Abstract : When multiple brands of frequency converters are used together on the same paper machine production line, a programmable logic controller (PLC) can be used to realize communication control between the communication device and the various brands of frequency converters. This paper introduces the principle and implementation method of communication control to achieve stable operation of the paper machine. Keywords: Multi-brand frequency converter; paper machine; electrical control In the renovation of small and medium-sized paper machines, factories will replace some older frequency converters or those that are no longer usable due to frequent malfunctions with advanced frequency converters. This results in multiple brands of frequency converters or frequency converters of the same brand from different periods being used on the same paper machine. This phenomenon leads to differences in control between products. Therefore, coordinating the control relationship between them is the key to the electrical control of the paper machine. A coated white paperboard production line in a Zhejiang factory has a speed of 80 m/min and 19 drive points. Originally, it used ABB's ACS500 frequency converters. However, the frequency converters for the large cylinder 1 (15kW) and gloss cylinder (18.5kW) drive points malfunctioned and could no longer be used. The frequency converters for the main pressure (37kW) and calendering (18.5kW) drive points frequently alarmed during production, affecting production. Simultaneously, the factory wanted to add a sizing frequency converter control (belonging to DCS control). To save on modification costs, the factory requested the reuse of two still-functioning 22kW Siemens MM440 frequency converters from another production line. For the remaining two drive points and the sizing point, the factory requested the use of ABB's ACS800 frequency converters. Analysis showed that two Siemens MM440 frequency converters replaced the large cylinder and gloss cylinder drive points, and ACS800 frequency converters replaced the main pressure and calendering drive points. 1. Control System Composition The control system adopts open-loop control, and its block diagram is shown in Figure 1. The main equipment includes: Siemens S7.200 programmable logic controllers (PLCs), Siemens MM440 frequency converters, ABB ACS500 and ACS800 frequency converters, and an operator console. The PLCs and various brand frequency converters are combined to form an RS485 communication network to complete the electrical control of the paper machine. [b][align=center]For details, please click: Electrical Control of Paper Machines with Multiple Brand Frequency Converters[/align][/b]