Due to the increasing demands on layer quality and process stability in thermal spraying in industrial use, there is an increased need for devices to characterize and control the complex plasma spraying process. Various types of diagnostics, some of which are already commercially available, have meanwhile been developed for this purpose. In industrial applications, there is a need for methods that are as simple as they are effective for determining the properties of the sprayed particles, since their state before they hit the surface to be coated is decisive for the characteristics and quality of the coating and is also strongly influenced by the spraying parameters. This article provides an overview of the general diagnostic procedures and shows possibilities for developing suitable methods that allow automated process control during plasma spraying. Paper includes a German-language abstract.