The aim of this thesis is to describe an automatic machine for processing wooden chair legs. My work on this machine consisted of mounting and connecting all the input-output components to the main controller and developing a program in ladder logic. Firstly I describe how the machine and the controller work in general. Furthermore, I met with various issues from the safety viewpoint. Namely, I explain how the switch-off and functional safety requirements for the worker, the machine and the processed parts are met and realised. In addition, I explain the description of the program logic, which is divided into more subprograms based on their functions. Therefore the reader gets the full image of the machine and its operation.
The thesis ends with an explanation of an attempt to program the controller to utilize two high-speed counter inputs to compare impulses of a shaft encoder. It discusses the way I solved the occuring irregularity. The results show the importance of pre-planning when using a shaft encoder in automation and comparing encoder purpose with solvability of the problem using simpler methods.