Ethernet-based field bus systems such as PROFINET not only form the backbone for modern automation solutions but also for future applications in the context of industrial IoT. Ethernet infrastructure in the shop floor has therefore high demands on availability and failure safety. Diagnostic access points should be installed in each network infrastructure; as mentioned in the PROFINET Planning Guideline. Thus, in case of failure, it is possible to react quickly and effectively to isolate and eliminate malfunctions. The netMIRROR diagnostic access point from Hilscher allows to passively observing frame traffic on the wire. Accidental transmission into the network and thus possibly unintended interference of the communication is physically excluded. The netMIRROR is thus also suitable as a secure and permanently install-able access to read-out data streams for industrial IoT applications.