Modern maintenance. PROFINET PROFINET enables the standardized communication of maintenance-relevant information in addition to the communication of conventional diagnostic events. PROFIBUS International defined a uniform device status model for this purpose, making it possible for devices with integrated status monitoring to communicate the need for maintenance resp. maintenance requests in standardized form and without programming overhead. This possibility is used, for example, for advanced reporting of increased attenuation on optical transmission paths (POF). Replacement of the affected POF cable can then be taken care of as part of the planned maintenance measures, avoiding unplanned downtimes. Example: material aging on FO cables. Selectively monitored. Glass fibers are used to set up optical network topographies for long distances, while plastic fibers made of light-conducting synthetic materials such as Polymer Optic Fiber (POF) or plastic-coated glass fibers such as Polymer Cladded Fiber (PCF) are used for short-distance optical network structures. The integrated system solution comprises passive and active network components and distributed field devices with integrated POF/PCF interfaces. During commissioning and operation, the cables are monitored for any attenuation caused by material aging.