belts[/align][/b]