The topic of this final paper is pellet boiler automation. In the introductory part of this paper, details about biomass are explained. The advantages, disadvantages and various applications of biomass and all its products, which are used more and more today as sources for obtaining various types of energy, are presented. Furthermore, the principle of operation of the pellet boiler is explained, and according to the list of requirements from chapter 6, automation will be carried out using the Siemens LOGO! Soft Comfort. The automation of the pellet boiler will be implemented using the FBD (Function block diagram) programming technique. Automatic operation of the system is carried out based on the input data read by the sensors and by sending a current signal to the PLC computer. Boiler switching on and off, supply of pellets, establishment of pilot flame, monitoring of working temperature and pressure parameters are automated. The specified operating parameters are monitored on the Logo device screen.