The production effectiveness of technical means is as well a result of technical solutions, which secure the needed reliability and good product quality during satisfactory time interval, as also a result of the project and realisation of the control system of the wear and tear process of elements and of the processing correctness of these technical means. The J. Dietrych formalization of system is used as a tool to analyse of two viewpoints: user's and operator's viewpoint, and manufacturer's and serviceman's viewpoint. As a result of the analysis the definition of the 'fitness' of technical mean' is given with the help of measurable criteria and using the mathematical formalization. Such a shape is very useful as a tool to design (especially by the help of computer) of diagnostic systems of operating and processing of each technical mean, not only production machines or lines. An example of application of the theoretical appartus is given in the case of BEFAMA carding set.