Abstract: For facilitating data communication between PLCs of different types in on-site distributed control system in cigarette industry, an energy saving control system for dust removal fan was designed on the basis of industrial Ethernet. The monitoring station server of host computer is used as a conversion station, and different PLCs are equally connected to the monitoring and controlling data acquisition system to realize the data communication between the PLCs via the industrial Ethernet. Three dust removal fans in the primary processing department in Nanning Cigarette Factory were tested in the energy-saving control system, normal production worked at energy-saving mode and during maintenance at bypass mode. The results showed that the two modes could be switched from one to the other reliably. Under the same working conditions, the electricity saving rate was above 40%, or 26 000 kW per year. This technology provides a support for the data exchange between PLCs under different protocols in industrial fields.